chapter 5 management of grazing lands - usdachapter 5 management of grazing lands national range and...

United StatesDepartment ofAgriculture

NaturalResourcesConservationService

National Range and Pasture Handbook

Chapter 5 Management of Grazing

Lands

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5–1(190-VI, NRPH, rev. 1, December 2003)

Chapter 5 Management of Grazing Lands

This chapter primarily contains guidance for planning grazing managementon the various kinds of grazing lands. The chapter is divided into threemajor sections. Section 1, Managing Native Grazing Lands, gives guidanceon managing rangelands, grazed forest lands, and native and naturalizedpasture. Section 2 is Managing Forage Crops and Pasturelands. Section 3,Procedures and Worksheets for Planning Grazing Management, is proce-dures and worksheets for forage inventory, livestock inventory and foragebalance, determining forage composition and value ratings, stocking rateand forage value rating, and prescribed grazing schedule.

National Range and Pasture HandbookManagement of Grazing LandsChapter 5

5–2 (190-VI, NRPH, rev. 1, Decmeber 2003)

Chapter 5

5–3(190-VI, NRPH, rev. 1, December 2003)

Management of Grazing Lands National Range and Pasture HandbookChapter 5 Management of Grazing Lands

Contents: Section 1 Managing Native Grazing Lands 5.1–1

Section 2 Managing Forage Crop and Pasture Lands 5.2–1

Section 3 Procedures and Worksheets for Planning Grazing Management 5.3–1





Lands

Section 1 Managing Native Grazing Lands

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5.1–i(190-VI, NRPH, rev. 1, December 2003)

Chapter 5 Management of Grazing Lands


Contents: 600.0500 Managing rangelands 5.1–1

(a) Dynamics of ecological sites .................................................................... 5.1–1

(b) Establishing management objectives ...................................................... 5.1–2

(c) Determining treatment alternatives ......................................................... 5.1–2

(d) Planning grazing management ................................................................. 5.1–3

(e) Degree of grazing use as related to stocking rates ................................. 5.1–8

(f) Prescribed grazing schedule ..................................................................... 5.1–8

600.0501 Managing grazed forest lands 5.1–15

(a) Principles of forest grazing ..................................................................... 5.1–15

(b) Management of the overstory ................................................................. 5.1–15

(c) Management of the midstory .................................................................. 5.1–16

(d) Management of the understory .............................................................. 5.1–16

(e) Western native forest lands .................................................................... 5.1–19

(f) Inventorying grazed forest ...................................................................... 5.1–20

600.0502 Managing naturalized or native pasture 5.1–21

Table Table 5–1 Decision support for consideration of riparian areas 5.1–6

as key grazing area

Figures Figure 5–1 Relationship between grazing and root growth 5.1–4

Figure 5–2 Deferred rotation system model 5.1–9

Figure 5–3 Rest rotation system model 5.1–10

Figure 5–4 HILF grazing system model 5.1–12

Figure 5–5 Short duration grazing system model 5.1–13

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5.1–ii (190-VI, NRPH, rev. 1, December 2003)

Figure 5–6 Deferred rotation grazing scheme (April – October) 5.1–14

Figure 5–7 Canopy classes in a southeast forest site 5.1–15

Figure 5–8 Forage production clearcut for natural regeneration 5.1–16

with periodic thinning

Figure 5–9 Forage production clearcut or natural regeneration 5.1–16

with periodic thinning (compared to clearcut or

natural regeneration with no thinning)


with periodic thinning (effects of hardwood midstory)

Figure 5–11 Plant community response to grazing management 5.1–17


with periodic thinning (very high forage value rating

vs. low forage value rating)

Figure 5–13 Clearcut or natural regeneration using a 55-year 5.1–18

cutting cycle

Example Example 5–1 Plan for southern pine forest 5.1–18 *

5.1–1(190-VI, NRPH, September 1997)


The management of plant communities depends onan understanding of the ecological processes and theecology of the communities to managed. Some pro-cesses of change are so universal as to be consideredgeneral ecological principles. Others may be lesswidely applicable (regional) and more closely relatedto particular communities or individual characteristicsof a species.

600.0500 Managing range-lands

(a) Dynamics of ecological sites

The natural plant communities for an ecological siteare dynamic. They respond to changes in environment,to various uses, and to stresses by adjusting the kinds,proportions, and amounts of species in the plantcommunity. Climatic cycles, fire, insects, grazing, andphysical disturbances are factors that can cause plantcommunities to change. Some changes, such as thoseresulting from seasonal drought or short-term heavygrazing, are temporary; others may be long lasting.Changes may cross a threshold and cause a permanentchange in the ecological site potential.

Individual species or groups of species in a plantcommunity respond differently to the same use orstress, such as fire, changes in climate, and grazing orbrowsing pressure. It is normal for some plants to begrazed more closely and frequently than others whengrazed by livestock or wildlife. Most plants are sensi-tive to stress during some stage of growth. They maybe severely affected by improper use or stress duringcritical growth periods, but tolerant at other times.

Many plants respond to changes in the microenviron-ment in a unique manner that may be different fromtheir associated species. For example, some speciesare destroyed by fire, while the plant next to it thrivesfollowing a fire. The same weather conditions may befavorable for the growth of one species in a plantcommunity while unfavorable for another species inthe same community. A growing season in whichfrequent light rainfall occurs may be ideal for somespecies. Other species may depend upon deep soilmoisture, making frequent light rainfall ineffective forthat species even though the total rainfall may beabove average. Thus many complex factors contributeto changes in the composition, function, and trend ofplant communities. Not all changes are related tograzing by livestock. Many changes may be caused byclimatic fluctuations, fire, and extreme episodicevents.


5.1–2 (190-VI, NRPH, rev. 1, December 2003)

To develop alternatives with the decisionmaker formanagement of rangeland, NRCS employees mustunderstand how an ecological site or association ofsites responds to disturbance or other treatment. It isnecessary to identify the ecological site and under-stand the description for that site. The ecological sitedescription has the information necessary to interpretthe findings of inventories to determine the rating ofan ecological site.

(b) Establishing managementobjectives

Management objectives are developed and deter-mined with the landowner during the planning pro-cess. All inventory and other necessary informationfor the development of objectives and the applicationof the grazing management are gathered during theplanning process. The objectives of the landownerand those of the NRCS do not need to be the same,but they must be compatible. The management objec-tive must meet the needs of the landowner, theresources, and the grazing animals.

(c) Determining treatment alterna-tives

For most management units, there are several manage-ment alternatives. These alternatives must provide thekind of plant community that provides for and main-tains a healthy ecosystem, meets resource qualitycriteria in the local field office technical guide,produces adequate, available amounts of qualityforage for the grazing animals, and meets the needsof the grazing land enterprise(s) and the desires ofthe landowner. The plant community that meetsthese criteria is the desired plant community.

After the cooperator has set goals for the site basedupon the intended use, the NRCS conservationistprovides information and analysis to assist the coop-erator in selecting the appropriate plant community tomeet these goals. This plant community becomes thedesired plant community (DPC). The trend is deter-mined (see chapter 4), and the appropriate plans aremade by the cooperator to either maintain the existingplant community (if it is the DPC) or plan the appropri-ate transition from the present plant community tothe desired plant community. This decision sets the

stage for the selection of the appropriate conserva-tion practices and resource management systems forthe cooperator’s conservation plan.

The NRCS conservationist will use information fromthe ecological site description, trend determinations,similarity index determinations, rangeland healthdeterminations, and other information to assist theland manager. This assistance will provide alternativesthat would most likely lead toward the desired plantcommunity.

This stage of the conservation planning processinvolves the following steps:

• Inventory the present plant community anddetermine annual production for each species.

• Identify from the ecological site description thedesired plant community that meets the landmanager's goals and the resource needs.

• Determine what changes may be occurring(determine trend).

• Compute similarity index of present communityto the desired plant community.

• Determine how the ecological processes of thesite are functioning (rangeland health determi-nations).

• Determine what conservation practice alterna-tives and resulting resource management systemwill achieve or maintain the desired plantcommunity.

• Provide followup assistance to land manager inplan implementation.

• Provide assistance to monitor trend.

Conservation practices applied on grazing lands aregrouped into three categories to reflect their majorpurposes: vegetation management, facilitating, andaccelerating practices.

Vegetation management practices—Practices thatare directly concerned with the use and growth of thevegetation. Example are prescribed grazing andprescribed burning.

Facilitating practices—Practices that facilitate theapplication of the vegetation management practices.Examples are water development, stock trails, fenc-ing, and prescribed burning.

Accelerating practices—Practices that supplementvegetation management. These practices help to

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Management of Grazing Lands National Range and Pasture Handbook

achieve desired changes in the plant communitymore rapidly than is possible through prescribedgrazing management alone. In some instances, thepractices may be required to achieve desiredchange. Examples are brush management, rangeplanting, and prescribed burning.

This list of conservation practices is not complete.Definitions and standards for each conservation prac-tice are provided in the National Handbook of Conser-vation Practices. The local Field Office TechnicalGuide provides detailed information applicable to theconservation practices discussed, and others availableto be considered in development of alternatives withthe landowner.

(d) Planning grazing management

The Natural Resources Conservation Service providesassistance to cooperators who wish to apply grazingmanagement. The primary conservation practice usedis prescribed grazing. Prescribed grazing is thevegetation management practice that is applied to allland where grazing is a planned use. The grazing maybe from domestic livestock, semi-domestic animals(buffalo and reindeer), or wildlife. This practice hasbeen developed to incorporate all the methods andconcepts of grazing management. Prescribed grazingis the controlled harvest of vegetation with grazingor browsing animals, managed with the intent toachieve a specified objective.

The objectives developed with the landowner duringthe planning process determines the level of planningand detail necessary for the application of pre-scribed grazing. The minimum level of planning forthe prescribed grazing practice includes enoughinventory information for the landowner to know theproper amount of harvest to maintain enough coverto protect the soil and maintain or improve the qual-ity and quantity of desired vegetation. The availableforage and the number of grazing and browsinganimals must be in balance for effective manage-ment of grazing lands. This is done by developing afeed, forage, livestock balance sheet. This part of theinventory identifies the available forage from theland and the demand for forage by the livestock andwildlife. It identifies where and when shortages orsurpluses in forage exist. Procedures and worksheetsare in section 3 of this chapter (exhibits 5–1, 5–2,5–3, 5–4, 5–5, and 5–6).

Grazing is one of the major forces in defining whatplant species will dominate a site. Different grazingpressures by different grazing and browsing animalsfavor different plant species. If the grazing is severe,undesirable plants are generally favored.

Grazing management can be planned and applied thatfavors a particular plant community or species. Thiscan be done to meet the objectives of the landownerand the needs of the resource. Grazing managementhas been successfully planned and applied that hasfavored the re-establishment and increase in woodyplants along riparian areas while still providingquality forage for the grazing animal.

Alleviation of grazing pressures that have inducedcomposition changes in a community does not imme-diately and by itself terminate or reverse the changethat such pressures induced. Many plants, desirableand undesirable to grazing, are long lived. If increaseof undesirables is related to only the suppression ofthe desirable species, a change in grazing pressure andmanagement sometimes permits the desirable speciesto regain their competitive status and suppress theinvaders. Such a rapid recovery can occur only whenprior grazing has been harmful for a comparativelyshort time. Where plants have died, recovery de-pends upon establishment of new plants. Althoughplants of the original community are invigorated bythe reduction of grazing pressure and may suppressthe successor species, the seedlings of the originalspecies can become established in competition withthe undesirable species only under favorable condi-tions.

Defoliation of a plant by grazing reduces the photosyn-thetic capability of the plant. The leaves are the foodfactory. Rate of plant regrowth following grazing isdependent on the amount of leaf area remaining forphotosynthesis and the availability of active axillarybuds to initiate new tillers. Roots anchor the plants tothe soil, take up water and nutrients, and if healthy,enable the plant to survive stress from drought, cold,heat, and grazing. Root growth is dependent upon theenergy provided from photosynthesis. Figure 5–1illustrates the relationship between grazing and rootgrowth. Healthy plant roots are essential for soilstability and erosion control, especially in ripariansystems.



Management of the grazing animal is one of the mosteconomical methods to ensure the health and stabilityof the grazing land resource. For grazing managementto be successful, it must meet the needs of the land,

based on the NRCS Field Office Technical Guidequality criteria, the landowner, and the livestock.Meeting these needs is essential to the success of allgrazing management.

Figure 5–1 Relationship between grazing and root growth (Crider 1955)

No root growth for 17 days. 60 percent of root growth on 33rd day.

No root growth for 12 days. 96 percent of root growth on 33rd day.

Approximately 48 percent of root growth after 17 days.159 percent root growth on 33rd day.

Approximately 55 percent of root growth after 5 days. 192 percent root growth on 33rd day.

Averaged a 3 percent root growth stoppage for 14 days.223 percent root growth on 33rd day.

117 percent root growth on 3rd day. 250 percent rootgrowth on 33rd day.

129 percent root growth on 3rd day. 338 percent rootgrowth on 33rd day.

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Chapter 5



(1) Key grazing areas and key species

The grazing enclosure is the management unit forgrazing land. Every management unit has certaincharacteristics that influence the distribution of graz-ing. Among these characteristics are soil, topography,size of enclosure, location of water, fences, riparianareas, natural barriers, and the kinds and distributionof plants. In addition, weather conditions, insects,location of salt and minerals, type of grazing manage-ment being applied (frequency and severity of graz-ing), and habits of the grazing animals affect the pat-tern of grazing use. For these reasons it is impracticalto prescribe grazing use for every part of a large graz-ing unit or to prescribe identical use for all enclosuresof a farm or ranch. Determining the key grazingarea(s) in each enclosure and planning the grazing tomeet the needs of the plants in the key area are morepractical. If the key grazing area of a unit is properlygrazed, the unit as a whole will not be excessivelyused. The key grazing area in a management unit is arelatively small area within the grazing unit. This keyarea(s) is used to represent the grazing unit as awhole.

Most plant communities in a grazing unit consist ofseveral plant species in varying amounts. Even thoughthe entire plant community is of concern to manage-ment, to attempt to attain the desired use of everyspecies would be impractical. It is more practical toidentify a single species (or in some situations two orthree) as a key species to serve as a guide to the useof the entire plant community. If the key specieswithin the key grazing area is properly grazed, theentire plant community will not be excessively used.

Characteristics of a key grazing area:• Provides a significant amount, but not necessar-

ily the greatest amount, of the available forage inthe grazing unit.

• Is easily grazed because of even topography,accessible water, and other favorable factorsinfluencing grazing distribution. Small areas ofnatural concentration, such as those immediatelyadjacent to water, salt, or shade, are not keygrazing areas, nor are areas remote from wateror of limited accessibility. However, riparianareas are of special concern when establishingkey grazing areas. Riparian areas are of gener-ally small extent in relation to the surroundinglandscape. These areas represent a significant

resource in terms of forage production, buffer-ing surface water flows, controlling acceler-ated erosion and sedimentation, capturing andtransforming subsurface pollutants, and provid-ing essential wildlife habitat and localbiodiversity. From an ecological basis, theirdesignation as a key grazing area is thereforean important consideration. From thelandowner’s perspective, properly managedriparian areas will be key in retaining flexibilityand control of the property. Table 5–1 is anexample of how and when to consider using ariparian area as a key grazing area.

• Generally consists of a single ecological site orpart thereof.

• Areas of special concern can also be designatedas key areas. Areas of special concern couldinclude habitat for threatened or endangeredspecies, cultural or archeological resources,water quality impaired waterbodies, and criti-cally eroding areas.

• Is usually limited to one per grazing enclosure.More than one key grazing area may be neededfor an unusually large enclosure, enclosureswith riparian areas, enclosures that have veryrough topography or widely spaced waterwhere animals tend to locate, when differentkinds of animals graze the enclosure, or whenthe enclosure is grazed at different seasons.The entire acreage of small enclosures can beconsidered the key grazing area.

Key grazing areas should be• Selected only after careful evaluation of the

current pattern of grazing use in the enclosure.• Selected to meet the objectives and needs of the

resources, livestock, and landowner. Objectivesand needs must meet the FOTG quality criteria.

• Changed when the pattern of grazing use issignificantly modified because of changes inseason of use, kinds or classes of grazing ani-mals, enclosure size, water supplies, or otherfactors that affect grazing distribution.

Characteristics of key species:• Palatability—A relatively higher grazing prefer-

ence is exhibited for it by the kind of grazinganimal and for the planned season of use than forassociated species in the key grazing area.(Very palatable plants that have a negligible



production potential should not be selected askey species except as needed to meet manage-ment objectives or resource goals; e.g., riparianareas.)

• Provides more than 15 percent of the readilyavailable forage in the key grazing area. Aspecies providing less than 15 percent of theavailable forage can be selected as the keyspecies if it has a potential for greater produc-tion or if it is critical to the needs of grazinganimals. A species producing less than 15percent of the forage may also be selected ifnecessary to meet the FOTG quality criteria,the needs of the resource, or the landowner’sobjective. A choice browse species on deerwinter range or in a riparian area are examplesof such a species. Selection of this kind ofspecies usually necessitates a reduction in thestocking rate, and additional measures may be

needed to hasten an increase in the desiredspecies.

• Is consistent with the management objectivesfor the plant community. If the objective is tomaintain or improve the plant community to anear climax state, the key species should beone that is a major component of the historicclimax plant community.

• Is a perennial except where the grazing land ismanaged specifically for annual vegetation orwhere the grazing unit has only annual species ora mixture of annuals of good forage value andperennial species of little or no grazing value.

Key species should be selected only after thedecisionmaker

• Chooses the key grazing area and evaluates thepresent plant community.

Table 5–1 Decision support for consideration of riparian areas as key grazing area*

Factors Riparian area characteristics

Proportion of unit < 5% 5 – 10% > 10%

Livestock accessibility Difficult because of surface Some difficulty, but consis- Readily accessed and consis-rock, steep slopes, debris, tently used by livestock tently used by all classes ofetc. classes able to deal with livestock.

limitations (e.g., yearlings)

Habitat/forage for livestock Livestock do not congregate Livestock congregate for Livestock congregate forfor protection or forage water, protection, or forage water, protection, and foragebased on season of grazing, based on season of grazing, based on season of grazing,geographic location. geographic location. geographic location.

Ecological site Similar to associated upland Different from associated Different from associatedsites. sites; e.g., woody versus sites; e.g., woody versus

herbaceous species. herbaceous species.

Ecological rating No less than associated Less than associated sites. N/Asites.

Decision-support riparian Consider area as an integral Consider area an integral Consider area separate fromarea key grazing area part of the associated sites, part of the associated sites, associated sites; identify astatus but not necessarily as a key and possibly as a key key grazing area within.

grazing area. grazing area.

* Select column based on preponderance of characteristics or a critical characteristic as determined by landowner.

Chapter 5



• Determines the kind of plant community thatwill be the goal of management.

• Gives due consideration to kinds and classes ofgrazing animals and the season of use.

• Thoroughly evaluates the factors affectinggrazing distribution. If only one species ofanimal grazes the unit, a single plant speciesgenerally will suffice as the key species.

(2) Defining proper degree of grazing use for

key species

The objective of grazing management is to maintain ordevelop the kind of plant community within the capa-bility of the land that meets the goals of the decision-maker. The trend, similarity index, and/or rangelandhealth of the rangeland ecological site are the majorconcern. Attaining a specified degree of use of keyplant species in key areas is not an objective. Thedegree of use specified for key species is merely aplanning tool and guideline or reference point bywhich the welfare of the plant community can beevaluated. The following should be considered indefining degree of grazing use:

• Specifications for the degree of use of nativeplant species should be based on local experi-ence of the conservationist and rancher and onthe best available, appropriate research data.Research and experience indicate that theamount of use that native plants can toleratevaries greatly according to the kind of plant,season of use, soil, climate, recent weatherconditions, vigor of the plants, and amount of useto which competing species are subject.

• If a grazing unit is grazed mainly during thedormant season, use may be significantly greaterthan during the growing season.

• The planned or allowable degree of use forbrowse species differs from grass species. Thedegree of use applies to the annual growth oftwigs and leaves within reach of animals. Ifdeciduous browse species are used during thedormant season, the degree of use suggestedapplies to annual twig growth only.

• A significantly greater percentage of annualgrowth can be safely removed from many nativeplants if grazing units are grazed at a high inten-sity for short periods and completely rested forlonger periods. This is particularly true if allplants growing in association are harvestedsomewhat equally. Extreme care must be exer-cised in applying such grazing management to

ensure that vegetation and conditions are similarto those for which specifications are beingestablished. Temporary heavy use must becompatible with the management objectivesand must not contribute to site deterioration.

• If grazing units contain significant amounts ofboth warm- and cool-season forage plants, keyspecies and key grazing areas need to bechanged when the grazing season and grazingperiods are altered within the grazing prescrip-tion.

• If two or more kinds of animals make significantuse of a grazing unit and their forage preferenceor grazing patterns differ, specifications forseason of use and proper grazing use should bedetermined for each kind of animal. This in-cludes selecting appropriate key grazing areasand key species, as needed.

• The degree of use for most grazing units is to beexpressed as the percentage removal, by weight,of the key species in the key grazing area(s).Estimates of the percentage removal are basedon the total production of the key grazing plantsfor the growing season.

• The degree of the use on annual ranges of theMediterranean-type climatic zone can be ex-pressed in pounds of current growth left asresidue.

• For certain perennial plant communities, theappropriate degree of use can also be expressedin pounds per acre of annual growth remaining atthe end of the grazing season if— The plant community is dominated by a

single plant species of high forage value thatis uniformly distributed in the grazing unit.

— The management objective is to perpetuatethat species as dominant.

— The resulting cover provides adequate soiland moisture protection.

— Research or reliable data based on localexperience are available for guidance.

• The amount of growth left on a perennial plant,not the amount removed, is important to thefunctioning of the plant within its community.During an unfavorable growing season, a weak-ened plant may be severely damaged by usethat would not adversely affect it during anormal or favorable growing season. Under theconditions listed the residue procedure can befairly easily applied. In many plant communi-ties, however, species are neither equally



abundant nor uniformly distributed, and they donot have the same ecological status. Thus, aspecification based on weight per acre wouldbe impractical. Until a workable procedure isdeveloped, grazing use specifications are toindicate the percentage of annual growth thatcan be removed from the key plant species inkey grazing areas.

• Monitoring Percent Use of Grazing Species form(exhibit 4–3 in chapter 4) is useful for recordingplanned utilization specifications for key spe-cies in key grazing areas. Data concerningactual grazing use for future comparisons canalso be recorded. Methods for determining thedegree of utilization of key plants are describedin chapter 4, 600.0401(e).

(e) Degree of grazing use asrelated to stocking rates

Because of fluctuations in forage production or loss offorage other than by grazing use, arbitrarily assign-ing a stocking rate at the beginning of a grazingperiod does not ensure attainment of a specificdegree of use. If the specified degree of use is to beattained and trend satisfactorily maintained, stock-ing rates must be adjusted as the amount of availableforage fluctuates.

When determining initial stocking rates, grazingdistribution characteristics of the individual grazingunit must be considered. For example, a Stony HillsRange Site that has steep areas adjacent to a relativelylevel Loamy Upland Range Site generally receives lessgrazing use by cattle than the Loamy Upland RangeSite. The Stony Hills Range Site may produce enoughforage to permit a stocking rate of 2 acres per animalunit per month when it is the only site in a grazing unit.Its grazing use, however, is generally substantiallyless, in the example just described, by the time theLoamy Upland Range Site has been properly used. Thereverse may be true if the grazing animal is sheep orgoats. Therefore, initial stocking rates for a grazingunit should not be based directly on the initial stock-ing rate guides without a careful onsite evaluation offactors affecting grazing use of the entire grazingunit.

Many methods are used to determine the initialstocking rate within a grazing unit. Often the past

stocking history and the trend of the plant commu-nity are the best indicators of a proper stocking rate.The Multi Species Stocking Calculator in the GrazingLands Application (GLA) software is one method fordetermining stocking rates, especially when the areais grazed or browsed by more than one kind of ani-mal. See also Stocking Rate and Forage Value RatingWorksheet in chapter 5, section 3, (exhibit 5–3).

(f) Prescribed grazing schedule

A prescribed grazing schedule is a system in whichtwo or more grazing units are alternately deferred orrested and grazed in a planned sequence over aperiod of years. The period of nongrazing can bethroughout the year or during the growing season ofthe key plants. Generally, deferment implies anongrazing period less than a calendar year, whilerest implies nongrazing for a full year or longer. Theperiod of deferment is set for a critical period forplant germination, establishment, growth, or otherfunction. Grazing management is a tool to balancethe capture of energy by the plants, the harvest ofthat energy by animals, and the conversion of thatenergy into a product that is marketable. This is doneprimarily by balancing the supply of forage with thedemand for that forage. Such systems help to

• Maintain or accelerate improvement in vegeta-tion and facilitate proper use of the forage on allgrazing units.

• Improve efficiency of grazing through uniformuse of all grazing units.

• Stabilize the supply of forage throughout thegrazing season.

• Enhance forage quality to meet livestock andwildlife needs.

• Improve the functioning of the ecological pro-cesses.

• Improve watershed protection.• Enhance wildlife habitat.

Many grazing systems are used in various places.Prescribed grazing is designed to fit the individualoperating unit and to meet the operator's objectivesand the practice specifications. Exhibit 5–6, Pre-scribed Grazing Schedule Worksheet (chapter 5,section 3) may be used in conservation planning.Other formats that contain the necessary informa-tion may also be used. The basic types of grazingmanagement systems follow. Many others can be

Chapter 5



developed to fit specific objectives on specific lands.• Deferred rotation• Rest rotation• High intensity—Low frequency• Short duration

(1) Deferred rotation grazing

Deferred rotation grazing generally consists of multi-pasture, multiherd systems designed to maintain orimprove forage productivity. Stock density is moder-ate, and the length of the grazing period is longer

than the deferment period. An example of a deferredgrazing system would be the four pasture, three herdMer-rill System. This system grazes three herds oflivestock in four grazing units with one unit beingdeferred at all times. The number of livestock isbalanced with the available forage in all four grazingunits. Each grazing unit is deferred about 4 months.In this way the same grazing unit is not grazed thesame time each year. This type of system will repeatitself every 4 years. Figure 5–2 is a conceptual modelof a deferred rotation system.

Figure 5–2 Deferred rotation system model

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The fifth year of this type of system is the same asthe first year. Note that the actual length of timegrazed and deferred depends on the size of the graz-ing units, the size of the herd, and the weather for theyear. The model in figure 5–2 assumes equal size (interms of forage supply) for the four grazing units inthe system.

(2) Rest rotation grazing

Rest rotation grazing consists of either multipasture- multiherd or multipasture - single herd systems.Grazing units are rested or deferred: (1) to restoreplant vigor, (2) to allow for seed development andripening, and (3) to allow seedling establishment.Livestock numbers should be based on the amount offorage that is produced in the pastures that are to be

grazed each year. Figure 5–3 is a model of one ex-ample of five grazing treatments in which growingseason begins first of April and seed ripening occursin July. Sequence of grazing treatments is an entireyear of grazing followed by complete rest the secondgrowing season. This rest period allows plants toregain vigor. During the third growing season, thegrazing unit receives a deferment until seeds of thedesired plants have ripened and then is grazed theremainder of the growing season. The fourth year isan entire growing season of rest to allow for seedlingestablishment. During the fifth growing season,grazing is deferred during the early part of growingseason to further enhance seedling establishmentand then the unit is grazed the remainder of thegrowing season.

Figure 5–3 Rest rotation system model

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Chapter 5



Figure 5–3 Rest rotation system model—Continued

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5.1–12 (190-VI, NRPH, September 1997)

(3) High intensity – low frequency grazing

High intensity - low frequency (HILF) systems aremultipasture - single herd systems. Stock density ishigh to extremely high. The length of the grazingperiod is moderate to short, with a long rest period.Dates for moving livestock are set by the utilizationof the forage. Grazing units are not grazed the sametime of year each year. Figure 5–4 is a conceptualmodel of a HILF grazing system.

In HILF the number of grazing units and grazingcapacity of each unit determine how often if ever thesame grazing unit is grazed during the same period ofthe year.

Figure 5–4 HILF grazing system model

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Chapter 5



(4) Short duration grazing

Short duration grazing is similar to high intensity -low frequency except that the length of the grazingand rest periods are both shorter for the short dura-tion. Utilization, therefore, is less during any givengrazing period. Stock densities are high. Figure 5–5 isa conceptual model of a short duration grazing sys-tem.

In the short duration model, the pattern may neverrepeat itself. The number of grazing units and grazingcapacity of each unit determine how often, if ever, thesame grazing unit is grazed during the same period ofthe year.

In many parts of the United States, livestock cannotbe grazing on the land the entire year. Where snow orother related conditions prevent yearlong grazing, theconcepts of the grazing systems still apply. Figure5–6 is an example of a deferred rotation grazingscheme where the livestock can only be on the graz-ing land from April through October.

Figure 5–5 Short duration grazing system model

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Conservation planning and application on grazinglands are detailed in chapter 11. How each type ofgrazing management system works and the advan-tages and disadvantages of each type must be under-stood. A landowner rarely adopts any grazing man-agement system exactly as it is conceptualized in ahandbook or textbook. The management that getsapplied to the land is a combination of things thatcome closest to achieving the needs of the re-sources, landowner, and livestock. The NRCS

conservationist must understand how livestockgraze, the response of plants to grazing, and howrangelands in an area are impacted by differenttypes of grazing management. Generally, the moreextensive the grazing management, the slower theresponse of the forage resource. The more intensivethe grazing management, the faster the forage re-sponse. However, risk of poor animal performance isincreased. All of these factors must be discussedwith and understood by the landowner.

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Chapter 5



600.0501 Managing grazedforest lands

(a) Principles of forest grazing

Managing a forest to produce forage for livestock,desired wildlife habitat, quality water, quality fisher-ies, timber production, and many other desired forestproducts requires an understanding of the forestecosystem and how it responds to the manager’sdecisions.

Some forest ecosystems managed for timber produc-tion have limited capabilities for livestock grazing.Livestock grazing can cause detrimental effects,such as reduced regeneration of desired woodyspecies, adverse soil compaction, or soil erosion onsteep, highly erodible sites. A decision must be madeto determine if the forest ecosystem will supportlivestock grazing that is designed and managed tomeet the needs of the cooperator and the forestecosystem. Many forests can be grazed where graz-ing management is designed to meet the needs of thesoil, water, air, plants, and animals.

In most forests, solar energy is the major ecologicalcomponent affected in the management process.Solar energy is intercepted by the canopy of thetallest trees. This causes a filtering or reduction ofsolar energy as it penetrates to the next layer ofvegetation, whether it is a midstory of woody plantsor grasses and forbs growing on the forest floor.Managing the forest ecosystem for the desired plantcommunity and the desired production is, in a largepart, accomplished by managing the plant popula-tions in the different stories (overstory, midstory,and understory) to provide the most efficient use ofsolar energy by the desired plants. Managing forestfor forage and timber production requires the TimberManagement Plan and the Prescribed Grazing Planbe coordinated to produce the desired effects on theplant community and all of the ecological compo-nents.

(b) Management of the overstory

The ecological site descriptions for forest land are inSection II of the Field Office Technical Guide(FOTG). They provide information for each forestland ecological site in the field office area. Eachforest land ecological site contains a description ofthe overstory canopy classes that are on the site.Plant species adapted to the site and the amount ofsunlight that penetrates to the ground level are listedfor each canopy class. The description of the under-story composition includes the production (inpounds) of each plant or groups of plants and thetotal production for the canopy class.

As canopy closes from totally open to totally closed(fig. 5–7, a southeast forest site), the understory spe-cies almost completely change from warm-season tocool-season plants. Forage production will be reducedsignificantly as a result of the species compositionchange and the near elimination of sunlight penetra-tion to the ground level.

Management of the overstory canopy with timbermanagement practices is essential to the desiredproduction of forage and understory species. Themidcanopy densities (21 to 35 and 36 to 55 percent)produce a mixture of the warm- and cool-season plantsand in many instances can be managed to maximizetimber production.

Figure 5–7 Canopy classes in a southeast forest site

2,900+lb 1,750 lb 1,200 lb <500 lb

0-20Canopy

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For example, in some southern pine forests thepractice of periodic thinning on a 5- to 6-year rota-tion maintains the desired basal area and canopy oftrees for maximum timber production. This canopyallows substantial forage production for livestockand for grazing and browsing wildlife (fig. 5–8) Thisperiodic thinning is continued until the forest ma-tures. At that time, the forest is clearcut and allowedto regenerate, or it is replanted to the desired treespecies. The forage and browse production is excel-lent until the canopy of the regenerated or plantedtrees closes at about 10 years. Very little understorywill be produced for about 5 years. At about the 15thyear of the new forest, the first thinning cut will bemade. This will again start the maintenance of the 35to 55 percent overstory canopy that maximizestimber production and allows substantial understoryforage production.

If in the above example the periodic cutting cycles arenot made, the canopy will completely close andshade out the understory. Forage production will belimited, and the wildlife habitat for grazing or brows-ing wildlife will be undesirable (fig. 5–9). Pulp woodrotations, where plantings are made and not thinneduntil they are fully harvested, are examples of thistype management. Many privately owned forests arenot managed because of a lack of understanding oftimber management, grazing management, or otherfactors. This causes a canopy closure with the sameresults.

(c) Management of the midstory

Many forests develop a midstory canopy that cancompletely shade the ground level understory (fig.5–10). Even if the overstory is managed to maintainthe desired canopy, a midstory can severely reduce theamount of sunlight reaching the ground level. Theeffects are the same as if the overstory was closed.The understory species composition is changed tothose that are shade tolerant, and forage production isreduced severely.

In this case, if understory production is desired, themanager must reduce the midstory. In many casesprescribed burning can be used to control themidstory species. In others forest improvementshould be planned to manage the midstory to thedesired canopy.

(d) Management of the understory

The understory is made up of grasses, forbs, le-gumes, sedges, vines, and shrubs. When the over-story and the midstory are managed to permit thedesired amount of light to reach the forest floor, aplant community develops that is adapted and sup-ported by the amount of light, water, and nutrientsavailable on the site.

Figure 5–8 Forage production clearcut for naturalregeneration with periodic thinning

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Figure 5–9 Forage production clearcut or naturalregeneration with periodic thinning (com-pared to clearcut or natural regenerationwith no thinning)

Chapter 5



Livestock and wildlife grazing and browsing on thissite select their preferred species. If they arestocked too heavily and for too long a time, theyovergraze the desired species. These species areweakened and reduced in percentage composition,while the less preferred species increase in percent-age composition. If the process is continued, both thepreferred and secondary plant species will be se-verely reduced and replaced with nonpreferredspecies (fig. 5–11 and 5–12).

(40+ years with virtually no forage production)

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Figure 5–10 Forage production clearcut or natural regeneration with periodic thinning (effects of hardwood midstory)

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Figure 5–12 Forage production clearcut or naturalregeneration with periodic thinning(very high forage value rating vs. lowforage value rating)

Figure 5–11 Plant community response to grazingmanagement (36 to 55% canopy)

To correct this grazing management problem, pre-scribed grazing must be applied along with theneeded facilitating practices, such as firebreaks,fences, ponds, wells, pipelines, and troughs. Otherpractices, such as trails, walkways, and roads, maybe needed. Range planting may be needed to providea seed source of the desired species.

Each conservation plan must be tailored to meet theneeds of the soil, water, air, plants and animals, aswell as the needs and objectives of the landowner.

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Figure 5–13 is an example of how a plan can bedeveloped in a southern pine forest to meet the needsof a 50-year timber rotation, livestock production,and improved wildlife habitat. Example 5–1 de-scribes a plan for southern pine forest.

Figure 5–13 Clearcut or natural regeneration using a55-year cutting cycle

Example 5–1 Plan for southern pine forest (refer to figure 5–13)

1. Divide into 11 equal units. Eleven units allow the 50-year production cycle to have one unit cut every 5years and replanted.

2. Install 30-foot-wide fertilized green firebreaks between units (20 acres per section in example). Thesealso serve as roads for managing timber and livestock and for harvesting timber, clearing for fence lines,trails for livestock distribution, and wildlife habitat.

3. Install a 1- or 2-wire electric fence along each firebreak.

4. Install livestock water in each grazing unit.

5. Thin timber each 5 years in all units except those recently planted. First thinning will be at year 15.

6. Clearcut and plant, or harvest to seed trees, one unit each 5 years. Rest new plantings as needed. Seedto native grasses, legumes and forbs if a seed source is needed for establishment. (Severely over-grazed or old cropland fields may need a seed source.)

7. Prescribe burn established stands on a 4-year cycle.

8. Rotate one herd of livestock through the grazable units in a manner that meets the needs of the pine,forage plants, wildlife, and livestock.

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Chapter 5



(e) Western native forest lands

Many western forests have naturally open or sa-vanna-like aspect with highly productive understoryplant communities. Others naturally develop densecanopies that at maturity will eliminate nearly allunderstory vegetation.

Savanna forest land overstories are typically managedby selectively removing mature trees for lumber, on aperiodic basis, while managing the understory commu-nity for wildlife habitat and forage.

Dense forest lands only develop significant understoryvegetation after stand removing fire or clearcutting ofthe site occurs. During this open canopy period, forestreseeding or natural regeneration causes the commu-nity to transition back to dense forest. This transitionperiod normally lasts from 10 to 20 years, and, whileopen, these areas can provide an important foragesource for livestock and wildlife. Forest managementgenerally adds new clearcuts to the landscape on aperiodic basis while open forest lands transition backto closed canopies on a planned schedule. This en-sures that a stable transitory forage resource isalways available at some locations on the operationfor wildlife and livestock use.

Conservation planning activities must consider boththe forest resource and the wildlife and forage re-sources available to the landowner. Close coordinationis needed to optimize the economic gain from theseresources while protecting the ecological integrity anddiversity of the management area.

(1) Managing grazed forest lands for multiple

benefits

Many native forest lands in the Western United Statesproduce multiple forest products including timber,grazing for wildlife and livestock, habitat for manyspecies of wildlife, sustained summer streamflows,and pure water. Careful resource management isrequired to ensure that proper balance is achieved andthat multiple resource values are sustained.

These grazed forest lands range from high mountainspruce-fir ecosystems, to Douglas fir stands at middleelevations, to the dryer savanna-like mixed fir-pine andpure pine sites.

A typical grazed forest land ecosystem in the West-ern United States would be a ponderosa pine, bitter-brush, Idaho fescue ecological site. This site typi-cally is dominated by an overstory of ponderosa pine.Site indices (SI) can range from a low of less than 40to more than 120. Wood products are harvested usinguneven-aged management techniques. Mature andovermature trees are selectively removed from thestand on a scheduled basis. They are naturally re-placed in the stand by younger trees that are releasedto grow more rapidly once the older competition isremoved.

Fire played an important role in this community byperiodically thinning out part of the younger treeswhile causing little damage to the older ones becauseof their insulated, fire resistant bark. This created anopen, savanna-like aspect to the communities, creatingsome of the most productive wildlife areas in thecountry, especially during the winter and spring.

Understory vegetation is dominated by Idaho fescueand antelope bitterbrush. These species provide excel-lent forage and browse for deer and elk, as well asdomestic cattle and sheep. Production in the under-story is directly related to the density of the overstorycanopy.

Even though fire played an important role and is anatural part of these communities, people have aggres-sively removed fire, causing major changes in thestructure and health of many of these forest communi-ties. Dog-hair thickets of young ponderosa pine nowoccupy the middle canopy layer, effectively shadingout the understory vegetation while creating the po-tential for catastrophic, stand removing crown fire.

Management of these communities requires a knowl-edge of both the forest resource and the understorygrazing resource. Forest products, such as logs,fence posts, and firewood, can be harvested periodi-cally while routinely harvesting the forage for theproduction of food and fiber.

The first step in managing the forest resource on a siteis to complete an inventory of the various timberstands on a site and by determining the growth poten-tial or SI for each stand. A rule-of-thumb for standmanagement is as follows:



SI > 100 Thin trees to a D+3 to D+6 spacing.Remove merchantable products aspart of this thinning when feasible.

SI 80 to 100 Thin trees to a D+5 to D+8 spacing.Remove merchantable products aspart of this thinning when feasible.

SI < 80 Thin trees to a D+6 to D+9 spacing.Remove merchantable products aspart of this thinning when feasible.

For optimum grazing in these stands, add 1 or 2 feet tothe spacing.

The D+ spacing is determined by measuring the diam-eter at breast height of each leave tree converting thisnumber to feet and then adding the + factor to estab-lish to total spacing for that individual tree for opti-mum growth. Select the next leave tree at the perim-eter of this thinned area and repeat the process. Astimber products are removed from the stand, addi-tional thinning may be necessary to keep the standwell managed. Priority should be given for the re-moval of deformed and diseased trees during thethinning process.

Grazing management of the understory vegetationfollows the same principles as for rangeland manage-ment. A grazing management plan should be devel-oped for each grazing unit. Prescribed grazing is theNational Conservation Practice Standard to be fol-lowed when designing practices for grazed forestlands.

Wildlife use in these areas is often significant, andavailable forage must be allocated accordingly. Graz-ing plans must also consider existing and planned treeplantations to provide protection during periods whenseedlings could be damaged by grazing animals.

(f) Inventorying grazed forest

As described above, the amount and nature of theunderstory vegetation in forest are highly responsiveto the amount and duration of shade provided by theoverstory and midstory canopy. Significant changes in

kinds and abundance of plants occur as the canopychanges, often regardless of grazing use. Some suchchanges occur slowly and gradually as a result ofnormal changes in tree size and spacing. Otherchanges occur dramatically and quickly, followingintensive woodland harvest, thinning, or fire. Signifi-cant changes do result from grazing use, however, andthe understory can often be extensively modifiedthrough the manipulation of grazing animals.

For these reasons the forage value rating of grazableforest is not an ecological evaluation of the under-story. It is a utilitarian rating of the existing foragevalue of a specific tract of grazable forest for specificlivestock or wildlife. The landowner or manager needsto understand the current species composition andproduction in relation to their desired use of the landby specific animals.

(1) Procedure for determining forage value

rating

Forage value ratings are to be based on the percent-age, by air-dry weight, of the existing understoryplant community (below 4.5 feet) made up of pre-ferred and desirable plant species. Four value ratingsare recognized:

Forage value rating Minimum percentage

Very high 50 preferred + desirable = 90

High 30 preferred + desirable = 60

Moderate 10 preferred + desirable = 30

Low Less than 10 preferred

Introduced species should be rated according to theirpreference by the animal species of concern andincluded in the determination of forage value rating.See Worksheet for Determining Forage Value Rating(exhibit 5–4) in section 3 of this chapter.

The production of understory plants can vary greatlyeven within the same canopy class. Therefore, if theforage value rating obtained by considering only thepercentage of preferred plants is very high or high,but the production is less than that expected for theexisting canopy, reduce the final forage value ratingone or more classes to reflect the correct value.

Chapter 5



600.0502 Managing natu-ralized or native pasture

Naturalized pasture is land that was forest land inhistoric climax, but is being managed primarily for theproduction of forage rather than the production ofwood products. It is managed for forage productionwith only the application of grazing managementprinciples. The absence of the application of fertilizer,lime, and other agronomic type practices distinguishthis land use from pasture.

Because naturalized pasture was forest in its naturalstate, it will naturally evolve back to a forest domi-nated plant community. For the site to be maintainedas naturalized pasture, a form of brush managementis normally planned to suppress the tree and shrubcomponent of the site. Prescribed burning, mechani-cal, herbicides, or biological control need to beplanned, designed, and applied to create the desiredplant community to meet the resource criteria.

Prescribed grazing is planned to meet the needs ofthe plant community and the livestock and wildlife ofconcern. The grazing management principles appli-cable to grazed range and pasture are applicable tonaturalized pasture. The prescribed grazing planmust address solving all of the resource problemsand concerns identified in the inventory and problemidentification process where either livestock orwildlife is a contributor to the cause of the problem.

Range planting may be needed to establish the de-sired plant community when a seed source of thedesired species is not evident. Facilitating practices,such as firebreaks, fences, and livestock waterdevelopment practices are planned as needed.

NRCS assists cooperators to understand the ecology oftheir naturalized or native pasture. They assist themin inventorying and evaluating the naturalized pas-ture productivity and in determining the suitability ofpresent and potential vegetation for the appropriateneeds and uses. The Forest Ecological Site Descrip-tion is to be used as the naturalized or native pasture

interpretative unit. The understory descriptions andinterpretations, as described in the Forest EcologicalSite Description, provide the needed information forinventory.

Forage value ratings should be determined to providean index for the landowner and manager to under-stand the value of the present plant community inmeeting the needs of their livestock and wildlife.





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Section 2 Managing Forage Crops and Pasture

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Chapter 5

5.2–i(190-vi, NRPH, September 1997)


Section 2 Managing Forage Crop and Pasture Lands

Contents: 600.0503 General 5.2–1

600.0504 Managing improved pasture 5.2–2

(a) Seasonal distribution of growth or availability of pasture ................... 5.2–3

(b) Forage growth response to the grazing animal ...................................... 5.2–9

(c) Selective (spot) grazing of pastures ...................................................... 5.2–17

600.0505 Conservation practices for pasture 5.2–19

(a) Harvest management practice—Prescribed grazing ........................... 5.2–19

(b) Accelerating practice—Nutrient management .................................... 5.2–30

(c) Accelerating practice—Pasture planting .............................................. 5.2–35

(d) Accelerating practice—Prescribed burning ......................................... 5.2–37

(e) Accelerating practice—Irrigation water management ........................ 5.2–38

(f) Facilitating practice—Water development ........................................... 5.2–39

(g) Facilitating practice—Stock walkways or trails .................................. 5.2–43

(h) Facilitating practice—Fencing ............................................................... 5.2–45

(i) Accelerating and facilitating practice—Pasture clipping ................... 5.2–48

600.0506 Managing forage cropland 5.2–49

(a) Forage crop production .......................................................................... 5.2–49

600.0507 Vegetative conservation practices for forage cropland 5.2–54

(a) Harvest management practice—Forage harvest management .......... 5.2–54

(b) Accelerating practice—Nutrient management .................................... 5.2–59

(c) Accelerating practice—Hay planting .................................................... 5.2–65

(d) Accelerating practice—Irrigation water management ........................ 5.2–69

(e) Accelerating practice—Soil amendment application .......................... 5.2–74

(f) Acceleratingpractice—Weed control .................................................... 5.2–75

(g) Accelerating practice—Disease and herbivory control ...................... 5.2–77

(h) Facilitating practice—Conservation crop rotation ............................. 5.2–79

600.0508 Conclusion 5.2–83


5.2–ii (190-vi, NRPH, September 1997)

Tables Table 5–2 Estimated monthly availability of forage for grazing 5.2–4

Table 5–3 Suggested residual grazing heights for major pasture 5.2–12

forage species

Table 5–4 Rotational pasture estimated utilization rates 5.2–23

Table 5–5 Seasonal total of nitrogen fixation by forage legumes 5.2–33

and legume-grass mixtures

Table 5–6 Silage storage structure forage moisture suitability 5.2–55

Table 5–7 Minimum number of plants per square foot to achieve 5.2–68

a full stand

Table 5–8 Total seasonal consumptive use of water by alfalfa in 5.2–70

Western United States

Table 5–9 Seasonal consumptive-use requirements of some 5.2–70

forage crops

Table 5–10 Classification of irrigation water based on boron and 5.2–71

chloride content

Table 5–11 Boron tolerance limits for some forage crops 5.2–72

Figures Figure 5–14 Gulf Coast seasonal distribution of growth and 5.2–5

availability of pasture

Figure 5–15 Upper South seasonal distribution of growth and 5.2–6


Figure 5–16 Upper Midwest seasonal distribution of growth and 5.2–7


Figure 5–17 Livestock demand versus forage growth and availability 5.2–8

during the grazing season where livestock were placed

on pasture April 1

Figure 5–18 Seasonal distribution of growth of cool-season pasture 5.2–8

and total production for 1987 and 1988 in southern

New York

Chapter 5

5.2–iii(190-vi, NRPH, September 1997)


Figure 5–19 Growth stages of grasses and legumes and their effect 5.2–9

on intake, digestibility, and dry matter production

Figure 5–20 Leaf growth rate changes based on residual leaf area 5.2–10

left as result of grazing height

Figure 5–21 Differences in forage plant morphology from one 5.2–11

species to the next change their response to grazing

height

Figure 5–22 Response of a nonjointed grass like Kentucky 5.2–13

bluegrass compared to a jointed grass like switchgrass

Figure 5–23 Changes in species composition over a 5-year period 5.2–14

under different stocking regimes

Figure 5–24 Differences in regrowth of white clover as result 5.2–15

of grazing height; removal of the grass canopy favors

the growth of white clover

Figure 5–25 Variable recovery period 5.2–16

Figure 5–26 Relationship of output per head versus output per 5.2–19

acre based on grazing pressure or its reciprocal,

forage allowance

Figure 5–27 Available forage requirements for different classes 5.2–21

and ages of livestock

Figure 5–28 Dry matter intake of dairy cows based on dry matter 5.2–22

digestibility and daily milk production

Figure 5–29 Forage utilization as it affects forage intake 5.2–23

Figure 5–30 Three classes of stocking methods and their 5.2–25

associated stocking method

Figure 5–31 Nutrient cycling in a pasture ecosystem 5.2–31

Figure 5–32 Yield response curve to indicated range of plant 5.2–32

available nutrients from soil test results

Figure 5–33 Typical water budget showing where the seasonal 5.2–38

need to irrigate occurs and the magnitude of that need

Figure 5–34 Spring development showing collection system, 5.2–40

pipeline to and from trough, and trough


5.2–iv (190-vi, NRPH, September 1997)

Figure 5–35 Pasture pump installation 5.2–42

Figure 5–36 Three-gate opening 5.2–44

Figure 5–37 Amount of dry matter loss of harvested forages 5.2–50

during harvest operations and storage

Figure 5–38 Forage integration model 5.2–51

Figure 5–39 Forage management planning elements and how they 5.2–53

interact with one another

Figure 5–40 Relative feed value and livestock classes 5.2–54

Figure 5–41 Response to fertilizer by two forage suitability groups 5.2–59

Figure 5–42 Maximum economic yield 5.2–60

Figure 5–43 Grass response to nitrogen fertilizer 5.2–62

Figure 5–44 Influence of potassium available in the soil to 5.2–64

potassium content in grasses

Figure 5–45 USDA classification of irrigation water 5.2–71

Figure 5–46 Assessing salinity hazards using conventional irriation 5.2–73

Example Example 5–3 Crop rotation worksheet 5.2–81

Chapter 5

5.2–1(190-vi, NRPH, September 1997)

Management of Grazing Lands National Range and Pasture HandbookSection 2 Managing Forage Cropand Pasture Lands

600.0503 General

Efficient use of forage crop and pasture lands requiresunderstanding two basic components of foragegrowth:

• Each forage's physiological and morphologicalattributes must be understood.

• How the forage responds to competing plants,climate, soil, machine harvest timing and fre-quency, human determined inputs, and grazingtiming, duration, pressure, and frequency mustbe known.

Agronomic inputs into forage crop production andimproved pastures are seeding mixtures used, selec-tion of adapted cultivars resistant to local diseases orinsects, fertilizer, pasture clipping, planting proce-dures used, soil amendments, pest control, drainage,irrigation, and other crops, if any, used in rotation withforage crop. Animal nutrition variables are off-farmfeed supplements, producer production goals, and thekind, number, and class of livestock being fed.

The growth habit characteristics, soil chemical andphysical preferences, and palatability characteristicsamong agronomic forage crops vary widely. Thiscreates a myriad of shifts in plant species compositionon forage crop and pasture lands even in so-calledmonoculture fields. Depending on which species isfavored based on climatic and soil conditions and themanagement the forage stand receives, some specieslive on and others die out. The shift in forage speciescomposition is swift even under the survival of thefittest scenario. However, a farmer with a plow orsprayer and a planter can cause one crop to disappearand another crop appear in a few days. The sameproducer can also cause radical changes for good orharm with a herd or flock of livestock.

All management decisions, whether they be agro-nomic, economic, or animal nutrition driven, must bedone within the constraints imposed by the manage-ment unit ecosystem at any given moment. If theconstraints are ignored, the improvement practiceultimately fails. No conservation or improvementpractice should be applied without analyzing whatdrives the system.

On pastured lands, once climate and soil factorsaffecting forage growth and production are accountedfor, the system is driven by the grazing managementregime applied. If producers are unwilling to changetheir customary approach to grazing management,agronomic solutions to forage growth enhancementwill only be as effective as that grazing managementregime allows. If the forages are overgrazed, agro-nomic attempts to improve forage production arelikely to fail, or the improvement is only marginal. Theaccompanying environmental problems resulting fromthe weakened plant community will be affected littleas well.

On cropped (machine harvested) lands, once climateand soil factors affecting forage growth and produc-tion are accounted for, the system is driven by plantingand harvesting regimes (by grazing animal or ma-chine). If either is done poorly because of impropertiming or technique, all the other agronomic inputsadd more to the cost of production, but little to im-proved forage or livestock production. In the mean-time environmental problems created by this misman-agement continue to mount.

National Range and Pasture HandbookManagement of Grazing Lands

5.2–2 (190-vi, NRPH, September 1997)

Chapter 5

600.0504 Managingimproved pasture

Pasture is harvested principally by the grazing animal;therefore, it must be managed differently than haylandand cropland that are harvested primarily by machine.Seasonal availability or distribution of forage growth isvital to allocating enough feed to the grazing animalwithout wasting it or overgrazing it. A growing forageis a perishable commodity. As it matures, it lowers invalue nutritionally. This is especially true after seed-head emergence on grasses or initial flowering oflegumes and forbs.

Stored forages (roughages) are a more nutritionallystable commodity if stored properly. However, theygenerally are of lower nutritional value because theyare harvested at a later stage of maturity than are themore timely grazed pastures. When an animal eatsstanding forage, there is no loss of leaves and no lossof vitamins and dry matter. The forage is directlyingested rather than curing in a field or barn or fer-menting in a silo or forage bag, and they can select thechoicest forage available. Therefore, pasture manage-ment must recognize that ups and downs occur inforage quality and quantity. Pasture must be stocked inconcert with growth and availability of forages. If thisis done, forage quality will be consistently near itsoptimum for the time of the year.

Pastured land also differs from cropland and haylandin the way plant material is removed. The grazinganimal tends to graze from the top down, but it doesthis over a period of time. They take a bite, move on,take a bite off another area, and proceed across thepasture selecting what appeals to them. Depending onhow much control the producer exerts, the livestockmay have free rein to explore the whole managementunit or a very small part of it. They may be able toreturn to the same spot continually throughout thegrazing season or be allowed to return only within afew hours and then be off for several days or weeks. Inany case, more residual material is always left behindthan where forage crops are harvested mechanicallyunless heavily overstocked or stocked for prolongedperiods.

After initial green-up pasture forages generally are lessdependent on stored food reserves to continue growththan are machine harvested forages. They still havephotosynthetic area to continue producing simplesugars that are synthesized into plant food. Machineharvested forages are dependent on food reserves andbasal growing points or axillary buds held below thecutting bar to generate new growth. After machineharvest few or no green leaves are left to carry onphotosynthetic activity.

The distribution of plant tissue removal is also quitevariable on pasture unless severely overgrazed orrationed tightly under a multiple paddock system. Thelatter mimics machine harvest in uniformity of re-moval if managed well. With machine harvest allforage is removed from the management unit uni-formly. This variation in plant removal by grazingresults from a number of factors:

• Selectivity of the grazing animal• Differences in palatability among the plant

species present• Differences in maturity and palatability as a

result of the previous selective grazing• Steepness of the terrain• Presence of barriers that affect livestock move-

ment or behavior• Distance to water• Distance to shade when present

Another way pastured lands differ from cropland andhayland is that nutrients are recycled within theirboundaries. Most of the nutrients consumed are usedto maintain the animal and are excreted. They may notbe distributed evenly, but they are continually re-turned as long as the pasture is occupied by livestock.On hayland and cropland, all nutrients in the harvestedcrop leave the field. They may or may not be replacedby manure or fertilizer nutrients.

Nutrient removal from pasture as animal products isrelatively low. A thousand pounds of milk removesonly 6 pounds of nitrogen; 2 pounds each of phospho-rus, potassium, and calcium; and negligible amounts ofother minerals. A thousand pounds of beef removes 27pounds of nitrogen, 8 pounds of phosphorus, 2 poundsof potassium, and 13 pounds of calcium. Even underthe best conditions, 1,000 pounds of stocker beef is allthat can be produced per acre per year. More com-monly, gains per acre on good pasture can range from250 pounds per acre to 750 pounds per acre. If the

Chapter 5



livestock are fed any supplemental feed or minerals atall while on pasture, no net loss occurs in fertility leveland a gain in the less mobile nutrients can occur. Highproducing dairy cattle on pasture typically are fedstored forages and concentrates to balance their dietfor optimum milk production. Import of nutrients fromthese supplements tend to match or exceed export ofnutrients as milk production. See accelerating prac-tice, nutrient management.

(a) Seasonal distribution ofgrowth or availability ofpasture

Pasture, in the broader sense of the word, occurs onall three land uses that make up forage crop andpasture lands. Therefore, when allocating standingforage to grazing livestock, more than just when theforage is growing and at what rate must be considered.Often the forage's growth curve does not dictate theforage's grazing availability, a management decisiondoes. For example, forages can be stockpiled. Theyare allowed to grow and accumulate mass and thengrazed at a later date even after the growing seasonhas ended. Forages that retain their leaves and nutri-tional value are preferred for stockpiling.

Crop residue can also be grazed. Again, a seasonalgrowth curve is of no value in developing a livestockfeed budget that uses crop residue. Instead, what isimportant is: When is it available? Cornstalk residue,for instance, becomes available after harvest and has auseful life of about 60 to 90 days before weathering ortrampling diminishes its usefulness as a feedstuff(table 5–2). This is, of course, dependent on rainfalland temperature. Low rainfall coupled with very coldtemperatures prolongs its nutritional quality. Decom-position is arrested or slowed, and no mud is availableto be trampled onto the residue.

A basic tool needed to manage pasture and allocate itto livestock is the seasonal distribution of growth oravailability table or family of curves that are developedfor your climatic area. Three examples of seasonaldistribution of growth or availability curves are shownfor the Gulf Coast, Upper South, and Upper Midwest infigures 5–14, 5–15, and 5–16. Note change in species aslatitude changes. Also note for a crop like alfalfa howthe growing season length changes with latitude, shortin the north and long in the south.

Seasonal distribution of growth or availability curvesshould not only be identified by species, but by grow-ing season length as well. Other important factors arethe beginning and end dates of the growing season andthe distribution of rainfall and growing degree daysduring the growing season. Two areas of the countrywith the same growing season length can have differ-ent distribution of growth responses due to differ-ences in rainfall patterns and how fast it warms upafter the growing season begins. A mid-continentclimate is slower to warm up than one along the Atlan-tic seacoast where the Gulf Stream can quickly warmthe region. When the same growing season lengthregion has different beginning and ending dates as itcrosses the continent, changes in day length responsealso take place where long or short day plants areimportant forages. Long day plants tend to grow fasterto make up for lost time where the growing seasonstarts later in the spring. For all these reasons, it isbest to use seasonal distribution of growth and avail-ability curves developed in your region. Do not usedistribution tables from regions that have greatlydiffering seasonal rainfall and cumulative growingdegree day patterns.

Note in figures 5–14, 5–15, and 5–16 how the differentforages are available for grazing during different partsof the year. Warm-season grasses, such asbermudagrass, bahiagrass, pearl millet, big bluestem,switchgrass, and sorghum/sudan, produce duringwarm weather. Cool-season grasses and legumesproduce most of their growth in the cool weather ofspring and fall. Cool-season winter annuals actuallyproduce grazable forage in the Gulf Coast States andas far north as Maryland and Kansas during the wintermonths. Year-round grazing is possible over much ofthe United States using a combination of these foragesby taking advantage of their different availabilityperiods. Cool-season forages can be relied on duringthe early and late parts of the year. When they godormant or grow slowly during the middle of the year,warm-season forages can be relied on to fill in thegrazable forage gap.



Chapter 5

Crop residue, such as cornstalks, can be grazed afterthe crop is harvested. The proportion of the acreagedevoted to either warm- or cool-season forages, or aninterseeding of warm- and cool-season forages, de-pends of the livestock demand fluctuations of the landunit being planned and the ratio of warm-to-coolweather of the climate in which the land unit is lo-cated. Crop residue can also be grazed where available

Table 5–2 Estimated monthly availability of forage for grazing 1/

Type of pasture - - - - - - - - - - - - - - Percentage available, by month - - - - - - - - - - - - - -May June July Aug. Sep. Oct. Nov. Dec.

Kentucky bluegrass-white clover, unimproved 25 30 10 5 10 10 5 —Kentucky bluegrass-white clover + N, P 35 35 8 5 10 4 3 —-

Renovated (continuous grazing)Birdsfoot trefoil-grass 10 25 25 20 10 2/ 5 2/ 5 —Birdsfoot trefoil -grass, deferred for midsummer grazing —- 15 35 25 15 2/ 5 2/ 5 —

Tall grasses + N 3/ 30 30 10 5 10 10 5 —Tall grasses + N, deferred for fall grazing 3/ 30 30 —- —- —- 25 15 —-

Renovated (rotational grazing)Alfalfa with smooth bromegrass or orchardgrass 20 25 25 15 5 5 2/ 5 2/ —-

SupplementalSudangrass or sorghum-sudan hybrids —- —- 40 40 15 —- 4/ 5 —-Sudangrass or sorghum-sudan hybrids, deferred for fall —- —- —- —- —- 100 5/

and winter grazingWinter rye 50 20 —- —- 5 15 10 —

MiscellaneousMeadow aftermath-following one cutting —- 20 30 25 5 2/ 15 2/ 5 —Meadow aftermath-following one cutting, to be plowed —- 20 30 10 20 20 —- —Meadow aftermath-following two cuttings —- —- 10 35 25 2/ 25 2/ 5 —Meadow aftermath-following two cuttings, to be plowed —- —- 10 25 35 30 — —Cornstalks —- —- —- —- —- 100 —- —-

1/ Source: Schaller (1967). Compiled originally by W.F. Wedin, Agronomy Department, Iowa State University.2/ Allowances have been made for winter hardening of legume from about September 15 to October 15.3/ Smooth bromegrass, orchardgrass, tall fescue, reed canarygrass, or combinations.4/ Grazing must be avoided between first frost and definite killing frosts because of prussic acid content in regrowth shoots.5/ All forage becomes immediately available, but may be gazed for up to 3 months if quality and supply are sufficient.

and where perimeter fences exist around the manage-ment unit. Another alternative is to stockpile foragesthat keep their quality well and withhold from live-stock until a livestock demand as the seasonprogresses. This is typical of a stocker or cow-calfoperation where animals are growing. As they gain,animal units mount up.

Chapter 5



Figure 5–14 Gulf Coast seasonal distribution of growth and availability of pasture (from Ball, et al. 1991)

Forage

species

Bahiagrass

bermudagrass

Pearl millet

Rye

Wheat

Annual ryegrass

Alfalfa

Arrowleaf clover

Crimson clover

J F M A M J J SA O N D

Normal forage availability by months

Hybrid



Chapter 5

Figure 5–15 Upper South seasonal distribution of growth and availability of pasture (from Ball, et al. 1991)

Forage

species

bermudagrass

Big bluestem

Pearl millet

Tall fescue

Ordhardgrass

Kentucky bluegrass

Alfalfa

Red clover

Birdsfoot trefoil

Ladino clover

J F M A M J J SA O N D


Hybrid

Chapter 5



Figure 5–16 Upper Midwest seasonal distribution of growth and availability of pasture (adapted from Undersander, et al. 1991)

Forage

species

Orchardgrass

Quackgrass

Smooth brome

Timothy

Tall fescue

Reed canary

Sorghum/sudan

Switchgrass

Big bluestem

Alfalfa

Birdsfoot trefoil

Red clover

Sweet clover

Alsike clover

Ladino clover

Winter rye

Oats, spring sown

Corn stalks

KentuckyBluegrass

A M J J A S O N D




Chapter 5

Figure 5–17 illustrates that a cool-season forage pas-ture produces too much forage early-on, and, as thesummer heat arrives, begins to produce too little tomeet livestock demand. The use of different forageseither in the same pasture or in separate pasturesallows the livestock producer to maintain enoughforage on-offer to his livestock throughout the grazingseason. Using stockpiled forages or growing winterannuals can extend the grazing season past that of theperennial cool- and warm-season forages’ growingseasons illustrated in figure 5–17. If grazed rotation-ally, the warm-season grass could also be stockpiled(not shown) and grazed later in the fall as a standingcured forage if not weathered too badly. The figure

also shows that with both the cool-season and warm-season in the pasture system, surplus pasture is avail-able in mid-summer. The excess could be harvested ashay or stockpiled for grazing, depending on operatorpreference. Meanwhile, at the end of the grazingseason, the stockpiled cool-season forage would needto be supplemented with some stored forage if thewarm-season grass was not stockpiled for use inNovember. This is just one example of how the distri-bution of growth or availability graphs can be used tohelp formulate a pasture system for a livestock opera-tor.

A drawback of the graphs or growth curves is theirlack of specific numbers. They are useful because theyquickly point out peaks and troughs of growth oravailability. Tables are more useful in doing detailedpasture budgeting. They use units, such as monthlypercentage of total annual production, tons of drymatter per acre per month, animal unit months peracre per month, or acres needed per animal unit permonth. Table 5–2 illustrates the use of monthly per-centage of total annual production. It is the mostuseful form because the other three assume a fixedannual production value. In regions where soil vari-ability, climate variability, past crop managementhistory, or a combination of these vary widely fromfarm to farm or field to field, annual forage yields canrange widely from one site to the next and from oneseason to the next. This is illustrated in figure 5–18.

Figure 5–17 Livestock demand versus forage growth andavailability during the grazing season wherelivestock were placed on pasture April 1(adapted from Barnes, et al. 1995)

Figure 5–18 Seasonal distribution of growth of cool-season pasture and total production for 1987and 1988 in southern New York (fromEmmick and Fox 1993)

70

0 l

b s

teers p

er a

cre

Months during season

2

1

0April May June July Aug. Sept. Oct. Nov.

Cool seasonforage produced

Forage needed

700 l

b s

teers p

er a

cre

Months during season

2

1

0April May June July Aug. Sept. Oct. Nov.

Cool seasonforage produced

Forage needed

Warm seasonforage produced

Stockpiled cool seasonforage produced

2000180016001400

12001000800600400200

0A M J J A S O N

Month

% of

total yield

% 13 25

56 % 44 %

18 11 11 14 8

Yie

ld i

n l

b/a

c

19871988

8600 lb/ac6800 lb/ac

Chapter 5



Note that the distribution of forage production re-mained constant, but forage on-offer was quite differ-ent between years as was total annual production. Thefactors listed do impact the percentage distributionthroughout the season as well, but less so. Given theyear to year variability inherent with a living system,think of the percentages as being averaged, somewhatinexact constants for doing pasture budgets. Some areconstructed from long-term averages. Others comefrom limited short-term research studies. Therefore,expect some variation from year to year.

The monthly percentage of total annual productionwhen multiplied times the estimated total annualproduction indicates the amount of forage grown oravailable during that month. If forage demand bygrazing livestock for that month is known or can beestimated, the acres of pasture needed to feed thelivestock that month will be known. This is the es-sence of a pasture budget. It allocates enough pastureforage to meet forage demand for the livestock beingpastured. Therefore, seasonal distribution of growthand availability information is a crucial tool in doing apasture budget and an overall livestock feed budgetfor the year. The livestock feed budget is necessary todo whole farm planning of a livestock producingmanagement unit. It dictates ratio of pasture to crop-land and hayland and the choice and balance of cropsin crop rotations planned on cropland. For instance,an operator may decide to plant a summer annual oncropland to meet a deficit in forage production on thepermanent pasture acres. The planner and farmer needto work that crop into the rest of the crop rotation. Ifnot, then another alternative, such as grazing some haycrop acres after first cut, needs exploring.

(b) Forage growth response to thegrazing animal

No matter what stocking method is used to allocateforage to grazing livestock, the goal should be to keeppasture forage in a vegetative growth stage. This iswhen the forage is at its best nutritionally and photo-synthetically most active. Cool-season forages losesome of their digestibility especially when allowed togo to head or flower (fig. 5–19). They produce moredry matter, but livestock intake is depressed. In fact,this is why mature forage areas are avoided by live-stock in fields that have been spot grazed. They go tothe choice spots where growth is still highly vegeta-tive, preflower for tap-rooted legumes or pre-bootstage for grasses.

Warm-season grass loss of digestibility is much lower.However, many are lower in digestibility than cool-season forages to start with, so the warm-seasongrasses must be harvested even more timely. In com-paring pasture to stored forage production, it is criticalthat the planner not become hung up on total drymatter production. Pasture may produce less total drymatter than machine harvested forage acres. However,it produces a higher quality feed than machine har-vested forage acres and similar total digestible drymatter if livestock demand and seasonal forage pro-duction are closely matched. Most stored forages arecut after grass heading and initial legume flowering.

Figure 5–19 Growth stages of grasses and legumes andtheir effect on intake, digestibility, and drymatter production (from Blaser, et al. 1986)

Grasses Leafy Boot Heading BloomLegumes Leafy Prebud Bud Bloom

Growth stages

Dig

esti

bil

ity p

ercen

t

Inta

ke p

ercen

t o

f b

od

y w

eig

ht

Dry m

att

er -

to

ns/a

cre

0.5

1.0

1.5

2.0

Intake

YieldDigestibility

80

703%

2%

1%

60

50



Chapter 5

Forages grazed too close lose green leaf area belowthat needed to optimally capture sunlight. This delaysregrowth and uses stored food reserves. The growthcurves are shown in figure 5–20. If grazed too closerepeatedly, the forage plant becomes weaker as foodreserves run low. Death can result if other stresses orphysical damage from hoof action occurs. Foragesdiffer greatly in their ability to withstand close grazing.Forages that have growing points and some leaf areabelow the grazing height can withstand close grazing(fig. 5–21). Examples of these are Kentucky bluegrass,bahiagrass, bermudagrass, white clover, and tallfescue. Forages that have rhizomes and/or stolons justbelow and above the ground surface respectively, alsohave a greater chance of surviving close grazing. Bothprostrate stems store food reserves and can initiatenew shoots and roots at nodes from those reserves.Close grazed pastures where these forages are climati-cally adapted will be dominated by these species ifintroduced there initially. They simply have the com-petitive advantage in that situation.

Grazing height is therefore the critical parameter inpasture management where regrowth is possible anddesired. Different forage species require differentresidual heights to maintain adequate leaf area tointercept full sunlight. For most forages a leaf areaindex (LAI, leaf area to ground surface ratio) of 3 to 4will intercept enough sunlight to maintain maximumphotosynthetic activity. The height at which this isattained varies from species to species. White cloverand bermudagrass can attain this at a height of only 1inch. Meanwhile, orchardgrass and tall fescue wouldneed from 1.5 to 2 inches. Table 5–3 lists suggestedresidual grazing heights for major pasture species.

If grazed to the minimum height required to maintainfull light interception and maximum growth rate at alltimes, as shown in figure 5–20(a), the grazed stubble ishigher (schematic inset). Plant or stem density tendsto be higher as a result as well. This is necessarywhere pastures are to be stocked continuously. Be-cause cattle are there continuously, there is no recov-ery period to allow forages to increase leaf area beforethey may be grazed again.

Figure 5–20 Leaf growth rate changes based on residualleaf area left as result of grazing height (fromHodgson 1990)

Where pastures are rotationally stocked, forages canbe grazed closer, as shown in figure 5–20(b). However,enough residual leaf area must be left behind to keepplants in a vigorous, fast growth state. Note in thisexample the recovery period to the maximum growthrate is about 16 days. A few more days then would beneeded to allow forages to grow to the desired avail-able forage mass needed for the class of livestockbeing fed. Do not interpret figure 5–20 to be graphsshowing mass accumulation.

Needed for con-tinuous grazing

Allowable forrotational grazing

Result of heavyclose grazing(rotational orcontinuous)

100

50

100

50

100

50

(a)

(b)

(c)

1 2 3 4 5

Time after defoliation (weeks)

Leaf

gro

wth

rate

(p

ro

po

rti

on

of

max

imu

m)

Chapter 5



Figure 5–21 Differences in forage plant morphology from one species to the next change their response to grazing height(from Blaser 1986)*

10

8

4

6

2

Bluegrass

Orchardgrass

Tall fescue

Bermudagrass

Stolons

RhizomesRhizomes

Soillevel

Grazingheight

Heig

ht

of

can

ap

y, i

nch

es

* Bermudagrass and Kentucky bluegrass can withstand close grazing since they hold some leaf area close to the ground and have foodreserves stored in prostrate stems, rhizomes, or stolons. Orchardgrass and tall fescue have less leaf area after close grazing. They alsocontain most of their food reserves in the stem bases. If the stem bases are damaged, they are slow to recover.

Grasses whose growing points enter the grazing zonemust rely primarily on basal or rhizome buds to pro-duce new leaves. Grasses that typically send theirgrowing points on vegetative tillers into the grazingzone are called jointed (culmed) grasses. They haveelongating internodes along all their stems. The grow-ing point is pushed up into the grazing zone as eachinternode starting from the base of the plant elongates.A leaf arises at each node. If the growing point isremoved from the stem, a dormant bud initiatesgrowth along the stem, along stolons or rhizomes, orfrom the plant base.

These jointed grasses rely heavily on stored foodreserve for regrowth. They must have a recoveryperiod to produce new leaves and restore food re-serves before being defoliated again. Typical jointedgrasses used for pasture are barley, bermudagrass, bigbluestem, corn, Johnsongrass, oats, reed canarygrass,smooth bromegrass, sorghum, sudangrass, switch-grass, timothy, and wheat.

When forages are grazed close so that little to no leafarea remains, it may take a week or more for dormantgrowing points to initiate growth or active growingpoints to reactivate leaf growth, as shown in figure5–20(c). In this example it takes 24 days before plantsare growing at their maximum rate. Note the sche-matic of grasses in in this graph shows a thinned standthat is also low in stature. If forage plants are repeat-edly grazed closer than they ought to be, plant andstem counts dwindle. This leads to lower production,bare ground, and a chance for less desirable plants(weeds) to invade the pasture. This situation is notgood for either rotational or continuously stockedpastures.

Grazing height in relation to where the growing pointsare held on the plant is important as well. Legumesthat require regrowth from leaf axillary buds, such asbirdsfoot trefoil and sweetclover, need to be grazedhigher than those that initiate regrowth from crownbuds or stolon nodes, such as alfalfa and white clover.



Chapter 5

Table 5–3 Suggested residual grazing heights for major pasture forage species 1/ (from Ball, et al. 1991; Barnes, et al 1995;Blazer 1986; Chessmore 1979; Hayes 1966; Serotkin 1994)

Pasture type Continuously stocked, Rotationally stocked,average height of minimum height atpasture (in) removal (in)

Predominately grass

Bahiagrass 1.5 to 3 2Bahiagrass-legume 1 to 3 1Common bermudagrass 1.5 to 3 1Bermudagrass-white clover 1 to 3 1Hybrid bermudagrass 3 to 6 2Kentucky bluegrass 2 to 3 1 to 2K. bluegrass-white clover 2 to 3 1Bromegrass, smooth 2/ 4 to 5 2 to 3Orchardgrass 4 to 5 2 to 3Orchardgrass-Ladino clover 2 to 4 2Reed canarygrass 2/, 3/ —— 2 to 3 4/

Ryegrass 2 to 3 1 to 2Ryegrass-white or Ladino clover 1.5 to 3 1 to 2Switchgrass 3/ —— 6 to 8 4/

Tall fescue 4 to 5 2 to 3Tall fescue-Ladino clover 2.5 to 4 1.5Winter small grains 3 to 6 3

Predominately legume

Alfalfa 3/ —— 1 to 3 5/

Arrowleaf clover 2 to 4 2Berseem clover 3/ —— 3 to 4Birdsfoot trefoil, prostrate type 3/ —— 1 to 2Birdsfoot trefoil, upright type 3/ —— 2 to 3Crimson clover 2 to 4 2Ladino or white clover 1 to 4 2Lespedeza 3/ —— 3Red clover 3/ —— 2Rose clover 2 to 4 2Subterranean clover 1 to 3 1

1/ Heights given are those to maintain stand vigor and longevity. Greater heights may be needed to maintain proper intake for certain livestocktypes and classes.

2/ Must be grazed before jointing occurs or allowed to mature for hay and aftermath grazed.3/ Not recommended for continuous stocked pasture use; includes grazing type alfalfa.4/ Stubble height largely dictated by stiff stems discouraging lower defoliation.5/ Stubble height of 3 inches for overwinter protection. Grazing type benefits more from residual stubble height during the growing season than

does a hay type.

Chapter 5



Nonjointed (culmless) grasses maintain their growingpoints on vegetative tillers below or at ground levelmost of the year. They send up reproductive jointedstem stalks once per season. These grasses are resis-tant to close grazing and not very dependent on storedfood reserves except at green-up. This is mainly be-cause when grazed, their actively growing leavescontinue to elongate. The active meristematic tissue ispushing them up from below and creating fresh new

photosynthetic area. These grasses can be continu-ously grazed provided enough leaf area is left to pro-duce maximum photosynthetic activity. Typicalnonjointed pasture grasses are bahiagrass, bentgrass,Dallisgrass, Kentucky bluegrass, little bluestem,orchardgrass, redtop, ryegrass, and tall fescue. Figure5–22 is a visual comparison between jointed andnonjointed grasses.

Figure 5–22 Response of a nonjointed grass like Kentucky bluegrass compared to a jointed grass like switchgrass*(from Waller, et al. 1985)

��

��Elongated tillers

Unelongated tillers

Growingpoint level

Growing pointsremain

Regrowth

Growth point level

Growing pointsremoved

RegrowthBasal bud

* Same leaves continue to grow on bluegrass. Switchgrass starts tillers from basal buds. Older stems die.

Kentucky bluegrass

Switchgrass



Chapter 5

Shifts in plant species composition often occur unin-tentionally under different grazing regimes (fig. 5–23).In the 6 years of applying three different types ofstocking management to three sections of a pastureseeded to a uniform mixture of pasture forages, spe-cies composition shifts occurred swiftly. Figure 5–23starts with year two. The top graph shows the shift inpasture species where stocking was light, but continu-ous. Spot grazing occurred, leaving high stubbleheights in ungrazed areas. The taller upright grasseswere favored over Kentucky bluegrass. Canada blue-grass being less palatable proliferated. Timothy de-creased after an initial increase resulting from droughtin the fourth year. It reached an equilibrium point inyears five and six. White clover never gained anyground because stubble heights were too high forsunlight to reach it.

The middle graph in figure 5–23 shows the result ofheavy, continuous stocking. Grazed close, this pro-moted Kentucky bluegrass at nearly the expense ofeverything else. White clover was initially favored, butdecreased in the final two years because of the dryweather. Timothy almost disappeared from the standas a result of repeated drawdown of food reserves.Canada bluegrass recovery in the final year resultedfrom a weakened Kentucky bluegrass stand fromdrought.

The third graph in figure 5–23 shows the effect ofheavy grazing rotationally. Kentucky bluegrass andwhite clover were favored because the grazing heightwas close. Most taller grasses nearly vanished. Timo-thy was not grazed during stem elongation whileheading out. It was allowed to restore food reservesand remained fairly constant in ground cover. A lesspalatable grass, such as Canada bluegrass, is eatenwhere livestock are restricted to a smaller grazingunit. It appears from the rate of gain data in the pub-lished report (not shown) that they were not givenenough forage on-offer and were forced to eat every-thing provided.

Grazing height can also be used to intentionally ma-nipulate species composition in pastures. White cloverpersistence and percentage of the stand, for instance,are readily improved by grazing a pasture to a lowgrazing height. Under rotational stocking, this tempo-rarily removes the grass canopy grown in associationwith white clover and allows light to penetrate downto the stolons. This activates growth of new leaves

Figure 5–23 Changes in species composition over a 5-yearperiod under different stocking regimes(from Smith 1975)

Years

Percen

t o

f gro

un

d c

over

Years

Years

Percen

t o

f gro

un

d c

over

Percen

t o

f gro

un

d c

over

Redtop

Redtop

Redtop

Timothy

Timothy

Timothy

Kentuckybluegrass

Weeds

Weeds

Weeds

Whiteclover

White clover

White clover

Orchard-grass

Kentuckybluegrass

Kentuckybluegrass

Canadabluegrass

Canadabluegrass

Canadabluegrass

Orchardgrass

50

Light continuous

Heavy continuous

Heavy rotational

40

30

20

10

02 3 4 5 6

50

40

30

20

10

02 3 4 5 6

50

40

30

20

10

02 3 4 5 6

Orchard-grass

Chapter 5



from nodes (fig. 5–24). The white clover then is ableuse this light energy to produce food for continuedstolon growth and spreads laterally. Yet, if a tall grass,such as switchgrass, is the forage to be retained,maintaining high stubble heights and perhaps takingthe first growth off as hay shade out competing cool-season forages.

On humid northern pastures, cool-season grasses,such as bluegrass, are likely to invade warm-seasongrass pastures if stubble heights and plant densities ofthe warm-season grass are not kept high. In this casethe two grasses are incompatible and, over the longhaul,one will win out over the other depending on thegrazing height achieved. In the South where cool-season winter annual forage growth and warm-season

grass growth do not interfere with each other, it maymean only to graze the warm-season grass close at theend of its growth cycle in the fall. This promotes theonset of growth of an interseeded cool-season grass orlegume. The cool-season winter annual grass or le-gume normally dies back before or shortly after theonset of the warm-season grass growth the followingseason. An example of this is the combination ofbermudagrass and interseeded annual ryegrass orlegume, such as arrowleaf clover. A nearly continuoussupply of pasture year-around in the same field ispossible.

Figure 5–24 Differences in regrowth of white clover as result of grazing height; removal of the grass canopy favors thegrowth of white clover (from Blaser 1986)

Bluegrass White clover

Grazed to one inch Regrowth

Grazed to two inches Regrowth

Bluegrass White clover

1"

2"



Chapter 5

If the photosynthetic area is reduced below an LAI of 3or the apical growing point is removed because it iselevated into the grazing zone, a recovery period forthe forage crop is needed. This is often referred to byother authors as a rest period, which is a misnomer.The plant has undergone major surgery by the grazinganimal. It is not resting. It is recovering. Initially, it isusing stored food reserves to grow new leaf area. Itneeds time to restore enough leaf area to intercept asmuch sunlight as possible. It may also need time tobuild up the food reserves depleted in initiating dor-mant bud growth. If the surgery was too radical orfood reserves were too low, it may not have enoughactive meristematic tissue to recover. This can beparticularly true if other stress vectors, such asdrought, cold, disease, or insects, occur. When thishappens the plant population thins. Plants with fewactive meristems become shaded out by plants thathave more actively growing leaves and nondormantbuds.

Different forages have different recovery period re-quirements. Forages with widely fluctuating growthrates throughout their growing season need variablerecovery periods. They grow quickly at one time of theyear and very slowly at other times. Recovery periodsmay be as short as 10 days and as long as 60 days ormore. Pasture species falling into this category arebluegrass, reed canarygrass, orchardgrass, perennialryegrass, tall fescue, and white clover. To a largeextent, the return of livestock to the pasture is deter-mined by available forage target the operator is willingto accept (fig. 5–25).

Other pasture forages respond better to a fixed recov-ery period. The legumes in this group when faced withdry, hot weather will go to physiological maturityregardless of stature and vegetative growth will cease.Extending the recovery period only hurts quality andproduces no additional forage. The grasses, if grazedtoo late, go to physiological maturity, and many leavesare lost to senescence. This reduces the quality andquantity of forage ingested. If either of the legumes orgrasses of this group are grazed too early, food re-serves or leaf area are not restored sufficiently. Thiscan lead to a steady decline in plant, stem, or tillercounts. Pasture species in this category are bahia-grass, bermudagrass, big bluestem, Dallisgrass, alfalfa,red clover, smooth bromegrass, switchgrass, and

timothy. A generalized fixed time interval cannot begiven because it does vary by species and climate.Recovery times deemed sufficient for long-term foragesurvival are even debated for some species. Alfalfa, forinstance, was stated as being somewhere between 28to 35 days. With the newer pasture-type alfalfas, someagronomists recommend only a 21-day recovery pe-riod. However, this is based on leaving enough stubblewith leaves to carry on some photosynthesis.

Forage crops that are going into a winter dormancyperiod require a special recovery period near the endof their growing season. This allows them to developenough food reserves to make them cold hardy as wellas store energy for next year’s green-up period. Nor-mally, a 4- to 6-week recovery period is needed. Underrotational stocking, this can often be accommodatedin the regular rotation. Under continuous stocking,some way of reducing stocking density by opening upother grazing areas, such as fields with grazable cropresidue, or temporarily removing livestock from thepasture is helpful.

Figure 5–25 Variable recovery period* (from Murphy1988)

4000

2000

Avail

ab

le f

orage, lb

/ac (

20

% D

M)

0 5 10 15 20 25

0 10 20

Fast growth period in days

Slow growth period in days

30 40 50

Shorterrecoveryperiods

Optimumrecovery period

* During fast growth periods, days for recovery are half that ofslow recovery period in this example. During prolonged periodsof moisture stress, recovery periods can be much longer beforeavailable forage target is reached for class of livestock beingpastured. Note shorter recovery periods fail to make much use offast accumulation rate portion of growth curve (typical ofcontinuously over-stocked pasture).

Chapter 5



(c) Selective (spot) grazing ofpastures

As mentioned earlier, a characteristic of pasturesetting it apart from hayland and cropland is that it canbe harvested (grazed) unevenly. Several factors con-tribute to this. However, the primary factor that setsthis into motion is the forage supply exceeds livestockdemand, either seasonally or season long. Here again,this shows the importance of forage growth curves. Ifflush periods of growth are not accounted for, forageproduction gets ahead of the herd’s or flock’s ability toeat it. The animals tend to go back to previouslygrazed areas where the less mature (vegetative) plantsare because these forages are more palatable. Oncepatches of mature (reproductive tillers present) forageplants establish from grazing preference patterns, theypersist the whole grazing season, or possibly severalseasons, unless mowed (clipped). This can lead toseverely overgrazed spots and underutilized spots inthe same pasture. This does not occur on overstockedpastures nor on rotational pastures that have stockdensities in keeping with the amount of forage on-offer. In fact, on severely overgrazed pastures, zonesof repugnance (avoidance of livestock eating neartheir own waste) do not exist around urine and fecesspots. Even that does not contribute to selectivegrazing when animals are underfed. These pastures aregrazed uniformly closer than most lawn mowers cancut except for an occasional distinctly unpalatableplant. Forage utilization is high, but production is verylow.

(1) Factors involved in selective grazing

The main factors involved in selective grazing are:• Forage supply exceeds livestock demand• Plant palatability differences from species to

species• Plant palatability differences within species due

to maturity differences or level of anti-qualitychemicals

• Plant palatability differences due to terrain andsoil conditions

• Avoidance of plants soiled by dung and urine

Palatability differences among pasture speciesrevolve around two main factors: morphological andchemical. Morphological differences are differences inleaf coarseness and stem to leaf ratios. Chemicaldifferences are anti-quality metabolites that impart off-odors or flavors or that induce illness. Other factors,

such as succulence and fiber content, affect intake bylivestock using other grazing areas, but the differencesamong pasture species are relatively small.

Pasture species that are quite different in palatabilityshould not be planted together in a mixture. The leastdesirable species will be shunned. If they can spreadby seed or vegetatively, they will. Over time, they willincrease in areal extent. The more palatable specieswill be overgrazed and lost from the stand. This arguesagainst using shotgun seeding mixtures. It is hard toget more than two or three species together withoutgetting a significantly less palatable species added tothe mixture.

Some responses by livestock come from what

they are conditioned to eating. Often reedcanarygrass is avoided by livestock if they are notinitially raised on it. This can be for two reasons. Oneis that it has a large coarse leaf and with age becomesstemmy, a stiff stem at that. The other is that someecotypes are laced with an alkaloid that causes diges-tive problems in animals not conditioned to eating it. Ifit is grown in association with other grasses, it will beleft untouched and will eventually cover the grazingunit. If it is rhizomatous and tall, it spreads and shadeseverything else out.

Tall fescue is similarly rejected if grown in associationwith other grasses. It tends to have leaves that arecoarser and tougher than other species. It also has analkaloid in it caused by the endophytic fungus,Acremonium coenophialum. This is toxic to animalscausing a number of symptoms: fescue foot, bovine fatnecrosis, and fescue toxicosis. The first two condi-tions can be worsened by high nitrogen fertilizer ratesfrom commercial fertilizer or manures, such aschicken litter.

Within species selective grazing is most oftencaused by succulence differences. As the plants ma-ture, they become less succulent and more fibrous.Mature seedheads also make the areas less inviting tograzing. Areas that are initially grazed are repeatedlyregrazed when animals have the chance to graze moreforage on-offer than they can eat completely. Theforages in these areas are younger and therefore moresucculent. If given a wide latitude, livestock are veryselective.



Chapter 5

Chemical differences are less important except whereendophyte infested tall fescue pastures are renovatedand planted to endophyte-free tall fescue. In this casethe chances of having a few infected plants survive orgerminate from the soil seed bank are quite high. Withtime these plants may capture more and more groundarea as they are rejected and allowed to proliferateover the more palatable and less hardy endophyte-freefescue. The alkaloids that are produced in response tothe endophyte make those plants bitter and causedigestive and metabolic problems in livestock.

Terrain and soil differences can cause spot grazingto occur. Shallow, low fertility, and low water holdingcapacity soils often produce more succulent plantsthan deep, high water holding capacity soils. Thesepoorer soils produce plants with finer leaves, moreleaves, and higher sugar content than plants on thebetter soils. Because these sites are more fragile tobegin with, their attractiveness as food fare onlyworsens their ecological condition. They will be thefirst site to show the effects of overgrazing even ifother areas of the pasture are not. These areas oftenoccur on knolls and ridge points that have south andwest aspects. Often low, poorly drained sites are saidto produce washy plants. These plants have coarserleaves, lower sugar content, and become stemmyquickly. Consequently, livestock reject the forage inthese areas or use them only as a last resort.

Steep sloped areas will be avoided or underused bylivestock if more level terrain is available with ad-equate forage reserves. This is particularly so in moun-tainous terrain where distance to water may also begreat. Limited water sources tend to cause areas ofpasture nearest the water to be overgrazed while areasfarther away are underutilized if used at all. Bare areasmay encircle the water source, and trailing to and fromthe water source may become excessive. If the patternis allowed to occur for several years, ecological suc-cession can begin to progress in areas remote to thewater source. Woody vegetation can invade makingthe fringe pasture areas from the water source becomeeven less desirable to graze.

Shady areas that exist along fencelines or in thepasture itself often influence grazing patterns as well.These areas cause a grazing pattern similar to thataround water sources. Close grazing occurs nearshady areas, and utilization decreases with distanceoutward. Because of heavy treading pressure undertrees, vegetation may often be lost entirely in theshaded area.

Barriers, such as fencelines, rock outcrops, cliffs, andhigh walled streams, often disrupt grazing access. Theareas made difficult to reach are so infrequentlygrazed that they become overmature. Once they reachmaturity, they are less desirable and perpetuate theirstatus as a little used foraging area. If cattle find themhard to get to, these areas will be left unmanaged bythe land unit manager. They may eventually revert towoody vegetation.

The remaining effect causing selective grazing is theavoidance of grazing near dung or urine spots.

This is less of a problem with sheep and horses than itis with cows. Cattle may reject forage in an areasurrounding the dung pat 5 to 12 times the size of thepat. Depending on the controls of forage on-offer andforage species being grazed, the amount of pasturearea rejected may be none under an overstockedscenario to as high as 70 percent found in a studyconducted on a continuously grazed coastalbermudagrass site after 98 days of grazing.

Commonly, 20 percent of the available forage can bewasted because cattle avoid dung spots. Fresh urinespots are avoided. Older urine spots, on the otherhand, may attract grazers especially during driermonths. The grasses there tend to be more succulentbecause of the effect of high soil nitrogen concentra-tions on the growth of the grass. Plants with adequateto excessive levels of nitrogen remain greener longerunder drought stress than other plants in the pasturehaving less nitrogen available to them.

Chapter 5



600.0505 Conservationpractices for pasture

(a) Harvest management practice—Prescribed grazing

The prescribed grazing conservation practice is usedto provide adequate nutrition to animals while main-taining or achieving the desired vegetative communityon the grazed site. The principal agent for vegetativemanipulation is the grazing animal. If the controlledstocking of grazing animals cannot effectively changethe vegetation toward the desired level of productionor forage species composition in the time frame de-sired, then accelerating conservation practices areemployed. These practices are described later indetail.

(1) Principles of allocating forage to live-

stock—pasture budgeting

The two main goals of the prescribed grazing practiceon pasture are:

• To achieve acceptable livestock production oneither a per land unit basis or per animal basis.

• To maintain a healthy forage base on the pastureacres.

The decision to do either one or a combination of thetwo is up to the landowner or operator. Circumstancesdictate which one of these is most desirable or ifstriking a balance between the two is best.

(i) Achieve acceptable livestock production—

Seedstock producers stake their reputation on provid-ing superior performing animals. Therefore, it is ap-propriate that they seek maximum performance peranimal.

Commercial operators, on the other hand, may wish tooptimize production on a per acre basis. This is par-ticularly important where land prices and propertytaxes are high. High costs of land ownership or rentingdictate being efficient on a per acre basis. However,these same commercial operators may not want tolose too much animal performance if it means asmaller net profit, or deferred sales resulting fromslower gains on meat animals. The latter means pos-sible cash flow problems, increased interest costs, and

foregoing the time value of money. These operatorsmay want to strike a balance between output per headand output per acre.

NRCS needs to work with landowners and managersto avoid the extremes shown in figure 5–26, especiallythe overstocked situation. In the overstocked situa-tion, forage production declines because of overhar-vest. There is an increase in grazing pressure eventhough animal units may stay constant. There is justless forage growing to be eaten. As a result, in highlyoverstocked cases there may be actually a loss inweight by the grazing animal because their mainte-nance needs are not being met. In these cases all fivenatural resources (soil, water, air, plant, and animal)are in jeopardy. Plants are lost. As a result, animalshave too little to eat. The soil with too little covererodes by wind, water, or both. This in turn impactsair and water quality.

On the other end of the graph, the pasture may beunderstocked. There is more forage than the livestockare able to consume. This leads to spot grazing. Theanimals do well individually because they return tograze previously grazed material that is younger andhigher in quality. However, the number of animals islow in relation to the potential forage available. Pro-duction of animal products per acre suffers. Over time,pasture quality and production decline if far in excessof livestock needs. Much of the forage production will

Figure 5–26 Relationship of output per head versusoutput per acre based on grazing pressure(animal units per # DM) or its reciprocal,forage allowance (# DM per animal unit)(adapted from Barnes, et al. 1995)

High

Med

Low

Neg. Low Med High Very high

High Med Low Very low

Output/headOutput/acre

OvergrazedUndergrazed Optimumrange

Forage allowance

Grazing pressure

Pro

du

cti

on



Chapter 5

senesce. This senesced residue shades the ground andcauses plant thinning unless the pasture is clippedrepeatedly.

Going from a high forage allowance to a lower forageavailability status is possible without increasing live-stock numbers. As forage plant numbers decline, a lessvigorous sod allows weeds and woody vegetation toinvade. With low livestock numbers, these plantssurvive and eventually dominate areas of the pasture.This can impact the five natural resources as well. Thebiggest impact is felt by the plant and animal re-sources. The plant community transitions into some-thing less desirable as a forage resource. Browsersmay be favored over grazers if succession back to-wards forest occurs. In advanced stages, areas ofovergrazing will co-exist with undergrazed.

Both situations can be reversed back toward themiddle of the graph. There the forage allowance givenper animal unit is somewhat short of maximum rate ofgain per head, but allows for a higher utilization rate ofthe forage and a much higher output per acre. There-fore, it is critical to know first what the forage require-ment is per animal unit. General rules of thumb havebeen 2.6 percent of body weight for most ruminantsand 3.0 percent of body weight for lactating dairycows. However, these should not be considered abso-lutes.

Intake is affected by forage quality, temperature,amount of forage on-offer, and animal condition. Anormal range of values is 1.5 to 4 percent of bodyweight. The optimum forage allowance is this requiredforage ration plus some additional forage mass tocover losses by rejection, trampling, and soiling aswell as to make it easy for animals to get a full biteeach time. This optimum is expressed where theoutput per head and output per acre lines cross infigure 5–26. If the actual forage allowance deviatesfrom this optimum, the results are shown in figure 5–26 and were described earlier. If stored feed is fed inaddition to pasture forage, this dry matter contributionshould be subtracted from the ration.

(ii) Maintain healthy forage base—The secondmain goal of prescribed grazing is maintaining ahealthy forage base on the pasture acres. Forages are arenewable resource when harvested with their needsin mind. This means stocking livestock commensuratewith the amount of available forage throughout the

grazing season. When overgrazed or undergrazed,forage stands continue to renew themselves, but atlower and lower levels of production. Over time, thestand thins in plant and stem numbers. Invasion byless desirable plants occurs.

For those forages tolerant of continuous grazing andmanaged that way, it means leaving enough residualstubble height to maintain optimal leaf area for fullsunlight interception while guarding against under-utilized areas caused by spot grazing. Perennial foragepastures may need to be clipped (mowed) when areasof mature plants produce seedheads. This stimulatesthose plants to produce new vegetative growth.

For those forages better suited to rotational stockingmethods, it means leaving enough residual stubbleheight to allow recovery of the plants. It also meansrespecting the recovery period needed by these for-ages. Delaying or speeding up stocking schedules cando harm to the forage stand as well as cause distor-tions in feed quality and quantity. Delays can developbecause of faster forage growth than expected or thegrazing period is extended to use pasture subunits orpaddocks better. When this occurs some of the pad-docks nearing seedhead emergence or bud floweringshould be cut for stored feed unless they can be stock-piled for grazing later. If return interval starts to speedup as a result of grazing periods being cut short forlack of enough available forage, supplement pasturewith stored feed or, if available, bring in additionalgrazable acres.

Paddock forage growth should be measured well inadvance of the herd. All paddocks should be moni-tored once per week. If measured and charted, the rateof growth for each paddock can be determined. Con-sidering the rate of growth and any trends observed(declining, flat or rising growth rate), the operator canproject when each paddock will be ready to grazebased on available forage target. If the projectionshows available forage target is exceeded well beforelivestock will occupy a paddock and several paddockswill be in this condition, either adjust stocking ratesupward or machine harvest the number of paddocksrequired to get to a paddock that meets availableforage target. If some paddocks are slower to recoverwhile others are faster, the operator should adjust thesequence of paddock grazing to accommodate thevariance in growth rate. These differences are causedby forage species composition, soil type, aspect, or

Chapter 5



grazing residual height variability associated with thesite and season.

Available forage is a critical term needed regardlessof grazing method. As applied to pasture, it should bedefined as the consumable forage in pounds of digest-ible dry matter per acre between the allowable mini-mum stubble height for the preferred forage speciesbeing grazed and the plant height achieved before orduring grazing. It should not be to the height to whichthe grazing animal can graze it down. This fails torecognize the harm done to the forage crop whengrazed too close, the resource that the animal andproducer depend upon for their livelihood. It may beavailable to the animal, but it is not indiscriminatelyavailable if forage persistence and vigor are desired.As it was defined here, it is sometimes called usableforage.

Another key to the definition is that available forage isconstantly changing unless forage is dormant or dead.

Available forage is changing before grazing. It in-creases as the forage grows ungrazed. Available foragedeclines once grazing is initiated in rotational grazingmethods. It declines until the animals are removed. Itfluctuates up or down under continuous grazing meth-ods depending on how finely tuned grazing pressure isapplied and the variability in forage growth rates inrelation to livestock stocking rates (animal units peracre). The importance of this moving target is that itmust meet each class of livestock's requirements at alltimes.

Figure 5–27 shows the relative amount of availableforage that must be presented to different kinds andclasses of livestock. Otherwise, a loss in livestockproduction occurs when it falls below the minimumrequired. If rationed too tightly, the animals are notable to maintain intake. In some instances, someclasses of livestock, such as milk cows, have a fall-offin production before grazing to the minimum stubbleheight needed to maintain plant vigor. High producing

Figure 5–27 Available forage requirements for different classes and ages of livestock (from Blaser 1986)

Very low

Very low

Low

Medium

Rela

tive d

ail

y d

igesti

ve d

ry m

att

er i

nta

ke

Available forage

High

Low Medium High

Fattening cattl

eCalves, lambs,

coltsand fill

iesMilk

cows

Herdre

placements

Ewesand bee

f cows

Mares



Chapter 5

milk cows simply need more available forage or a highforage allowance to maintain a high level of intake.They need to move to pastures that have sufficientavailable forage or be fed stored feed. Dry matterintake by high producing milk cows falls off rapidly asavailable forage declines below 1,000 pounds per acre.Other classes that only need to maintain body weightmay graze below the minimum stubble height neededfor the health of the preferred forage community if laxgrazing management is applied. Where too muchavailable forage is presented, spot grazing can occurand animals may be overconditioned (too fat). Thelatter can lead to livestock reproductive and healthproblems too and waste a valuable forage resource.Methods for monitoring available forage are describedin chapter 5.

The other key to the definition of available forage isthe term, digestible dry matter. This accounts notonly for the quantity of forage available for consump-tion, but its quality as well. As stated earlier, pastureforage kept in a vegetative state has a higher digestibledry matter content than it does typically when har-vested as stored forage. Much of this is related to itsstage of maturity, but it is also a reflection of lossessuffered by stored roughage during harvest operationsand storage. Pasture forage should therefore be allo-cated based on its quality as well as quantity, or utiliza-tion will be less than predicted. A forage allowancebased only on total dry matter will be too generous onhigh quality pastures.

Pastures that run above 65 percent digestible drymatter dampen dry matter intake for many classes oflivestock depending upon their energy requirements.For example, see figure 5–28. This illustration depictsdry matter intake versus dry matter digestibility fordairy cows at different milk production levels. Theintake of a low producing milk cow drops off startingat 56 percent digestible dry matter. While that of a highproducing cow does not drop off until forage digest-ible dry matter exceeds 75 percent. High producersonly get this much digestible dry matter by being fedconcentrates along with pasture forage. Pasture foragemay be 75 to 80 percent water and will fill the gutbefore the percent digestible dry matter factor caninfluence intake.

Forage utilization is the percent of available forageactually consumed by the grazing animal based on netforage accumulation that occurs before and while they

occupy the pasture unit. The amount of availableforage presented times the acreage of the pasture unit(forage on-offer) must equal the forage allowancerequired to feed the herd or flock for the period theywill occupy the pasture unit unless supplemental feedis fed. In other words, if 15 animals were to occupy a1-acre pasture unit for 3 days and had a forage require-ment of 25 pounds of digestible dry matter per animalunit per day, 1,500 pounds of available forage wouldbe needed on that acre if the utilization rate was 75percent (1,500 lb/ac x 0.75 x 1 acre = 1,125 lb = 25 lb/au/day x 3 days x 15 au).

A 100 percent efficient enterprise is impossible with-out unacceptable livestock performance. As livestockmove about grazing, some forage is rejected, sometrampled, and other soiled as the animals selectivelygraze the choicest plants and plant parts first. Thelarger the area and more days on the pasture, the moreforage lost to initial rejection, trampling, and soiling.

Table 5–4 gives utilization rates versus grazing periodlength. The table values should be viewed as estimatesonly. The upper limit on high quality rotational pasturebefore intake by meat livestock becomes depressedenough to reduce gain per acre is 80 percent utiliza-tion. Forty percent utilization of available foragewould maximize forage intake, but leave muchunutilized forage behind (fig. 5–29). If the 80 percent

Figure 5–28 Dry matter intake of dairy cows based on drymatter digestibility and daily milk production(from National Research Council 1989)

��

66

55

44

33

22

11

00 50 55 60 65 70 75 80

Dry m

att

er i

nta

ke (

lb/d

ay)

Dry matter digestibility (%)

1320 lb cow4.0% fat milk

��

��

��

�

��

��

��

��

�

22 lb milk

44 lb milk

66 lb milk

88 lb milk/day

Chapter 5



ceiling is surpassed, then animal production per acredeclines quickly. At the same time some forage areaswithin the pasture unit will be grazed to stubbleheights lower than ideal for persistence and vigor. If 40percent or less of the available forage is used, indi-vidual animal performance is high, but the pasture isundergrazed.

Forage availability or allowance must be high for highperformance livestock for them to maximize intakerates that sustain high rates of gain or milk production.Intake declines as soon as dry matter per bite goesdown and the number of bites per grazing period goesup. The livestock classes shown at the upper end ofthe curve in figure 5–27 may need to be followed onrotational pastures with a less demanding herd oflivestock. For instance, the milking herd on a dairyfarm can be followed by dry cows and replacementheifers. On other farms calves, lambs, and colts maybe allowed to forward creep graze ahead of theirmothers. Their mothers once past peak lactation havea lesser intake requirement. This increases the overallutilization rate for the good of the forage stand and theefficiency of the pasture system.

To summarize, livestock must be given a forage allow-ance (pounds of dry matter per animal unit) thatcovers their forage requirement plus some wastage.

The practical limit is 20 percent wastage (80 percentutilization) before intake suffers in a big way andanimal production per acre starts to decline. Individualanimal performance has already declined at this point.At the 40 percent utilization rate, individual animalperformance has peaked, but available forage utiliza-tion is low.

To get the right forage allowance in front of the animalrequires a few critical items that are all interrelatedand form the basis of a pasture budget. These itemsinclude:

• How much forage in pounds of digestible drymatter (DDM) per acre is available?

• The number, kind, and class of animal units to beplaced on the pasture.

• Will these animals be fed stored feed while onpasture? If so, how much? This establishes theirtrue requirement for pasture forage.

• Establish length of stay in the pasture unit. Thisdetermines the final available forage amountbased on its status at the start of the grazingperiod and the growth rate during the grazingperiod. It also establishes the grazing periodforage requirement for the animal units beingpastured, daily forage requirement per animalunit times animal units times number of days ofgrazing period.

Table 5–4 Rotational pasture estimated utilization rates(from Penn State University, AgronomyGuide 1994)

Grazing period Pasture utilization(days) (%)

0.5 – 1 80

2 75

3 75

4 70

5 65

6 – 30 60

Figure 5–29 Forage utilization as it affects forage intake*(adapted from Hodgson 1990)

50

0 2.6 5 10

80

100

50

Uti

lizati

on

(%

avail

ab

le f

orage)

Fo

rage i

nta

ke (

% o

f m

ax

imu

m)

80

40

0

100

Forage allowance (% of live weight)

Utilization

Intake

* Available forage can be far in excess of that really needed tosatisfy herd appetite if stocking rate is low. Animals can readilyget all they can eat, but forage is wasted.



Chapter 5

• Estimate a utilization percentage. This is theleast precise input, but the practical range isbetween 40 and 80 percent.

This information helps in determining the forageallowance needed for the whole herd, grazing periodforage requirement divided by utilization ratio (step 6).The size of the pasture unit can then be determinedt(step 7) by taking the grazing period forage allowancefor the herd and dividing it by available forage duringthe grazing period (lb DDM / lb DDM/acre = acres).This is pasture forage budgeting. The process issimple. Gathering reliable data is the hard part. Notethat stocking rate, the number of animal units per acreper specified time period, was never relevant. It is anoutcome of the process once livestock demand andforage supply issues have been resolved. It becomesrelevant when animals are stocked with little regard tosupply-demand issues.

For pastures that have forages with widely fluctuatingseasonal growth rates and long grazing periods, suchas with season-long continuous stocking, calculatemonthly forage production during the high and the lowforage growth rate month. This determines the numberof animals that can be supported or the number ofacres of pasture needed during those two disparatetime periods in forage growth. This must be done forrotational stocking as well to determine differences intotal pasture acreage needed at these two differentperiods in forage availability. If more than one foragecommunity is pastured or pastures vary markedly intheir productivity, then these same calculations needto be done for each pasture being used.

Herd requirements for forage change with time aswell. They gain weight. Some are sold. Milk productionduring the lactation cycle for dairy cows fluctuatesgreatly and therefore so does their need for energy.This is especially important in figuring demand forseasonal dairying herds where all the cows are in thesame part of the lactation cycle. Therefore, as simpleas the forage budget process is, it is necessary toreiterate it as often as needed depending on the com-plexity of the pasture system being planned and used.

Care must be taken in developing forage budgets.Some budgets ignore forage quality. Others ignoreutilization, and some overcompensate for it. Otherbudget formats ignore both quality and utilization. Onhigh quality pasture this creates compensating errors,and the end result is a remarkably good answer formiddle of the road performing livestock. The drymatter forage requirement, 2.5 to 2.6 percent of bodyweight, assumes a level of digestibility considerablylower than that available from high quality pasture.Because this assumed digestibility is 70 to 80 percentof that available on high quality pasture, the foragerequirement already has the forage allowance coveredif the utilization rate is in the 70 to 80 percent range.

In figure 5–29 see the forage allowance required at the80 percent utilization rate. It equals 2.6 percent ofbody weight, but it assumed only 80 percent utilizationof that 2.6 percent of body weight forage allowance.Only 2.1 percent of body weight was actually con-sumed, and intake was only 80 percent of maximum.Remember this maximizes production per acre andsacrifices some animal performance. The margin israzor thin. After that, animal intake drops precipi-tously. The curve has to go to zero intake in a narrowrange of forage allowance. In other situations, such aslow quality forage or maintaining a high availability forhigh performance livestock, less detailed forage bud-gets would not work out so well.

(2) Stocking methods

(i) Allocation stocking methods—The four basicallocation stocking methods used throughout thecountry are continuous set stocking, continuousvariable stocking, set rotational stocking, and variablerotational stocking. Herbivores graze, but livestockproducers stock them on pasture. Hence, the use ofthe term stocking is preferred over the term grazing.Within the four basic methods, applications can varybased on livestock responses desired, climatic consid-erations, soil and terrain conditions, forage cropsbeing grazed, and management preferences of theproducer. The scope of this section is not to cover allthe various applications, but it will cover the morecommon ones. Figure 5–30 is a diagrammatic illustra-tion of each.

Chapter 5



Figure 5–30 Three classes of stocking methods and their associated stocking method* (adapted from Barnes, et al. 1995;Hodgson 1990)

Grazed off Last grazers

Offspring

Special forage

(Base pasture)

Mothers/Offspring

Offspring

First grazers

Front fence

DeferredDeferred

Spring

Winter Fall

Summer

Front fence

Back fence

Annual orperennialcool season

Annual orperennialwarm season

Stockpiledforage and/orwinter annual

Stockpiledor annualcool season

Animals access total area.

First-last grazing

Continuous set stocking Continuous variable stocking Set rotational stocking Variable rotational stocking

High performers graze first andlow performers graze last.

Offspring graze ahead of mothers,using special creep openings.

Mothers stay on base pastures,offspring creep graze special forage.

Flexible areas offered each day(with back fence).

Flexible areas offered each day(without back fence).

Forward creep grazing

Strip grazing Frontal grazing

Sequence stocking Deferred stocking

Continuous stocking-creep grazing

Area accessed by animalsexpands or contracts asforage supply dictates.

Example: 6 day grazing period and30 day recovery period. Example: Grazed 8%;

Recovering 92%.

Seasonal stocking methods

Nutritional optimization stocking methods

Allocation stocking methods

* Each method is diagrammed to show how the livestock are deployed about the pastures.



Chapter 5

Continuous set stocking method—Continuous setstocking of livestock either season-long or year-long isa common method of pasturing them. Continuous setstocking means the same numbers of animals are onone pasture unit for the whole grazing period. This is amisnomer because although the animal numbersremain constant, animal unit demand for forage oftendoes not. Meat animals gaining weight, and lactatinganimals have variable forage demands during thegrazing period. If set stocking is to be used, an averageforage allowance for the grazing period must be calcu-lated. If there is a recovery period, it is at the begin-ning or end of the grazing period (= season). If theforage being grazed has a very nonuniform distributionof growth, forage utilization will be low. Periods willoccur when forage growth gets ahead of livestock andtimes when it is too slow. During slow growth periods,livestock are forced to consume less palatable andlower quality forage that has collected in ungrazed orless grazed areas of the field. This reduces intake andalso lowers utilization. Low utilization at the beginningof the year perpetuates low utilization. First there istoo much to eat. Some forage matures. When theseason progresses, there is more low quality, high fiberforage than succulent. This reduces intake. Spotgrazing is high under this circumstance.

This method is appropriate, however, where bothforage growth and animal unit demand are relativelyevenly matched throughout the grazing period. An-other situation where it can work well is where theforage has made all or most of its growth and it will begrazed until it is gone. This works well on seasonalannual forages and on stockpiled forages. Regrowth isgenerally of little or no concern. With stockpiledperennial forages, a minimum stubble height should beobserved to allow it to go through its dormant periodwithout stand loss. For annual forages leave enoughstubble to protect the soil from erosion and allow onesthat can naturally reseed themselves time to produceseed, as needed, to get a good stand next season.

This stocking method has been equated with poorgrazing management. The method itself is appropriateunder the right forage growth circumstances and whenmanaged to provide the proper forage allowance to theclass of livestock being fed. Unfortunately, thismethod is applied all too often with none of that inmind.

Continuous variable stocking method—Continuousvariable stocking is a stocking method alternative thatadjusts land area or livestock numbers as forageavailability changes throughout the grazing period. Oncommercial operations, this method starts out with acore pasture that is grazed during the high growth rateperiod of the forage. As forage growth rate declines,this method attempts to add more acreage and avail-able forage to the livestock ration. The additionalacreage is often harvested for stored roughage first. Itis allowed to regrow. Then, it is opened up to livestockgrazing as the core pasture forage growth rate starts tofall behind the livestock removal rate, or the availableforage is nearing the desired maximum percent utiliza-tion rate. The decision to open up additional pasture isbased on forage stubble height, changes in spot graz-ing behavior, animal performance, or a combination ofthese. With a milking herd, when milk production tailsoff and can be correlated to pasture condition, thissignals a need to increase forage intake by increasingpasture size. The other alternative for this method is tokeep the pasture the same size and vary livestocknumbers. This is done in an experimental plot setting,but is not common on commercial operations. Theprocedure is called put and take. Livestock numbersare varied as forage growth conditions warrant.

Some pasture forages are not well adapted to continu-ous grazing. They are alfalfa, big bluestem,Indiangrass, Johnsongrass, red clover, sericea lespe-deza, smooth bromegrass, switchgrass, and timothy.Many of these forages disappear completely undercontinuous grazing while the others persist, but at lowlevels of production. If managed under a rotationalsystem, some forages respond and increase in percent-age of total forage production and ground cover.These forages depend on a cycle that allows them torebuild food reserves while they reach physiologicalmaturity. Continuous grazing never allows that tooccur.

Other forages, such as birdsfoot trefoil, Coastalbermudagrass, orchardgrass, perennial peanut, and tallfescue, are adapted to continuous grazing as long asthey are not grazed too closely. If grazed close, theywill persist, but in fewer plant numbers and at a muchreduced growth rate. Bahiagrass, commonbermudagrass, Dallisgrass, Kentucky bluegrass,ryegrass, white clover, and many annual clovers areadapted to close continuous grazing. They hold muchof their leaf area and their growing points below the

Chapter 5



grazing zone. Bahiagrass and common bermudagrassoften increase when present in a mixed stand withCoastal bermudagrass.

Set rotational stocking method—Set rotational stock-ing is a stocking method that falls under several differ-ent names depending on what region of the country itis used in. This method is useful on pastures whereforage growth rates vary little or physiological matu-rity is going to occur regardless of forage height andgrowth rate. These forage crops respond to a recoveryperiod because they need time to build food reserveswhile gaining in leaf area.

This general method has a set grazing cycle period. Aset grazing period and a set recovery period make acomplete set time cycle before the livestock return tothe same pasture paddock or subunit. It is obviousfrom table 5–4 that higher utilization rates occur if thegrazing period is short. It is rather important to mostpasture forage species with elevated growing pointsthat the grazing period not extend beyond a week.Otherwise, regrowth begins that may be grazed offwhen livestock are stocked at high densities. This candrawdown food reserves and make recovery slow asmore growing points must break dormancy and growto replace the newly initiated, but grazed off points.The recovery period is set based on the recoveryperiod needed by the forage crop. The recovery periodtime and the grazing period time determine the num-ber of paddocks needed. The recovery period timedivided by the grazing period time plus one equals thenumber of paddocks required. For instance, alfalfamay require from 21 to 28 days to recover dependingon the cultivar being grazed, pasture-type versus hay-type, and growing degree days for the region. If apasture-type is grazed for 1 day and recovers for 21days, 22 paddocks are needed. If the grazing period isextended to 7 days, only 4 (21/7 + 1), but much larger,pasture subunits are required.

A weakness in the set rotational stocking method isthe variability that can occur with available forage in apasture subunit from one cycle to the next. If it truly isset, it cannot account for changes in forage growthrates well. Alfalfa, for instance, will go to physiologicalmaturity under drought conditions and flower eventhough it may be several inches shorter than it waswhen water was plentiful. A paddock that was sizedright for optimal moisture conditions is going to be toosmall under drought conditions. Some fine tuning of

paddock size may be warranted. This can be done withportable fences. Another option is to oversize pad-docks to strike a balance between projected highs andlows in production. The other option is allow someflexibility in the grazing period seasonally and incorpo-rate another field during low forage accumulationperiods. Keep paddocks the same size, but reduceoccupancy time to match available forage with forageallowance needed for the herd. Recovery periodsremain set, but now more paddocks are grazed duringthe recovery period than when forage growth rateswere high.

Pasture forage crops that respond best to a set grazingcycle period are alfalfa, big bluestem, birdsfoot trefoil(upright), Coastal bermudagrass, indiangrass,Johnsongrass, perennial peanut, red clover, smoothbromegrass, switchgrass, and timothy.

Variable rotational stocking method—Variable rota-tional stocking is a stocking method that adjusts therecovery period to the variable growth rate of foragespecies being grazed. The grazing period is generallyset. In practice, it often is not. If the grazing period isnot set, it tends to only defer problems of too much ortoo little forage within the area set aside for rotationalpasture. The grazing period for high performanceanimals (intensive or short duration rotational stock-ing), such as lactating dairy cows, fattening cattle, andyoungstock, should be no longer than 3 days, prefer-ably not more than 1 day. For other livestock classesthe grazing period can extend up to 7 days, but prefer-ably not more than 4 days to prevent grazing of newleaf growth.

If a first-last stocking method is used, the combinedtotal period of occupancy should not exceed 7 days (3days for intensive rotational stocking). The grazingperiod length must be determined by animal perfor-mance, forage availability, and target residual stubbleheight or mass of forage to get rapid regrowth duringthe recovery period. This is initially determined usingthe pasture budgeting technique described earlier. Ifone or more of the estimates used to determine pad-dock size is off, the decision to deviate from theplanned grazing period must be based on availableforage and stubble height left at time of viewing.



Chapter 5

This method is similar to the continuous variablestocking method in one respect. It relies upon expand-ing or contracting the area being actively grazed dur-ing the grazing season. During periods of high foragegrowth rates, the number of paddocks and pasturearea is least. During periods of slow or arrested foragegrowth, the number of paddocks and pasture areaexpand to provide an adequate forage allowance forthe herd in each paddock throughout the grazing cycleperiod. This additional pasture acreage typically ismachine harvested until needed for grazing use. Graz-ing is initiated when enough forage has accumulated ineach paddock to meet the herd’s forage allowance(available forage x area x utilization rate = livestockdemand).

This rotational system can have a high degree offlexibility. Paddocks can be stocked out of sequencewhen forage growth is variable from paddock topaddock because of landscape position, differing soilfertility and water holding capacity status, foragespecies composition differences, or past grazingpressure. When forage supply is much higher thanexpected, fewer paddocks than usual are stocked pergrazing cycle and more are machine harvested. If theforage supply is low, additional paddocks are broughtinto the grazing cycle. In severe shortages the machineharvested forage made earlier when forage was inexcess of livestock demand is available for feeding.This becomes critical if pasturing must cease to pre-vent forage stand loss or prolonged delay in foragerecovery after the stress period has passed. Recoveryperiods range considerably, from 10 days to more than60 days.

Pasture forages that respond best to this stockingmethod are ball clover, bentgrass, berseem clover,birdsfoot trefoil (prostrate), Kentucky bluegrass,orchardgrass, perennial ryegrass, redtop, reedcanarygrass, tall fescue, and white clover.

(ii) Nutrition optimization stocking methods—

These stocking methods are used to selectively feedlivestock. They can be associated with either continu-ous or rotational stocking methods. They are first-

last grazing and strip grazing. Creep grazing, whereyoung stock graze ahead of their mothers, is generallyconsidered a separate category, but in effect is just aform of first-last grazing on rotational pastures. Onrotational pasture, it is called forward creep grazing.

On continuous pasture, creep grazing requires a sepa-rate pasture of high quality forage which the mothersmay never gain access to. Therefore, it becomes itsown separate category in that situation. Strip grazingalso has a variation to it called frontal grazing. Stripgrazing requires a back fence to keep livestock off thepreviously grazed area. Frontal grazing providesanimals with a fresh strip of forage too, but has noback fence. Animals have access to the land previouslygrazed as well as the new forage being offered. Bothmajor selective methods and their variations areenhanced attempts of offering the appropriate plane ofnutrition to the classes of livestock being pastured.

Creep grazing—Creep grazing allows young stock tograze forage their mothers cannot get to. It is usedwith meat type animals to get higher weaning weights.In either continuous pasture setting or rotationalpasture, a gate with an opening just large enough toallow young stock to pass through is placed in thefence between the shared pasture area and the creeppasture. On rotational pastures, the mothers follow theyoung stock onto the forward paddock after the youngstock have had first choice of the available forage. Inthis instance, it is a first-last grazing method. On con-tinuous pasture the young stock have access to aseparate field of high quality forage. The mothers mayonly get to clean it up near the end of the growingseason or never gain access to it. In lieu of creepgrazing, creep feeders may be placed in pastures sothat only the young stock have access to high energyfeeds for faster weight gains.

Another common first-last grazing scenario placeslactating dairy cows ahead of heifers and dry cows onrotational pasture. High production lactating dairycows require a high forage allowance to keep intakefrom falling off near the end of the grazing period thatthey are in a paddock. After they are removed, consid-erable available forage is still left. Heifers and drycows having lower intake requirement can use forageleft behind by the milkers.

Other first-last grazing combinations are rapidly grow-ing weaned youngstock being placed ahead of thebrood stock. Because high daily gains are desired ofthe meat animal, they are removed before intake startsto fall off and the quality of forage ingested declines.Care must be exercised to keep the total occupancyperiod no longer than 6 to 7 days on rotational pasturewhen grazing forages with regrowth potential.

Chapter 5



Strip grazing—Strip grazing in its ultimate usage istrying to maximize utilization of standing forage bylimiting the amount of fresh forage at any one time tothe grazing herd. This tends to increase intake becausethe herd responds to fresh forage on-offer by grazingas soon as it becomes available to them. If intakeincreases, this will increase milk flow or weight gain.Thus, it is best utilized with high performance live-stock. Generally it occurs on fields that are also ma-chine harvested. The interior fences subdividing thefield are portable and are removed once the field isreadied for machine harvest again. Thus, no barriersare present to impede equipment traffic. Strip grazingmay break forage allocation down to units smallenough to be grazed off in one to four hours. Theforward and back fences are picked up and moved tonew positions based on completeness of forage re-moval. The same purpose and concept is used withfrontal grazing except no back fence is provided. Theforward fence gets moved as new forage is needed.

Under more lax grazing management, strip grazingmay occur where the grazing period is similar to thatof an intensive rotational stocking method where thelivestock are moved on a half day to daily basis. Singlestrand electrified fence is used that is portable and canbe removed if need be to facilitate machine harvest.This is useful on the fields that are brought into therotational system during the low forage growth rateperiod. When not needed for pasture, they arecropped. In fact, the field strip grazed may be a cropfield with grazable crop residues, or one seeded to anannual forage crop. Strip grazing serves a usefultransitioning tool between cropping and grazing a fieldin this instance, but does nothing to further enhanceanimal nutrition beyond what the basic rotationalmethod does.

Frontal grazing—Frontal grazing is a form of continu-ous variable stocking. As available forage disappears,more area is opened up for grazing. Again, as withstrip grazing in variable rotational stocking, frontalgrazing is most useful to incorporate a new field intothe area being grazed when forage production is low.Instead of stocking the whole field at once and sus-taining high trampling and rejection losses, the newfield is rationed piece by piece. Forage utilization ishigher, and higher intake rates can be sustained untilthe field is entirely opened up. This method is alsomore appropriate where the forage being grazed eitherhas little or no regrowth potential. Crop residue, some

brassicas, small grains grown for forage use only, andother short-lived annuals are examples. Perennialforages being grazed in this manner should be tolerantof continuous grazing.

When budgeting forage with strip or frontal grazing,care must be taken to not set aside more forage thancan be consumed without a significant decline inforage quality when the last is made available forgrazing. Entry into the field should begin slightlyahead of full forage growth potential to avoid havingto stock animals on overmature forage near the end ofthe occupancy period.

(iii) Seasonal stocking methods—Another class ofstocking methods seek to time access to fields tolengthen the grazing season or avoid harming thepasture area. The two main methods are deferredstocking and sequence stocking. They too can be usedto varying degrees either in continuous or rotationalstocked pastures.

Deferred stocking method—Deferred stocking can bedone to stockpile forages or to keep livestock out ofpasture areas needing seasonal protection for a varietyof reasons. When the grazing season can be extendedby stockpiling forages (i.e., tall fescue) that maintaintheir quality well, some pasture area is deferred fromfurther grazing to allow the forage growing there toaccumulate. Later on, this area is reopened for grazingwhen the other pasture areas are no longer producinggrazable forage or need a recovery period.

Another form of deferred grazing is delaying the stock-ing of a pasture because it is too wet. Other pastureareas are selected that are drier to avoid damaging thesod and destroying soil structure. Soils when wet cancompact severely. It is reversible only with mechanicaltreatment. On saturated soils, hoof prints are leftbehind that trap water and keep the site wetter longerthan normal. The act of leaving these deep hoof im-prints is called either poaching or pugging.

Deferred stocking may be used to protect riparianareas from grazing at critical times of the year. An-other use might be to protect ground nesting birdhabitat from disturbance until brood leaves the nest.Deferred stocking is also used where part of the pas-ture area is not needed for grazing until forage produc-tion slows down. This land typically is machine har-vested to conserve the early growth and then stocked



Chapter 5

once sufficient forage is available for grazing. Deferredstocking may also occur on paddocks that are slow torecover for a number of reasons. They may be skippedover during a rotational cycle or two. A typical sitewould be a droughty soil paddock.

Sequence stocking method—Sequence stocking takesadvantage of the seasonality of forage production. Itintegrates forages with differing seasonal availabilityinto a diverse group of pastures. All fill a seasonalniche to supply enough forage to meet demand by thegrazing herd. Review figures 5–14 through 5–16 andTable 5–2. Sequence stocking attempts to lengthen thegrazing season or fill forage production shortfallsduring the grazing season. Winter small grains mightbe grazed in late winter and spring, then early matur-ing cool-season perennial pastures next, followed by alater maturing cool-season perennial pasture, followedby a warm-season perennial or annual pasture, se-quencing back to a cool-season pasture, and followingup with a post harvest crop residue field and, wherewinters are mild, a winter annual pasture. Dependingwhere the farm or ranch is situated in the country, allor part of these seasonal pastures and others notmentioned can be integrated into the forage produc-tion system. This stocking method attempts to reducestored feed production and consumption to an abso-lute minimum.

(b) Accelerating practice—Nutrient management

Nutrient management on pasture differs from foragecrop production nutrient management in two respects.First, most nutrients are recycled within a pasture'sboundaries (fig. 5–31). Few of the nutrients broughtonto the pasture as feed supplements, manures, atmo-spheric deposition, or commercial fertilizer leave itsboundaries as animal products.

Second, nutrients can be redistributed unequally onpastures by preferential animal movement. Shadyareas, watering sites, laneways, salt blocks, rubbingareas, natural waterbodies, windbreaks, buildings, andsunning areas can cause a disproportionate amount ofdung and urine spots to be deposited in localizedareas. This redistribution of nutrients can cause plantnutrient deficiencies in some areas and excess nutri-ents in other areas. For instance, rates of nitrogen (N)

application at urine spots can range from 200 to 900pounds per acre. Sometimes the rate is so high as tocause plant burning.

Because of the high application rate, loss of N at urinespots through leaching out of the root zone is possiblein high rainfall areas. High losses of urea N at urinespots during dry weather also occurs. From 15 to 18percent of the total N can be lost within 2 days ofurination. The drying of the surface causes the urea tohydrolyze to ammonium. This raises the soil pH in alocalized area that causes the ammonium to breakdown into ammonia, a gas, and a hydrogen ion. Windyconditions speed the process of ammonia volatiliza-tion. Surface runoff may also carry nitrogen and phos-phorus (P) to receiving water if concentrated livestockareas are near open water and soil infiltration is low asa result of low vegetal cover or tight, compacted soils.

Phosphorus and potassium (K) levels are rather stablein pasture soils. Pastures should be soil tested every 4to 5 years for these two elements. Plant available Pand K should be built to the optimum levels for the soilseries sampled. If the soil is already at the optimumlevel for these two nutrients, no further response inforage yield will occur with the addition of manure orcommercial fertilizer containing these elements (fig.5–32). Normal recycling of the P and K through ran-dom placement of dung and urine should maintainlevels. If much supplemental feeding of hay, grain, orminerals occurs, soil P and K levels tend to slowlybuild in the pasture soil. Legumes are heavy users, butinefficient gatherers of phosphorus and potassium. If alegume component is desired in a pasture, P and Klevels in the soil should be in the optimum to highrange so they can compete successfully with thegrasses.

Soil reaction, or pH level, should also be noted whenthe soil test results return. Keep the soil reactionwithin the range of acceptable forage production. Mostlegumes grow best in a slightly acid to neutral soil.Where aluminum toxicity can inhibit forage growth,maintain soil pH at 5.5 or higher. Rhizobium activity,symbionts that fix nitrogen in legume root nodules, isalso reduced for most strains of Rhizobium as the pHfalls below 6.0.

Chapter 5



Figure 5–31 Nutrient cycling in a pasture ecosystem (adapted from Barnes, et al. 1995)

Nitrogen is generally the major limiting nutrient inpastures. As mentioned before, it can leave by threepathways: volatilize, leach, or run off. The distributionof dung and urine under even the best of circum-stances is uneven. On an annual basis, a highlystocked pasture receives excreted N on less than 35percent of its area. Where the stocking rate is an AUper acre, only 16 percent of the pasture surface re-ceives any excretal N.

Intensive rotational stocked pastures tend to have amore even distribution of manure than do continuousset stocked pastures. However, it is extremely impor-tant that water, feeding areas, salt and mineral boxes,and shade are evenly distributed on a rotational pas-ture. If not, dung and urine spots can be distributedjust as poorly. Poorly laid out paddocks and single

source water, feeding, salt and mineral, and shadeareas cause livestock to camp at these sites just asthey do on continuous set stocked pastures. Longlaneways to these attractive areas can receive much ofthe excreta as livestock traverse back and forth fromgrazing area to camp site.

Nitrogen can be supplied for forage growth two ways:apply a nitrogen fertilizer or add a legume componentto the forage mixture growing on the pasture. Whenapplying nitrogen fertilizers, organic or inorganic,rates of application should be low enough to preventluxury consumption by plants and avoid leaching ofnitrate through the root zone. Overfertilization ofsummer annual grass pastures with N can also causenitrate and prussic acid poisoning in livestock if plantgrowth is stressed by frost or drought. Early springgrowth applications must be avoided on all pastures

Machine harvestedplant products

Plant uptake Dung Urine

Ungrazed foragedead roots (N)

Volatilization(N)

DenitrificationDeposition (N,S)

Supplementaryfeed

Animal products

Runoff, Erosion(N & P)

Leaching (N)

Runoff, Erosion (N & P)Leaching (N)

Transfer toheavy use areas

Plant

Ingestion

Atmospheric

Exchange

Soil

Animal

Excretion

Water

WaterLegume symbiotic(N) Fixation

Fertilizer(manures or chemical)

Unavailableplant nutrients

Availableplant nutrients

Residues

Soil organic matter

Plant Animal

Weathering

Immobilization(N,P,S)

Mineralization

P & K fixation



Chapter 5

Figure 5–32 Yield response curve to indicated range of plant available nutrients from soil test results* (from Serotkin 1994)

Low

Soil test level

HighOptimum Excessive

Yie

ld

Critical nutrientrange

Deficientrange

Adequate range Toxic range

Loweredresponse

to fertilizer

High responseto fertilizer

No responseto fertilizer

Reducedyields

* Note once optimum level for a plant nutrient is reached, no further yield response occurs.

where grass tetany is know to be a problem to live-stock. If a legume component is desired to improveanimal intake and nutrition, N fertilizer rates andtiming should also avoid giving the grasses a competi-tive advantage over the legumes.

Legumes can fix atmospheric nitrogen by acting as ahost to Rhizobium bacteria. See table 5–5, Seasonaltotal of nitrogen fixation by forage legumes and le-gume-grass mixtures. During the first year of legumegrowth, no nitrogen is transferred to the grass compo-nent of a pasture sward. Thereafter, nitrogen is trans-ferred from the legume to the grass in substantialamounts, providing up to 50 percent of the N require-ment of some grasses. Depending on the legumespecies and its distribution and percent of stand, Ntransfer to cool-season grasses ranges from just a fewpercentage points to 50 percent. Stand life average Ntransfer to grasses from the legumes accounts for nomore than 25 to 30 percent of cool-season grass needs.

It appears with some warm-season grasses that com-patible legumes grown with them may be able tosupply perhaps all their N needs. Ideally, to be effec-tive in transferring fixed N to grasses, the legumeshould make up at least a third of the stand and bewell dispersed. Maintaining the legume component inthe stand requires good grazing and nutrient manage-ment. Even then, diseases and insects can still take outthe legume component. Maintaining legumes in apasture takes a concerted effort to reintroduce themby overseeding or renovating the pasture from time totime.

Nitrogen fertilizer additions, whether from fertilizersor N fixing legumes, induce long-term soil acidificationin the topsoil and subsoil. When added to the soil, 100pounds of urea, whether from urine or chemical fertil-izer, requires 84 pounds of calcium carbonate (lime) toneutralize the soil. In fact, all nitrogen carriers contain-ing either ammonia or urea acidify the soil. Soil acidifi-cation results in the loss of exchangeable cations, of

Chapter 5



particular importance, calcium (Ca) and magnesium(Mg). Soil acidification is heightened in the surfacelayer (0 to 2 inches) of the soil of permanent pasturesin particular. The N fertilizers are generally surfaceapplied and no, or infrequent, tillage takes place tomix any lime from deeper in the soil profile with thesurface soil.

Sulfur (S) is a secondary nutrient of critical impor-tance to forage growth. It is a component of chloro-phyll and proteins. Sulfur is similar to N in somerespects in that it can be an atmospheric contaminantthat is deposited on the soil and can also be immobi-lized by microbial breakdown of soil organic matter.With the advent of high analysis fertilizers, little or nosulfur is added to the soil when commercial fertilizersare applied unless they are specifically formulated tocontain sulfur. Sulfate had been used widely as acarrier for nitrogen and potassium fertilizers. Also, asacid deposition is brought under control, less sulfur isbeing deposited on the soils from the atmosphere. As aresult, sulfur deficiency symptoms are beginning toreappear, especially in legumes. For optimum plantgrowth, the N:S ratio in plant tissue should range from14:1 to 16:1 when N content of the plant is adequate.

Calcium and Mg are important secondary nutrientsfor plant and animal nutrition. On calcareous soils,both generally are adequate. On acid soils these nutri-ents can be in low supply unless the soils are limedregularly. Magnesium is particularly important topastured cattle and sheep. Areas deficient in magne-sium or areas that are overfertilized with K, N, orheavy applications of manures containing N and K cancause seasonally low dietary levels of Mg in the forageingested by livestock. This causes low blood plasmalevels of Mg (hypomagnesemia or grass tetany) inlivestock, especially freshening females. Death canresult if not treated quickly or prevented by agronomicor feeding practices. Agronomic practices to avoidhypomagnesemia are liming soils with dolomiticlimestone (calcium and magnesium carbonates) andsplitting N and K fertilizer applications. If poultry litteris used as a nutrient source, prudent rates must beapplied and preferably after high grass growth rateperiods. Magnesium supplements can also be fed tolivestock prior to calving or lambing and before flushgrass growth periods.

Table 5–5 Seasonal total of nitrogen fixation by foragelegumes and legume-grass mixtures 3/

Legume or legume-grass Total N2 fixation(lb/acre) 2/

Alfalfa 70 – 300

Alfalfa - orchardgrass 13 – 121

Alfalfa - reed canarygrass 73 – 226

Alsike clover 119

Berseem clover 55 – 210

Birdsfoot trefoil 44 – 100

Birdsfoot trefoil - reed canarygrass 27 – 116

Crimson clover 94

Hairy vetch 100

Ladino clover 100 – 179

Lespedeza (annual) 85

Red clover 20 – 200

Red clover - reed canarygrass 5 – 136

Subterranean clover 52 – 163

Subterranean clover - soft chess 19 – 92

Sweet clover 119

White clover 103 – 114

White clover - bahiagrass > 270

White clover - bermudagrass 135

White clover - Dallisgrass 143

White clover - tall fescue 187

1/ Sources: Ball, D.M., et al. 1991, Southern Forages; Barnes, R.F.,et al., 1995, Forages; Chessmore, R.A., 1979, Profitable PastureManagement; and Graffis, D.W., et al., 1985, Approved Practicesin Pasture Management.

2/ Ranges given where available. Single values are probablemaximums or the averaged result of one experiment. Highlyvariable. Do not use as absolutes.



Chapter 5

Use of pastures as sites for manure disposal must bedone with some prudence for other reasons. Sheep aresusceptible to copper (Cu) toxicity. Sheep should notbe allowed to graze pastures with recent applicationsof poultry litter or swine manure. Both manures maycontain high Cu concentrations since Cu salts are fedas wormers to both livestock types. High rates ofpoultry litter applied to endophyte infected tall fescuepastures can also intensify bovine fat necrosis out-breaks. Ideally, no more than 4 tons per acre of poultrylitter should be spread on tall fescue pastures. It alsois important not to overload pasture soils with P and Keither. As mentioned before, these nutrients are slowto leave the pasture as animal products. Long-termaccumulations of these nutrients can induce deficien-cies of other essential nutrients in plants and animals.Recently, high levels of K in pasture grasses have beenimplicated in cases of milk fever in freshening dairycows grazing them.

Two trace elements of critical importance to livestockproduction are copper and selenium (Se). Both areessential for livestock health, but have a narrow rangeof acceptable concentration in feedstuffs. Inducedcopper deficiency in livestock can occur in areaswhere soils contain elevated levels of molybdenumand sulfur. Selenium deficiencies occur in the PacificNorthwest and the Eastern third of the United States.In semi-arid parts of the U.S., selenium may be presentin forage in toxic amounts. Soils deficient in these twoelements cannot be safely supplemented with eitherCu or Se fertilizers. Overfertilization with either iseasily done. Feed rations must be balanced throughsupplementation where Cu and Se deficiencies occuror through dilution when forages containing toxicamounts of Cu and Se are produced.

The trace element cobalt (Co) can be safely appliedas a fertilizer. It is required in energy metabolism inruminants and for the health of Rhizobia in legumeroot nodules. Pastures deficient in cobalt can befertilized with low rates of cobalt sulfate (1.5 to 3ounces per acre of Co).

Another trace element of importance is boron (B). Itimproves legume growth. Boron can be added to thesoil using borax or B-containing mixed fertilizer. Itmust be added in low amounts (0.5 to 3 pounds of Bper acre) to avoid toxicity problems.

Grazing management can be helpful in managingnutrients on pasture. Conscious efforts can be made toensure the best distribution of dung and urine as ispossible with the setting involved. Multiple wateringsites no greater than a quarter mile away from eachother is a start. If the water is not close to the grass,livestock once at the watering site will tend to campthere. Grass will be underused away from the wateringsite and receive little manure. Meanwhile, the grassclose to the watering site will be overgrazed andreceive all the manure. In multiple paddock layouts,water must be at each paddock. Ideally, water isplaced towards the middle of the paddock if the lengthof the paddock exceeds a quarter mile. If water is notavailable at each paddock, the laneway serving thepaddocks will end up with a disproportionate amountof the excreta.

Salt and mineral blocks should not be placed close toother attractive areas. This encourages livestockmovement and dispersion of excreta. Shade and hayfeeding areas are best kept on higher ground awayfrom streams. Ideally they should be positioned onknolls or hilltops. Manure and urine will be concen-trated there, but runoff events tend to wash some of itback down the slope.

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(c) Accelerating practice—Pastureplanting

At times, grazing management cannot provide thedesired species mix or quantity and quality of forageon a pasture in a timely fashion. Also the seedbankmay not store enough seed of the desired speciesmissing from the stand. When confronted with theseproblems, planting seeds or sprigs is necessary toachieve pasture production objectives. Several goodreasons to resort to pasture planting include:

• Reintroduce legumes into the stand.• Replace low producing common varieties of

grasses with improved varieties.• Replace grasses with low palatability or high

alkaloid content with improved varieties of thesame species or altogether different species.

• Replace disease or insect prone grasses or le-gumes with new resistant varieties.

• Plant forage species on land being brought backinto pasture use as part of a crop rotation cycleor as a land use change.

• In lieu of other corrective measures to changethe site conditions of a field, replace poorlysuited forage species presently growing on thefield with forages better suited to soil and cli-mate.

• Replace some existing forage stands on part ofthe land unit to better match livestock foragedemand throughout the year by providing se-quential stocking areas of high forage availabil-ity. (For instance, reintroducing some warm-season grasses on a part of a land unit currentlywithout any warm-season pastures to providesummer pasture when cool-season grasses aredormant.)

• Plant annual forage crops to extend the pastureseason into a dormant period for the perennialspecies growing on the site or provide emer-gency or supplemental feed when other pastur-age is low in quality, quantity, or both.

Keep pasture forage mixtures simple, not more thanfour species. In permanent pastures the soil seedbankprovides several adapted alternative forage speciesanyway. Therefore, it is not real critical to achieveinstant diversity and run the risk of planting a mixturethat really does not persist as formulated anyway.Select species that have similar maturity dates andpalatability, compatible growth characteristics, andare adapted to the same soil and climatic conditions.

Use certified seed to get superior cultivars of knownresistance to pests common to the production areaand high seed quality of known purity and germinationpercentage. On soils with variable drainage, plantingseveral forage species with differing adaptability to thedrainage conditions on the site might be warranted.However, much of the seed sown will end up in placeswhere the particular species will not thrive or perhapssurvive. Therefore, do this only on sites where randomvariability of drainage is too complex to seed areasseparately with different seeding mixtures.

Pasture plantings should be accompanied by goodnutrient management practices. Soil tests should betaken to ensure the nutrient status of the soil is ad-equate for the species being planted. When the soilsample is sent in for nutrient analysis, it should statethe species to be planted and the yield goal desired. Ifsoil amendments of lime or gypsum may be required,take soil samples at least a year in advance of theplanting time. Soil amendments should be applied atleast 6 months ahead of planting to have sufficienttime to react with the soil. On soils that tend to fixphosphorus, fertilizer should be band applied at plant-ing rather than broadcast over the field.

Pasture plantings should also be accompanied by goodpest management practices. Weed control before andafter planting is critical. Many of the forage species areslow to germinate and establish themselves. Weedsthat survived seedbed preparation or that germinateafter planting can quickly shade and smother outyoung forage seedlings. Late season seedings of cool-season forages can avoid the heaviest weed pressure.Undesirable stoloniferous or rhizomatous grasses andbroadleaf weeds should be killed with an herbicideseveral weeks in advance of tillage. No amount oftillage effectively controls them. Damping-off of seed-lings can be controlled with fungicides labeled for use.Insecticides should be used as needed to controlinsect feeding. Severe plant thinning to total loss ofstands can occur if insect pressure is high while seed-lings are young and tender. This can also occur if slugfeeding is high.

If pastures are to be tilled prior to planting, theyshould be grazed closely the year before planting toreduce the amount of organic residue incorporated.Otherwise, getting a seedbed that is firm, smooth, andnot too trashy is difficult. This leads to overworkingthe soil to get it firm, smooth, and free of large



Chapter 5

amounts of residue. Overworked soils can crust overand dry quickly. This can jeopardize seedling germina-tion and emergence. Tillage for forage establishmentshould only be used on fields with little or no erosionpotential.

Once fields have been tilled to incorporate soil amend-ments and fertilizers and to produce a firm, smooth,granular seedbed, several implements are available tochoose from to apply seed. Drills, cultipacker seeders,broadcast seeders, and band drills are the primarytypes. Band drills put down a band of fertilizer be-tween rows of drilled seeds. Drills without presswheels and broadcast seeders should be followed with aculti-packer to get better seed-to-soil contact. Otherwise,these two seeding implements need to be followed by asoaking rain to get good seed-to-soil contact.

Forage seedings may be seeded clear (forage seedonly) or with a companion crop. Clear seedings get afast start, but weed growth generally needs suppres-sion. Mowing or top grazing weeds off above forageseedlings is one method. Applying herbicides is an-other. However, there are no herbicide products thatcan be used on mixed grass and legume seedings.Straight grass mixtures can be treated with broadleafherbicides labeled for use. Straight legume seedingscan be treated with either broadleaf or grass herbi-cides labeled for the legume being protected. Compan-ion crop seedings are not generally recommendedsouth of the 39th parallel.

Bermudagrass may also be established by using sprigs,the stolons and rhizomes of the grass. Tillage shouldcommence in the fall to kill existing sod where thebermudagrass is to be planted. It is left rough to cutdown on soil erosion. Sprigs are dug with a sprigdigger or spike tooth harrow from a nursery of aknown cultivar. They are windrowed with a sidedelivery rake and can be baled to improve handlingease. Sprigs are planted either with a sprigger orbroadcast, disked in, and the ground rolled to improvesprig-to-soil contact. To avoid weed competition,herbicides should be applied immediately after sprig-ging to control competing grasses and broadleaves.

Timing of plantings is regionally dictated. Generalstrategies are to plant when moisture and temperatureconditions are most favorable for the species beingplanted, enough growing season is left to ensurematurity or overwinter survival, and weed, disease,

and insect pressures are best avoided. For instance,late summer to fall seedings of legumes can avoidmajor weed competition and damping-off diseases insome areas. However, in other areas, they may suc-cumb to late season disease problems, such asSclerotinia crown and stem rot.

Sod seedings (no-till) have become a more popularway of seeding pastures since improved no-till drilldesigns have become available. Sod seedings can beused on sites susceptible to high erosion rates and onsoils that tend to dry out quickly or crust if tilled. Tostart, suppress or kill existing vegetation. The decisionto suppress or kill depends on the value of the foragespecies remaining on the site and their abundance. Ifenough desirable forage plants cover the site, thesuppression option can be chosen. Vegetation may besuppressed by grazing close for several weeks beforeplanting. Ideally, seeding should come later in thegrowing season when it is unlikely that the suppressedvegetation will come back strong. This is very usefulwhen planting cool-season annuals in warm-seasongrass pastures, such as bermudagrass.

Suppression can also be done using a burndownherbicide, one that burns back the green growth ofperennials, but does not kill the crown or roots. Thisherbicide can either be broadcast or banded. Bandspraying to leave alternate strips of green and burnedback vegetation allows for an early return to grazingwhen spring sod seeding a legume into a grass pasture.Weed suppression is also greater. There is less needfor herbicide as well. If the present pasture has littleforage of any value and aggressive spreading lowquality forages and better cultivars of existing foragesare desired, then the existing stand should be killed.Ideally, this should be done towards the end of theprevious growing season for an early seeding thefollowing year. This is particularly needed if unwantedrhizomatous or stoloniferous vegetation is present. Itgives time to react to less than a 100 percent kill andtreat the area again.

A low technology method of sod seeding is frost crackseeding. This is used in areas of the United Stateswhere late winter alternate freeze and thaw cyclescauses the soil to honeycomb at the surface. Success-ful clover seedings can be done in this manner bybroadcasting the seed over the existing sod. Theseseedings eventually come in good contact with the soilduring the freeze and thaw cycles to germinate when

Chapter 5



the soil warms enough to trigger germination. Furtherseed-to-soil contact can be promoted by allowinglivestock to tread the seed in when the soil is firmenough not to become poached badly. They must beremoved before germination.

Seed depth is critical for small seeded forages. Mostrequire a shallow depth (0.25 to 0.50 inch) to get goodemergence and survival. In drier regions, depths mayneed to extend further in the ground (up to 1 inch) toget adequate moisture for germination. Even in thesame MLRA, seed depth must vary according to soiltype. Greater seed depth is required in sandy soil thanin silt or clay loams. Seed depth recommendations forvarious forages should be based on their specificrequirements, surface soil moisture conditions asaffected by soil texture, and time of year of seeding.

Seeding rates should be based on pure live seed, thepercentage of pure seed that will germinate from theseed lot being planted. Seeding rates should be ad-justed for soil textural differences. Sandy soils can beseeded at lower rates than heavy clay soils sinceemergence is less inhibited by soil crusting. Soils withlow water holding capacity should be seeded at lowerrates because they cannot support as many plants assoils with high water holding capacity. Seeding ratesshould be adjusted based on seeding equipment andmethod used. If seed is broadcasted or drilled withoutpress wheels or trailing culti-packer, seed rates needto increase by 25 percent. Seedling mortality will behigh because of the hit or miss soil coverage of theseeds. If clear seeding, adjust seeding rates upward tocrowd out weeds and maximize first year forageproduction.

Mortality is high with forage seedings. Commonly onlya third of the seeds become emerged seedlings. Ofthat, only 20 to 50 percent survive at the end of theestablishment year. Oversown fields, where seed isspun on and lightly harrowed or frost crack seeded,have very high seedling mortality; 10 percent survivalis typical. This is why seeding rates are as high as theyare. For instance, where alfalfa is seeded at the rate of15 pounds PLS per acre, there are 77 seeds per squarefoot. At the end of establishment year, 20 to 50 alfalfaplants per square foot is considered optimal. If 50percent of the seed survived to be plants at the end ofthe establishment year, the number per square footwould be 38. If only a third survived, then 26 alfalfaplants per square foot remain.

Given the cost of seed and the expense of preparingthe ground to plant it, it is wise to take care in plantingit. If the planter used cannot by itself ensure goodseed-to-soil contact, then a pass with a culti-packer orshallow set harrow is worth the time spent. Fungicidesand insecticides can also be effective in reducingseedling mortality. Livestock should not return toosoon to new seedings. Treading damage and ripping ofplants out of the ground during grazing can result.

All legume seed should be inoculated with the properstrain of Rhizobium. Most of the alfalfa and cloverseed sold today is preinoculated. When the seed ispreinoculated, it must be sown before the inoculantexpiration date on the seed tag. Otherwise, it must beretreated with inoculant. For untreated seed or ex-pired treated seed, apply the humus based inoculant tothe seed with a sticking agent just before sowing.

(d) Accelerating practice—Prescribed burning

General rule of thumb: Burn warm-season grasses asneeded. Never burn cool-season pasture forages.

Bermudagrass pastures can be burned a week or soafter the last killing frost in the spring to controlwinter annual weeds, some leaf diseases, and insects,such as spittlebugs. It also removes low quality deadgrass and hastens green-up. Tall warm-season grasses,such as switchgrass, big bluestem, and indiangrass,should be burned periodically in late spring to improveforage quality and remove invading cool-seasongrasses. Burning should take place before any re-growth of the warm-season grasses; otherwise, standthinning occurs.

Burning of cool-season forages is not recommended.In fact, it is a control measure to get them out ofwarm-season grass stands. Despite an early green-upwhen dead residue from previous years is burned off,experimental results have shown substantial de-creases in forage yield for the season after a burn. Anexception to this rule might be where previouslyabandoned/unused forage stands have large amountsof dead, low quality residue and invading brush andweeds on them. In this case a prescribed burn wouldhasten the return to good forage production and killthe brush. First year production would have been lowanyway because forage plant densities had declined as



Chapter 5

a result of long-term shading from mature plant mate-rial and competing vegetation.

Burns should be fast and done when the soil is moistto protect roots and crowns from damage and underlow wind conditions. They should be done by qualifiedpeople in accordance to local statutes and the NRCSPrescribed Burning conservation practice standard.

(e) Accelerating practice—Irriga-tion water management

Irrigated pastures are commonly used to complementrangeland and other types of permanent pasture. Theycan provide dependable pasture when other pasturesare dormant. These pastures can also be used toachieve higher average daily gains on calves andstocker cattle. This results in more pounds of beef forsale at the end of the grazing period when the cattleare moved to the feedlot. Similar production gains canbe had with other livestock types.

Irrigation of pasture is put to best use in areas whereprecipitation and stored soil moisture fall well short ofpotential evapotranspiration needs of the pasture.Water ends up being the limiting nutrient during theseasonal height of pasture growth. Figure 5–33 showsa typical yearly water budget. In the example dis-played in this figure, nearly 11 inches of water isneeded to meet the pasture’s need for water during thesummer months. Plant available soil moisture for thisparticular soil and forage species is 4 inches. Thiswater is used up during the spring months since plantuptake requirements exceed precipitation by mid-March. After plant growth begins to slow down in thefall, precipitation exceeds plant uptake. Soil moisturebegins to be restored. Once plant available water isrestored, the rest entering the soil becomes surplusand leaches below the root zone. Rainfall exceedingthe soil's infiltration rate will runoff as well.

Irrigation water management described here focuseson management only as it specifically relates to pas-ture. A more in-depth description is in the section,Forage crops.

Figure 5–33 Typical water budget showing where the seasonal need to irrigate occurs and the magnitude of that need (fromBaver 1961)

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Chapter 5



Many of the forages grown for pasture have relativelyshallow root systems or at least have 70 to 80 percentof their root mass in the first 4 to 6 inches of the soil.This limits the amount of water that can be stored inthe effective root zone for these forages. Irrigationapplications need to be more frequent and at relativelylow rates to be certain the water is used by the foragesand not percolating by their roots. Deep percolation issometimes necessary to leach salts and sodium fromsaline and sodic soils. On these soils heavier applica-tion rates are necessary to keep the salts from accu-mulating in the root zone and burning the forages.When irrigating forage mixtures, the species havingthe shallowest root system generally controls theirrigation schedule. It will suffer the most if irrigationis delayed.

Flood and sprinkler irrigation are the most commonlyused pasture irrigation methods. When flood irrigationis used, large heads are required to get quick coverageand uniform distribution of water over the floodedarea. This is because pasture sods reduce overlandflow velocities quickly and create an absorbent soilsurface. The distance between head ditches that areused to flood the pasture must be close spaced be-cause of these vegetal retardance and soil porosityfactors. If not, some areas of the pasture receives all ormost of the water while others remain too dry for topyields. When feasible, land smoothing should be doneto remove high and low spots in the pasture.

Sprinkler irrigation gives a more uniform water appli-cation especially on rolling topography and highlypermeable soils.

Rotation grazing of irrigated pasture facilitates thescheduling of irrigation after a grazing event. Thisavoids having livestock on wet soil where poachingdamage can occur to the sod. Having the pasturedivided into two or more subdivisions, allows themanager to graze one subunit while irrigating anotherimmediately after the livestock are removed. Livestockshould remain off the irrigated subunit long enough forthe ground to firm up and permit enough regrowth tomeet available forage requirements. Set minimumallowable grazed stubble heights on irrigated pastureto achieve rapid regrowth recovery of the preferredspecies. Maintenance clipping of irrigated pasturesminimizes selective grazing, enhances forage qualityby setting all plants back to early vegetative state, andthereby increases utilization rates by livestock.

In arid regions, irrigated pasture soils generally arelow in nitrogen and phosphorus. Legume-grass mix-tures can overcome the nitrogen deficiency. Fertilizingwith superphosphate fertilizers promotes excellentgrowth of these forages. Soil nitrogen tends to buildwith time as long as legumes remain a component.

Irrigated pasture can be used in rotation with othercrops to improve soil tilth through increasing soilorganic matter content and soil particle aggregation.Being under a crop rotation also allows the pasture tobe renovated on a scheduled basis to maximize forageproduction when it is in pasture.

Annual forage crops grown on irrigated pasture ben-efit by being irrigated just before or immediately afterplanting. Germination and initial growth proceedquickly and produce grazable forage faster and morepredictably than rain-fed crops. Irrigated pasture alsoenhances cool-season forage growth during the mid-summer slump period. The lack of moisture is morecritical than the high temperatures in suppressing theirgrowth

(f) Facilitating practice—Waterdevelopment

To get maximum use of available forage, water mustbe within a quarter mile of the forage producing siteon level to undulating topography. Where slopesexceed 25 percent, watering sites should be no morethan 600 feet away, 1,200 feet between watering sites.When distances get greater than this under the slopeconditions mentioned, forage past those distances arelightly grazed if at all. At greater distances to waterespecially with fence barriers blocking movement,pastures become overgrazed near the watering siteand undergrazed at more remote locations.

Water development can take many different forms.Several forms are described in this section.

(1) Pipelines

Most farmsteads and ranch headquarters have wells.Where distances are short to pastures, it may be easierand cheaper to extend pipelines from the well to watertroughs. Many pipelines using polyethylene tubing arelaid across the ground surface or buried. Hydrantswith connecting valves are located at convenientintervals to temporarily attach water hoses that lead to



Chapter 5

a water control valve in a water trough. Polyethylenetubing is preferable to other materials because of itsresistance to corrosion, resiliency, and lower frictionresistance to water flow. In locales where waterfreezes in the winter, exposed pipelines need to bedrained of water or have sufficient water flow-throughto remain unfrozen. Buried pipelines need to be placedbelow the frost line, or drained during the wintermonths if rock limits depth of excavation. The deci-sion to bury or let the pipelines lie on the surfacedepends on the permanency of the pasture layout,amount of vegetal cover present to shade the pipe, andultimate temperature of the water at the trough. Watertemperature above 75 degrees Fahrenheit decreaseswater intake and milk production in dairy cows. Lac-tating dairy cows produce the most milk when drink-ing water is between 50 and 65 degrees Fahrenheit.

(2) Springs or seep areas

Springs or seep areas often occur in pastures at eleva-tions above creek and river bottoms. These areas areuseful as water sources for livestock on pasturesremote or isolated from headquarters or farmsteadwells. Livestock normally use these water sources asthey naturally exist. However, this can lead to degrada-tion of the seep or spring area. Eroding banks, waterfouled with excrement and mud, poaching of the wet

soils around the fringe of the open water, and damageto riparian vegetation are the most apparent problems.Weaker seeps and springs can be so badly disturbedthat they become unreliable watering sites exceptduring high flow periods. Spring developments areused to provide a reliable source of high quality waterto livestock, exclude livestock from the riparian areaof its source, and convey the overflow back to anadequate outlet with a minimum of contamination andwarming. Figure 5–34 shows a typical installation. Ithas three major components: a collection system,pipeline, and trough.

(3) Ponds and streams

Ponds and streams are often used as water sources. Ina pasture setting, limiting access to these watersources helps to prevent contamination of the waterby excreta. Coliform bacteria counts can often bequite high in these situations. Blue-green algae bloomscan occur during hot weather in nutrient rich ponds.Livestock deaths have resulted from blue-green algablooms when the concentration of toxins was high atthe water surface. Basically, the water quality can beless than desirable for the drinkers as well as thedownstream recipients. Several options are availableto limit or remove livestock from open water sourcesaltogether.

Figure 5–34 Spring development showing collection system, pipeline to and from trough, and trough

Paved area

Overflowpipe

PipelineStand-pipes

Trough

Over-flow

Inflow

No fence is needed if thecollector tile has about3 feet of cover and thespring area will dry up

Gravel totop of tile

Concrete or claywall below tile

4-inch drain tile

Collection basin(18-inch sewer tilerecommended)

Inlet sewer tile sealed joints

Antiseepcut-off wall

Trench tointerceptwater

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Chapter 5



(i) Controlled access options—An option thatlimits access is a paved ramp or stream ford. Pavedramps can be used at the shoreline of a pond to allowcattle to drink, but not wallow around on the muddypond bottom. Siting of these ramps is critical so as toavoid severe trailing erosion and resultant fouling ofthe water and burial of the pavement. The ramp shouldnot be near the inflow point of the pond and not on theembankment or in the emergency spillway whereprovided. Paving material can be crushed rock, con-crete, asphalt, or other durable paving material. Infrost prone areas a good base is required to preventfrost heave damage to the pavement. The rest of thepond and any dam or spillway are fenced off to leave avegetative filter of grass between the grazed area andopen water. At the ramp the fence extends into thewater at the sides and has a front fence that preventswading beyond the ramp.

Stream fords are constructed in a fashion similar topaved ramps at points where livestock show an incli-nation to cross. Stream fords not only provide water,but allow access to pasture areas on either side of thestream. They should be sited and constructed toprevent trailing erosion sediment from flowing directlyinto the stream. Pavement should extend to an eleva-tion equal to the top of upstream streambank. Pavingmaterials should be resistant to dislodging caused bythe maximum expected water velocity achieved atbankfull flow. Concrete grid pavers or confinementfloor slat seconds are good choices because they arenot likely to dislodge and form a cleated surface toprevent livestock from slipping on the wet surface.Stream corridor fencing ordinarily is combined withthis practice to get full benefit of the stream ford.Some contamination of the water will still occur, butthere is a substantial reduction in sediment loading.Paved areas can be made uncomfortable enough tomake livestock move through faster than if it were anatural site that was easier on the hooves and legs.Where fences are used with this practice, flood gatesof various designs are used up and down stream toflank the ford. They can be simple breakaway devicesto swinging gates, or simply a one strand electrifiedwire with a curtain of chains or wires hanging downwithin a few inches of the water and stream embank-ment.

(ii) Pond and stream devices—Gravity feedpipelines or siphons can provide water from pondsand streams if proper elevations can be achieved in areasonable distance within the pasture. These pipe-lines extend to a trough or series of troughs that eitherare equipped with a shutoff float or overflow standand outlet pipe. The inlet of the pipeline must beequipped with a filter or screen to prevent sedimentand algae from flowing through the pipe and foulingthe water at the trough or clogging float valves.

A water ram is another device that can be used. In thiscase water is needed at higher elevations than that ofthe pond or stream. The water ram is dependent onsome pressure head to pump water to higher eleva-tions. It is convenient to use in rugged terrain wherepastures have no other source of pressurized waterand no high elevation sources of gravity flow water.This device requires someone experienced in itsinstallation. It requires careful design to deliver theproper amount of water under the specific site condi-tions with which it must work. The placement of theinlet pipe and its intake site is also critical. If not doneproperly, the intake can be silted over. The ram itselfmust be placed in a safe area so that it is not dislodgedor destroyed during a flood event. It may be piped to astorage tank or reservoir before going to a trough. Thesiting of a ram should be accessible to the operator ona daily basis to check for proper functioning.

A nose pump or pasture pump is another device usedto pump water for livestock. They pump water usingthe force produced by a drinking animal when itpushes against a nose plate while drinking water froma cup positioned underneath the nose plate. When theanimal quits drinking after emptying the cup of itswater, the piston behind the nose plate goes back tothe rest position. When it does this, water is drawninto the cup from a hose that goes to a pond or stream.The inlet must be protected from sediment. A naturalpool should be selected instream that remains rela-tively free of bottom sediment. These pumps areappropriate for small herds that have immediateaccess to them. They are inappropriate where thedistance is far enough to cause the herd to go enmasse to drink. The dominant animals will drink andspend the rest of the time harassing the others. Figure5–35 shows a typical pasture pump installation.



Chapter 5

Figure 5–35 Pasture pump installation

Water troughs are made of several materials: galva-nized steel, reinforced concrete, polyethylene, rubber(including used tires), and wood stave. Water troughscome in all sizes. Their size depends on:

• Number of head being served, their daily or onetime intake

• Number of head at the trough at any giveninstance

• Delivery rate of the pipe or valve delivering thewater

• Whether the trough is being used as a storagereservoir as well as a watering site

If water troughs are close by the grazing resource andrefill quickly, they can be small because animals comeup individually or in small numbers to drink. If the tripto the water trough requires a long walk, the animalstend to herd up and make the voyage together. If thetrough is being served by a low flow system (less than3 gallons per minute), the trough should be at leastlarge enough to handle the whole herd at one time. Seetable 6–7 (page 6–12) in Chapter 6, Livestock Nutri-tion, Husbandry, and Behavior, for water requirementsfor livestock given in gallons of water drank per day byvarious types of livestock. These daily requirementsvary widely. They depend on the water, protein, andsalt content of the forage and feed being eaten; quality

of the water being drunk; exertion expended duringdaily routine; air temperature; shade availability; andhumidity levels. The values in table 6–7 should not beconsidered absolutes; however, they can give anestimate of how much water needs to be supplied on adaily basis.

Plan to deliver enough water to handle the extremesfor the area. Livestock caught short on a hot day couldbe disastrous to their health and the owner’s wealth.Water troughs should be constructed or placed toprevent entry by livestock. This protects the animalsfrom injury or death and keeps the water cleaner. Thetroughs also need to be resilient to pushing and resis-tant to being tipped over by livestock.

Shut-off valves of various types are needed at troughswhere water overflow pipes are not practical. Thesevalves need to be durable to prevent livestock fromdislodging or breaking them. Valves with free-floatingfloats tend to be attractive to curious livestock. Ifwithin reach, the valves can be broken from theirmoorings, and water will overflow the trough. Placingthem under a fence or other rigid or electrified objectcan protect them. Floats that are clamped to the sideof a trough should be securely fastened and protectedfrom being rubbed on and uplifted.

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(4) Water quality

Water quality is extremely important to consuminglivestock. See table 6–8 (page 6–12) in Chapter 6,Livestock Nutrition, Husbandry, and Behavior, forwater quality standards for livestock. New sources ofwater should be tested to see if they are suitable forthe livestock to be watered. Important water qualityparameters are nitrates, sulfates, total dissolved solids(TDS), salinity, bacteria, pH, and pesticide residue.

Nitrates can kill ruminants if ingested at high dosages.The nitrates are converted to nitrites in the rumen.These are absorbed in the blood stream. The nitritesattach themselves to the blood hemoglobin formingmethemoglobin. This does not allow the blood to carryoxygen, so the animal can die of asphyxiation. Animalsso affected have chocolate brown blood. Nitrates atlower concentrations can cause reproductive prob-lems in adults and reduced gains in youngstock.

High sulfate and high TDS or saline water causesdiarrhea. Dehydration may occur in severe cases. Saltwater toxicity can also upset the electrolyte balance ofthe afflicted animal as well.

Bacteria, especially total bacteria count, can increasecalf losses, cause animals to go off-feed, increaseinfections, and cause chronic or intermittent cases ofdiarrhea. Acidic water (<5.5) or alkaline water (>8.5)can cause acidosis and alkalosis, respectively. Animalsbecome unthrifty, go off-feed, have infertility prob-lems, and get infections easier. Although most pesti-cides are not directly harmful to livestock, the milkand meat produced by them may become contami-nated if not broken down during digestion or elimi-nated.

The organophosphates are most dangerous to live-stock directly. As mentioned briefly earlier, blue-greenalgae can kill livestock drinking from ponds contami-nated with them. It happens suddenly without warn-ing. A brief algal bloom and wind drifted accumula-tions at the drinking site can spell quick death. Thereis no way to test ahead of time, just a post-mortem.This perhaps is the best incentive not to allow live-stock direct access to ponds at least during hot, dryweather. The cost of one animal lost can build severalrods of fence and pay for a stock tank.

Watering site layout on improved pastures needs toprovide even distribution of grazing to enhance forageutilization. Livestock can travel longer distances thanwhat is needed to get optimum forage utilization.However, other improvements will fail to deliver if theanimals do not graze areas well remote to water. Withrotational pastures a trough or other watering facilityshould be in each paddock. Depending on layout anddistances involved, two to four paddocks might beserved by one watering facility strategically placed at afenceline or the intersection of two fencelines. Thewatering facility must be sized correctly and posi-tioned to avoid crowding. In continuously grazedpastures, troughs or other water sites should be evenlydistributed. This avoids having underused or overusedareas or corners of pasture.

(g) Facilitating practice—Stockwalkways or trails

On improved pastures, stock walkways or trails aremost often referred to as lanes or laneways. Theyfacilitate livestock movement. The lanes may bepaved, unpaved, or a combination of both. Dairypastures are better served by paved laneways becausethe cattle need to move back and forth from pasturesto the milk parlor at least twice daily. Paving is alsocritical where laneways must cross wet soils to pro-vide the most efficient or the only way to get to allpasture areas.

Constructed fords, culvert crossings, or bridges needto be provided at live streams unless the streambedand approaches are firm and relatively stable. Culvertcrossings or bridges should be used sparingly. Theyshould not be used at all if the stream is prone toflooding. Maintenance of crossings and bridges ishigh. Debris can easily plug the entrance. Downstreamcavitation at the outlet can cause bank instability andeventual undermining of the culvert or bridge abut-ments. Damage to downstream areas caused by suc-cessive washouts of either abutment can also beexcessive. This can be avoided by providing a de-signed floodway channel that creates an island at theculvert or bridge during a flood. This is rarely done,however.



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Position lanes to most directly access the fields orpaddocks to be grazed, including crop or hay fieldsgrazed temporarily from time to time. Some lanes maybe temporary and be formed by two parallel singlestrand electrified fences. When lanes serve rotationalpastures, they should be positioned to create pad-docks that are as near square as possible. On verysteep ground, rectangular paddocks that have theirlong axis across the slope may be preferable if forageutilization becomes stratified from top to bottom ofthe slope. Placing lanes directly up and down steepslopes should be avoided if at all possible and still geta good paddock layout. If this is not possible, the laneshould be paved with an erosion resistant material,graded to have water diverters placed at regular inter-vals, or both. Equip any lane with long continuousgradients with water diverters to break up waterflowsdirected down the lane.

Width of the lanes is dependent upon the size of thelivestock, herd size, and expected equipment traffic.

The operator should keep lanes as small as they andtheir livestock feel comfortable with. Lanes tend tobecome unproductive grazing areas. Building wideones wastes the pasture resource.

Avoid driving equipment up and down unpaved lanes.Livestock use the slightest wheel rut as a preferredtrail. Continual use kills out the vegetation and causeserosion to begin where water can channel and gathervelocity in the trail. Some producers that need machin-ery access along laneways create a parallel accessway.This can be done by using a three-gate opening (fig.5–36) where each paddock division fence intersectswith the lane fence. This also cuts down on lane trafficby livestock because they can go from one paddock tothe next without setting hoof in the lane. It also allowseasy egress no matter which way direction of flowmust be out of the paddock.

Figure 5–36 Three-gate opening*

Electrifiedwire gate

Division fence

Livestockflow

Lane

Electrifiedwire gate

Equipmenttraffic

Equipmenttraffic

Right Wrong

To working area, barn, or milk parlor

Electrifiedwire gate Livestock

flow

Division fence

Lane

Equipmenttraffic

Equipmenttraffic

To working area, barn, or milk parlor

* Always position gates along lanes in the corner nearest next move. The three-gated opening labeled right can facilitate a moveup or down the lane shown. It also allows for equipment movement outside the cattle lane to avoid causing wheel track trailingin unpaved laneways.

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(h) Facilitating practice—Fencing

Fence layout and design require forward thinking. Thenumber of divisions and their size come from thepasture budget described in Accelerating practice—Prescribed grazing section of this chapter. This isdetermined by the productivity of the field beingsubdivided, the forage species growing there, thenumber of head being fed, their size and growth rateor milk flow, and the grazing period they will be on thepasture unit. Other questions to answered when plan-ning include:

• How much of the farm will be used for grazing?Annual production of pasture must be deter-mined. A realistic utilization rate must be set. Itmust match the livestock demand for forage forthe grazing season. If crop and hay fields are tobe used seasonally, the fence and lane layoutneed to provide easy access to them at pointsthat create the least amount of trailing or poach-ing damage. They need secure perimeter fences,access to water, and possibly temporary interiorfences to strip graze off forage.

• Will some of the pasture be machine harvested?If so, which portion is the best site for that activ-ity? This area will be best served with interiortemporary fences that can quickly be taken up toopen up a large area for harvest. This increasesmachine harvest efficiency. These same fenceswill also be easily replaced once machine harvestand any topdress fertilizing are complete.

Fencing, therefore, depends upon a whole farm foragebudget, which will be detailed in the section on Foragecrop production management. This budget integratesand allocates all the forage and feed resources that areproduced on the farm. Fencing facilitates this alloca-tion of the forage resource to livestock. With modern,light-weight, portable fencing materials, this becomesmuch easier to do than in the past when fencing, oncein place, was rarely moved.

Fencing materials are diverse. Woven wire, steelwelded panels, barbed wire, smooth high tensile wire,polywire, polytape, polymesh, board (plank or stock-ade), rail, chain link, steel rail or pipe, cable, concrete,stone, and plastic are all used. Each has their place.Woven wire, barbed wire, and smooth high tensilewire are good, economical fencing material for live-stock control along the perimeter of grazing areas.

Smooth high tensile should be electrified for bestcontrol. Wood board, rail, chain link, concrete, stone,and plastic can be also used for perimeter fencing, butare used for decorative, screening, or security reasonsas well as control. They tend to be expensive to installand maintain. Plastic fence is being used to replacewood board fences because they do not rot or requirerepainting. Fences in working areas where livestockare crowded and seeking ways to escape need strongmaterials. Heavy planking, steel rail or pipe, weldedpanels, and cable are often used. Stone and concretehave been used some for corrals and barnyards. Whenused, they must be sunk to a soil depth below the frostline.

The posts used to hang the fencing materials come indiverse materials and sizes as well. Post materials aretreated wood, untreated native wood, fiberglass,plastic, steel T-posts, angle iron, or pipe and rein-forced concrete. Wood and concrete posts are themost rigid and can handle high lateral loads withoutbending or breaking. Steel can bend under heavyloads. Plastic and fiberglass tend to get brittle with ageand can break under moderate loads. Sudden impactsare more likely to shatter them than when just beingleaned against.

The choice to use electric fence hinges depends on theability to provide electricity at the site convenientlyand reliably, the miles of fence to energize and main-tain, the permanency of the fence, the degree of con-trol that is needed or desired, and to a large extent, theinclination of the producer. Woven wire and barbedwire have served well for years. Their initial cost israther high compared to most electrified fences.However, with timely maintenance their degree ofcontrol is as good and they do not rely on an electricalshock that is often hard to consistently maintain tocontrol livestock. Some arguments have been raisedabout the longevity of woven and barbed wire com-pared to high tensile wire. However, in humid andsubhumid climates, the wood posts on which the fenceis suspended will rot off at ground level before orabout the time the wire fails. Steel T-posts longevity isgenerally in the same timeframe. New steel posts canbe seen in several old wire fences. Many soil types arehighly corrosive to steel. Pitting of the steel occurs atthe ground line within a few years and the posts even-tually break.



Chapter 5

Several guidelines should be followed to ensure thatelectric fences operate consistently all the time:

• Voltage must be maintained at all times foradequate livestock control. To achieve thisexacting standard requires a reliable charger orenergizer, first. Low impedance, high voltageenergizers meet this requirement. These energiz-ers produce a short, high energy pulse. This shortburst of high energy can be sent down a longlength of wire that may be partly grounded byweeds and still provide shocking power. Varioussizes are available and are selected based on theamount of fence to be charged. They are rated injoules or in miles of fence. Both ratings can bemisleading. The delivery of amperage that causesthe shock is dependent on the pulse rate as wellas the joule rating. If the pulse rate is slower, lessamperage is delivered down the wire and lessshock delivered as well. Miles of fence ratingsassume no brush, weeds, or grass clinging to thefence, nor inadequate grounding or poor insula-tion of the wires.

• Good insulators must be used to suspend thewire from all wood and steel posts, or noncon-ducting plastic or fiberglass posts used instead.

• The fence and charger must be properlygrounded.

• Lightning arrestors should be installed to protectenergizer from damage.

• Vegetation growth along the fence line must becontrolled. Sometimes, this is easily achievedwhere the livestock can graze under the lowestwire. They often preferentially graze these areasvery close.

• Maintain fence integrity, check for proper ten-sion and post damage.

• Surge protectors are important when served bypower line electricity.

Energy sources for electric fences can be regularfarmstead service lines or batteries, or it can be solaror wind powered units. Choice is dependent on thelength of fence, degree of reliability needed, cost,accessibility, and length of service needed.

All livestock need to be trained to respect electrifiedwire. This can be done at infancy if raised on the farmor ranch where electric fence is used. If new animalsare brought in, they should be trained in a confinedarea before being placed on pasture.

Regardless of whether a wire fence is electrified ornot, construction principles for them remain the same.Brace assemblies at the corners, gate openings, ends,and wire stretching points must be built to handle thestress placed on it by wire tension. If these are builtimproperly, the end and corner (anchor) posts willslowly pull out or the bracing will collapse, or both.Whenever possible, posts should be driven on perma-nent fences. If not driven, they must be backfilled andtamped well to remain solidly in place. Brace assem-blies should be placed at corners, at sharp breaks inslope, and at no more than 660 feet on straight runs tostretch wire (stretcher-post assemblies).

Curved fences built to follow land contours shouldhave stretcher-post assemblies in straight sections, notin the curve itself. Curved fences, whether in thevertical or horizontal plane, require posts with greatrigidity and must be set well to avoid tipping or bend-ing. If steel T-posts are used to save time and labor,wood posts should still be used and spaced at regularintervals between steel posts to alleviate some of thestrain.

Generally, posts of permanent fence brace assembliesshould be a minimum of 5 inches in diameter and 8feet long and buried at least 3.5 feet deep. In someplaces it may be necessary to drill into rock to get this.For light weight fences (single or double strand), shortruns of permanent fence under 330 feet long, andtemporary fences, an anchor post with a diagonalbrace set into the ground or on a brace block in thedirection of the pull is appropriate. The anchor postscan also be used in shallow soils when full post settingdepth cannot be achieved easily. Backfill over-widenanchor post hole with concrete. Allow concrete to setand cure before stretching fence on the assembly.

Always place fencing materials on perimeter fences onthe side where the livestock are most likely to bepushing on it. Stretch wires with wire stretchers builtfor the type of wire being used. There are severalmodels. Never use vehicles or tractors to stretch wireother than as a dead anchor. Board ends should abuton posts wide enough to accommodate double nailing.Fence heights, spacing of wire or boards, and meshopening must vary by the type and class of livestockbeing controlled. Type of fencing material is oftendictated by animal safety concerns. Wide meshedwoven wire and barbed wire can cause serious injury

Chapter 5



or death, but accidents also happen with other materi-als as well. Well-fed animals are less likely to testfences unless under duress.

Temporary division fences can be nothing more thanelectrified single or double strand wires suspended onshort, hand driven posts for most types of livestock,including sheep. These fences are quite portable andhave spurred renewed interest in rotational stocking.If mistakes are made in allocating forage to livestock,they can be easily corrected by repositioning thefences. These fences can either be rolled up on a spoolor collapsible so that wheeled vehicles, people, orlivestock can go over them when necessary. Theplastic posts often used to suspend the wire on theseportable fences come in many different designs. Someare downright unhandy and may cause inadvertentcontact with a live wire. Others are not very durableafter prolonged sun exposure. Some fiberglass rodssplinter and are nasty to handle barehanded.

All fences require checking and maintenance, espe-cially as they age. Fence wires can age more quickly ifcrimped by staples or fasteners at posts, abraded, ordamaged by the stretcher used to string it up. Woodshould be pressure treated to increase useful life.Plastic and fiberglass need an ultraviolet light (UV)protection formulation. Galvanized wire should becoated to class III specifications. Heavier gauge lastslonger than thinner gauge and has more strength. Thedifference in price is not worth the aggravation later.

Gates for ingress and egress also vary widely in thematerial used and strength. They may be simple onestrand electrified wire, electrified rod swinging gates,electrified spring wire with insulated handle, barbedwire suspended on two or three poles, tubular steel,board, plastic, woven wire suspended on a steel frame,chain link suspended on a steel frame, or weldedpanels on a frame. Cattle guards can be used at heavilyused gateways where livestock never need to walkthrough. Their use avoids continually opening andshutting gates. Gates need to be wide enough to passvehicles and livestock through without damage to thefence or the by-passers. Angle of approach and turningradius need to be taken into account to achieve properwidth.

Floodgates are used at points where fences must spancreeks and ditches. These too can be made of differentmaterials. They must be constructed to allow floodwa-

ter to pass through without their continual destruc-tion, not pull down sections of fence adjacent to them,and keep cattle from leaving the field via the creek orditch bed or bank. This is not always easy to do simul-taneously. Brace assemblies at these points must bebuilt extra strong, at least two brace posts plus theanchor post. These assemblies should be at least at topof bank and safely away from potential bank undercut-ting or protected with riprap. If the stream current isswift and passes a large volume of water by the flood-gate, the brace assemblies for the floodgate should bea separate set from the ones used to extend the fenceto the stream.

Swinging floodgates work well for nonelectrifiedfences. They can be suspended from cables attachedto the brace assemblies. Many different styles havebeen designed to lessen the collection of flotsam onthem. They should be buoyant so that they ride upwith the rising water.

On electrified fences, a single strand of high tensilewire or cable can span the stream or ditch. Regularlyspaced hot wires are suspended down to within a fewinches of the water or bank to keep livestock frompassing through. These are hard to take out unless thesuspended wire is too low or a large branch or treefloats by and snags it.

Floodgates will break away from time to time in majorstorms. To a certain extent, they should be designed todo that. Cables should be attached to J-bolts that hookon to O-bolts bolted into the anchor post, not wrappedaround anchor posts. When forces exceed tensilestrength of the bolts they straighten out and releasethe cable. This avoids major repairs to adjoiningfences or to the brace assemblies holding them. In-spect after every flood event to remove debris orrepair as needed.

Exclusionary fences can run from single strand electri-fied to permanent perimeter type fences. If streamcorridors are to be fenced, the simpler the fence is, thebetter it is in flood prone areas. From a maintenancestandpoint, a single strand electrified fence kept ashigh as possible and yet still get adequate animalcontrol is best. This limits debris buildup on the wire.A minimum of posts should be used to have the leastnumber of debris collection points and still suspendthe wire adequately. Setbacks from open water shouldprovide at least a 15-foot grass vegetative filter. The



Chapter 5

filter takes out most suspended sediment and somedissolved nutrients. Fences around woodlots shouldnot be built using the trees at the edge for posts.Hardware becomes imbedded in the logs and is thebane of loggers and millers.

(i) Accelerating and facilitatingpractice—Pasture clipping

This practice is a bit of both, accelerating and facilitat-ing. It stimulates forage regrowth by cutting off repro-ductive stems from forages. This causes new vegeta-tive shoots to appear. Pasture clipping can be used toget rid of competing vegetation or reduce canopyshade to favor forage growth. This makes it an acceler-ating practice. It also influences the movement ofgrazing animals by removing undesirable patches ofundergrazed forages. It can be used to change thepattern of spot grazing. This makes it a facilitatingpractice. This practice can largely be avoided if theutilization rate is kept high. It is far better to grazefewer acres and machine harvest the rest than to grazea larger acreage and then sacrifice leftover forage byclipping.

Pasture clipping can also be used as a weed and brushcontrol practice where the livestock mix does notcontrol the species invading or existing on the site.Although goats and sheep often eat plants that cattlewill not, mixed species grazing rarely happens oncommercial farms and ranches. Clipping does notimmediately control weeds or brush, but repetitivecuttings just before flowering prevents further seedingof weeds. Clipping does not eradicate or even providevery good control of rhizomatous or stoloniferousperennials. It controls annuals provided they aremown off before flowering. Some weeds not eaten bylivestock when green, once cut, are eaten because asthe weeds dry, their sugar content is enhanced. Clip-ping is appropriate on new seedings where livestockcontrol of weeds could damage young seedlings bytrampling or uprooting. Weeds should be clipped oftenabove forage seedling height to keep amount of clip-ping residue down. Too much residue can smotherseedlings.

Removal of seedheads and other tall vegetation mayalso improve livestock health. Fewer eye infectionsoccur if the irritants and disease transmitters areremoved.

Clipping can improve forage species mix if certainaggressive established species shade other species’seedlings coming up through the canopy. Clippingavoids the need of waiting for sufficient regrowth toproduce a hay or silage crop. This may often take toolong or be untimely, and cause shaded seedlings to die.There also may simply be too many acres to grazedown to the height needed to release the seedlings.

Rotary mowers work best in pasture setting. Dutyrating of mowers is important. Woody species requireheavier duty mowers. Pastures can be mown whilelivestock are present. Almost everything mowed willbe eaten. In rotational pastures, mow rejected areasafter the livestock leave. This tends to make the re-jected areas more acceptable next time, at least, theurine areas.

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600.0506 Managing foragecropland

Hayland and cropland produce machine harvestedforage primarily, but are often used as sources ofsupplemental, emergency, and seasonal pasture. Onsome farms forage crops have totally supplantedpasture as a source of feed for forage consuminglivestock. These farms have gone to total confinement.The livestock may not always be in freestall barns,barnyards, or feedlots. Milk cows may also be placedin loafing areas on dairy farms. Loafing areas areadjacent to the milking parlor and barn. Farmsteadssited along creek and river bottoms often locate loaf-ing areas in riparian areas to avoid using tillable acres.Other dairy farms only use pasture for youngstock anddry cows on any marginal land not fit to crop. Theseareas are not very productive and often are highlyerosive.

The movement away from pasture production toforage crop production, particularly with dairy farms,was partly caused by the perception that pasture wasan inferior forage production option. USDA Miscella-neous Publication 194, A Pasture Handbook, in 1946stated that closely grazed pasture "produces aboutthree-fourths as much digestible nutrients as the hay."In terms of dry matter it states, "Closely grazed pastureproduces about two-thirds as much dry matter as thesame plants would produce if they were allowed togrow nearly to maturity and then cut for hay." Thisbasic set of premises has been used repeatedly indifferent wording for the last 50 years. The samemisleading premises stay even with the differentwording.

First, closely grazed continuous pastures have a poorgrowth rate. They are kept at the low end of sigmoidcurve displayed in figures 5–20(c) and 5–25. We canagree that this is common practice and happens onmany pastures. However, with better grazing manage-ment, we can keep forages growing in the rapidgrowth rate range. The tighter the management, themore this can be maximized. In fact, it can be moreeasily done on pasture than on hay cropland. Haycrops are allowed to mature and end up on the slowgrowth upper end of the sigmoid curve.

Then, some authors begin to talk about hay and theideal premise is brought out, not the common practice.The same producers that are overgrazing pasturesprobably are not cutting their hay at peak qualityeither. Much hay is not harvested at the nearly tomaturity stage, but at advanced maturity stages. Alarge percentage of it is also damaged by rain, humid-ity, and sun exposure. Then it sits in storage and losesdry matter. Equally well managed pasture and haycropland will produce the same amount of digestibledry matter at the time of feeding. Both leave stubble inthe field. Livestock avoid some forage above thegrazing height. Preserved forage, whether it be hay orensilage, also leaves harvestable material behind. Thematerial includes leaf shatter, respiration losses,leaching losses if rained on, fermentation losses ifensiled, spoilage, and feeding losses. The end result, asshown in figure 5–37, is somewhere around a 20 per-cent loss of harvestable digestible dry matter even ifthe stored forage crop is handled right.

(a) Forage crop production

Forage crop production is capital, labor, and machin-ery intensive. It requires silage storage, dry hay stor-age, sometimes automated feeding systems, a full lineof machinery from seedbed preparation to harvest,feeding operations, waste handling, and often live-stock confinement facilities.

Forage crop production is approached in two basicways. One avenue is used to support pasture produc-tion. In this approach to grassland farming, foragecrops are only produced to carry the livestock throughperiods when pasture is dormant or in low supply.With this approach, the balance between pasture andforage crop production shifts from time to time de-pending on pasture availability and which is mosteconomical to produce and feed.

The other avenue totally supplants pasture production.This is often done to achieve economy of scale. Farmswith large herds and a low land-to-livestock ratio findthis most convenient. They may import varyingamounts of feed to the point of being totally depen-dent on purchased feed.

Whichever avenue the producer chooses, managementof forage crop production remains essentially thesame. The goal is to efficiently produce high quality



Chapter 5

Figure 5–37 Amount of dry matter loss of harvested forages during harvest operations and storage* (from Barnes, et al. 1995)

080 70 60 50 40 30 20 10

10

20

30

40

50

0

10

20

30

40

50

Storage loss

Harvest loss

DM

lo

ss (

percen

t)

Moisture when harvested (percent)

Direct cutsilage

Wilted silage

Preservativetreated hay

Field curedhay

* This is the loss of harvestable forage. It does not include stubble left below the cutter bar.

forages to the maximum potential of the site andefficiently convert it into a salable livestock product.

The remainder of this section focuses on the firstavenue of approach to forage crop production. Itrequires the highest degree of integration of all grazingland resources on the farm or ranch. To integrate wellrequires analyzing the farm or ranch operation avail-able resources, the tools that are available to produceforages, and how those tools can be used to bestadvantage on the specific site being analyzed. Thisthought and decisionmaking process is diagrammed infigure 5–38.

After integrating pasture and forage crop productionacres into a workable plan for the farm or ranch, theforages that will meet the landowners or manager'sobjectives need to be more closely analyzed. Thefollowing questions should be answered:

• Which forages are adapted to the climate andsoils on the land unit?

• What is the seasonal distribution of pasture now?• What could it be if we selected different species

from the ones currently growing on the farm?• Can the grazing season be extended past the

current one being used and not hurt the pastureresource?

• Once reasonable alternatives to feed the live-stock with pasture are exhausted, what forageswill meet stored feed quality and quantity re-quirements?

• What cultivars are appropriate for disease, in-sect, and soil reaction, salinity, and drainagecircumstance?

The thought process required for forage managementis shown in figure 5–39. Forage management planningstarts with gathering information on the site character-istics of each field. The climate and soil limitationsmust first be known. Forage suitability groups charac-terize major soil limitations and give guidance on howthey can be overcome. They help site selection by

Chapter 5



Figure 5–38 Forage integration model* (adapted from Barnes, et al. 1995)

Summarize each field by land use,soil type, fertility, pH, crop rotation,est. yields, seasonal grazing availa-bility, forage species/mix-condition,and cropping limitations.

Describe storage facilities by typeand digestible dry matter (DDM)holding capacity.

Estimate animal days on grazable pasture and when fed stored foragefor year. Estimate level of concen-trate feeding and calculate forageDDM requirements for both.

Summarize expected yields fromall fields. Account for foragecrop harvest losses and pastureutilization rates to avoid over-estimating forage production.

Develop alternatives to maximize use of the above resources. Consider all options for meeting forage DDMrequirements using at least-cost analysis and these influences: accessibility, access to water, fencing needs,equipment needs, crop rotation fit, seasonal forage shortfalls, and livestock enterprise mix. Plan crop rotationfuture years out.

Add up total estimated yields of pasture and stored forages based on each alternative's mix of pasture andforage crop acres and compare to present and future (?) animal requirements. Make a first cut of alternatives.

Evaluate remaining alternatives based onimpact to farm operations.

Select best-fit plan based on farm goals, affordability, and theability of the farm labor force to implement and maintain thealternative's measures.

Select contingency plans for weather events, crop failures, herdhealth problems, labor shortages, changing markets.

Develop a conservation plan.

Evaluate practice and equipment needsfor each remaining alternative.

Adjust capacities for actual andpotential refilling strategies and storage losses. Select storagefacilities based on cropping limitations and quality needs.

Summarize total DDM needs byanimal type and class. Calculatequantities needed of differentquality forage.

Forage Storage Animal

* The objective is to match the quantity and quality of forage available as pasture or stored forage with the requirements of specific livestockclasses and with the available or potential grazing and storage options.



Chapter 5

pointing out which forage species are suitable for thesoils on a land unit.

Forage species selection also involves selecting spe-cies readily consumed by the livestock type and classbeing raised on the land unit. They must be palatableand encourage maximum intake for high productionanimals. Other classes of livestock are often betterserved nutritionally by lower quality forage. Pastureand stored forage needs must be planned for theselivestock classes too.

Within species, there may be only one or two cultivars(varieties) or several to choose from. Specific cultivarsare selected for several reasons. Some are resistant toinsect and disease pests. Some are bred to be lower inor free of anti-quality factors, such as alkaloids,tannins, and saponins. Tall fescue is a good example. Ithas several cultivars that are endophyte free. Beingendophyte free allows cattle to graze it without thesymptoms of fescue foot, bovine fat necrosis, andfescue toxicosis appearing. Some cultivars are justmore productive. Others are bred to be leafier. Someforage species are bred to have a wide range of climatespecific cultivars. Alfalfa is good example of this. Ithas varieties that can withstand severe winters andothers that grow during the winter in warmer climatesby varying the degree of fall dormancy each one exhib-its. Other forages are bred to be higher in protein orlower in fiber.

Forage selection is also done to choose betweendistinctly pasture type forages and hay type forages. Atother times forages may be selected that harvest orgraze well. For example, orchardgrass and bermuda-grass produce good pasture or hay. Some species,such as alfalfa and birdsfoot trefoil, have hay typecultivars and pasture type cultivars. Some grasses canbe grazed, but do better as hay crops. Examples of thisare timothy and smooth bromegrass. They elevatetheir growing points early and have basal buds that donot break dormancy until around heading time. Ifgrazed or cut before boot stage, they are slow torecover. When mixed with alfalfa and cut early at budstage for alfalfa, both grasses can be weakened andwith successive harvests, die out prematurely.

Once the production options have been weighed andthe best fit plan for the land unit is selected, it is timeto implement forage crop management. This willensure the right kind of stored forages will be avail-able to round out the livestock feed ration.

Chapter 5



Figure 5–39 Forage management planning elements and how they interact with one another (from Barnes, et al. 1995)

is altered by

Storage

Forage management

Cultivarselection

Speciesselection

Foragequality

Animal foragerequirements

Harvest/grazingmanagement

Stand life(species with regrowth potential)

Forageyield

Control of pestsand/or

anti-quality components

Siteselection

Nutrient/manure

management

Crop rotationplan

starts with

for

for

for maxim

um for maximum

followedby

increases

increases

influences

influences

influences

influences

influencesinfluences

influences

to match

controlledby

controlledby

is altered by

determinesmaximum

interacts with interacts with

influences



Chapter 5

600.0507 Vegetative con-servation practices forforage cropland

(a) Harvest management practice—Forage harvest management

This practice is used to provide forages of varyingquality in the quantities needed for a livestock enter-prise. Forages are stored to meet all or part of theforage needs of livestock. Stored forages may be fed tosupplement pasture and to increase dry matter andfiber intake, especially with dairy herds. Duringdroughts and other emergencies, stored feed maycarry livestock through until there is pasture to grazeagain. Other times, stored forage is stockpiled toprovide feed during expected loss of pastures, such asin winter.

Depending on the quantities needed of each foragequality, forage harvest can be timed to produce theproper quality for the livestock class being fed. As aforage reaches maturity, it becomes more fibrous anddecreases in protein content. This lower quality forageis still appropriate for many classes of livestock. Forexample, in figure 5–40 relative feed value (RFV) is anindex that ranks forages relative to the digestible drymatter intake of full bloom alfalfa (RFV = 100). For

dairy cattle, RFV equals DDM times DMI divided by1.29. Digestible dry matter (DDM) is calculated as 88.9minus 0.779 times percent acid detergent fiber (ADF),and dry matter intake (DMI) is calculated as 120 di-vided by percent neutral detergent fiber (NDF).

Forage harvest management as it pertains to perennialforages becomes more difficult. While keeping in mindthe livestock needs, the land manager must alsoweight what is best for the forage resource, and ulti-mately their costs of production. For perennial for-ages, it becomes a compromise between yield, quality,and persistence. More harvests per season meanyounger vegetation is being cut so quality is high, lowfiber and high protein content. However, this can leadto stand loss and the need to replant or rotate toanother crop. Fewer harvests per season will bettermaintain stand persistence, but forage cut will bemore mature and so quality, or its digestibility, will beless. The forage will be more fibrous and lower inprotein.

Most forage stage of maturity guidelines put out acrossthe Nation are a compromise between quality andstand life. Harvesting a little earlier would improvequality, but reduce stand life if done continually.Harvesting a little later lowers quality, but builds foodreserves, allows basal buds of some species to breakdormancy, and increases stand life. More frequentharvests tend to decrease overall dry matter yieldespecially from a multiple year standpoint. This is aresult of lost vigor and slowness to recover betweencuttings. This leads to a progressive and quicker standdecline on a year-to-year basis.

When grasses and legumes are grown together, thelegume stage of maturity is used to time the harvestexcept in the case of birdsfoot trefoil, Ladino clover,and white clover. Some grass species have had culti-vars selected that seek to time their stage of maturitywith that of alfalfa. For instance, orchardgrass variet-ies have been selected to slow down spring matura-tion. Meanwhile, timothy and smooth bromegrassvarieties were selected that sped up their first cutmaturation to coincide with that of alfalfa. The twowhite clovers and trefoil tend to maintain their qualitybecause they are indeterminate in their growth. In thecase of common white clover, it is too diminutive tomake up much of the total forage taken off a mixedstand anyway. Therefore, the grass component’s stageof maturity is a better target to get the forage quality

Figure 5–40 Relative feed value and livestock classes(adapted from Barnes, et al. 1995)

Heifer, 12-18 mo.;beef cow with calf

ewe with lambmare with foal

Dairy, last 200 days;heifer, 3-12 mo.stocker cattle

Dairy, 1sttrimester; dairy,calf, lambs,colts, and fillies

Heifer, 18-24 mo.;dry cow or ewe

horses - light duty

100 110 120Relative feed value

130 140 150

Chapter 5



desired. Common white clover is also not likely topersist in a stand managed only for hay. The grasscomponent shades out common white clover unless itoccupies areas lacking grass cover.

Annual grass forages, such as sorghum, millet, andsudangrass, that can be harvested several times in aseason, should be cut at boot to early head stage. Thistriggers more tiller growth at their bases because theyare not able to set seed. If a foliar or insect outbreakthreatens stand survival or forage quality unduly,harvest prior to correct stage of maturity. This willpreserve as much quality as possible and remove thehost to curtail spread of the pest. For instance, mowalfalfa within 10 days of normal stage of maturitywhen economic threshold is exceeded for weevils,spittlebugs, or potato leafhopper. When the economicthreshold is exceeded for alfalfa caterpillars, harvestforage at early bud stage. In some cases outbreaksoccur too early after the previous harvest. The appro-priate labeled pesticide must then be used to preventloss of a forage cutting or the whole crop.

For annual forages that are harvested one time only,the whole focus can be on achieving the desired foragequality for livestock consumption. This may be tem-pered a bit on silage crops where the type of storagebeing used has an influence on the amount of moistureleft in the forage at filling time. However, somethought about the quality of the forage needed shouldplay a role in the type of silo built. Bunker silos, al-though cheaper to build per cubic foot of storage thanupright silos, require more moisture in the silage toensure good compaction. The same is true for baggedsilage.

Compaction of the silage is needed to have goodanaerobic fermentation of the silage. The upright silosachieve the compaction just by the sheer weight of thematerial stacked 50 to 80 feet high. With more mois-ture in the silage this can lead to leaching losses of drymatter and create a high biochemical oxygen demand(BOD) effluent. This effluent must be diluted substan-tially to not cause a fast drop in oxygen levels ofreceiving water. Effluent production generally occursin forages that are ensiled in bunkers or bags at mois-ture contents over 70 percent or in tower silosatmoisture contents above 65 percent. The percentmoisture values shown in table 5–6 are the recom-mended moisture levels for hay-crop and corn silage toensure good fermentation and a well-preserved silage.

Corn silage chopped at the dent stage of kernel matu-rity coincides pretty well with the upper limit of mois-ture of 68 percent. If kernel maturity proceeds to theblack layer stage, then the whole plant moisture levelis down to the lower limit of 55 percent. Harvestshould not be delayed past black layer. For bunkerand conventional upright silos, harvesting at the one-third milk line is appropriate. At one-half milk line, themoisture is appropriate for oxygen-limited silos. Forsorghum, chop when kernels are between soft tomedium dough stage.

In many parts of the Nation wet weather and highhumidity also impact when, how, and at what moisturecontent forage crops can be harvested. In some situa-tions where rains come on a daily basis, hay-crops thatare reaching maturity should come off as direct cutsilages to preserve as much quality as possible. Efflu-ent production will need containment. The addition ofdry feedstuffs, such as ground ear corn, reduces theoverall moisture content and acts to soak up theleachate produced before it becomes effluent.Proprionic acid and similar organic acids can also beused. They quickly drop the pH of the silage to avoidbad fermentation from taking place. This reduceseffluent production. However, some effluent produc-tion still occurs that needs containment and treatmentas part of a waste management system for the landunit. This is far better than letting a valuable forage

Table 5–6 Silage storage structure forage moisturesuitability

Storage structure type Hay-crop 1/ Corn 2/

(% moisture) (% moisture)

Upright or tower, 60 – 65 63 – 68conventional

Upright or tower, 40 – 55 55 – 60oxygen – limiting

Bunker or horizontal 65 – 70 65 – 70

Bag silo (plastic tube) 50 – 60 65 – 70

Balage (plastic wrapped 50 – 60 ––– round bales)

1/ Coastal bermudagrass should be ensiled direct cut (65 to 75%) toget required packing.

2/ Add 5 percentage points to the range for sorghum silage.



Chapter 5

resource be underused when it cannot be grazed offfast enough to keep up with production. It is alsobetter than waiting for dry weather to make hay. Muchof the forage will rot, and the rest is a mix ofovermature and highly weathered first growth andgreen second growth material.

In other areas storm systems track through on a 3- to4-day schedule. This prevents field cured hay that isnot rained on at least once from being producedwithout preservatives. Where relative humidity levelsare high as well, this becomes even harder. In theseareas wilted silage or haylage can generally be takenoff the fields before the next storm system arrives.

For the harvest of legumes and legume-grass mixtures,roller conditioners are used universally to crack thestems of the legumes. This speeds up drying. Flailconditioners can be used on grasses to break the waxycuticle and their stems to speed drying. These condi-tioners tend to break off too many leaves on legumes.Both conditioners are generally integrated with andmounted behind a mower unit. The combined imple-ment is called a mower-conditioner. Later on, duringdrier weather when rains are infrequent, cuttings canbe made as dry hay. This basically is taking what theclimatic conditions are allowing. For many farms, thisis not a large increase in equipment. On some, it maymean having a forage harvester and a forage wagon ortwo as well as a baler. For others that have a forageharvester for corn silage, the purchase of windrowhead for the forage harvester is all that is required. Theadded expense can easily be paid for in the degree offlexibility it affords to harvest more quality forage in atimely fashion.

Another option is to bale dry hay using preservativesthat are sprayed on when mowed or baled. This allowsthe hay to be baled at higher moisture levels (between25 and 35 percent moisture) and can reduce dryingtime by 1 day. Preservatives used range widely fromproprionic acid and other organic acids to anhydrousammonia to bacterial inoculants. All have their draw-backs. The acids are corrosive to farm implements.Anhydrous ammonia is an excellent preservative andprovides nonprotein N for the livestock feed ration.However, it can be toxic when fed to livestock ifinjected at rates above 3 percent of forage weight. Thebacterial inoculants seem to only improve appearance,but do little to reduce dry matter losses of stored hay.

Another harvest method that works well in wet cli-mates is green chopping. Fresh forage is chopped dailyto feed directly to livestock on a feedlot or loafingarea. Traditionally, this is used in dairy country. Obvi-ously, this eliminates the need for pasture for thatgroup of animals, but it does not eliminate the need topreserve some forage for later use unless it is pro-duced off the farm. Although used widely when firstintroduced, little green chopping is done nationwidetoday. It is labor and machinery intensive, although ittends to use the forage harvesting equipment to themaximum. However, a separate flail chopper is gener-ally used instead of the conventional forage harvester.It takes a good manager to use this method well.Average management leads to a wide spread in stageof maturity of the harvested forage. Early cuttings arecut too early for maximum stand survival, and latecuttings are overmature for the best nutritional valueto milk cow herds. This variation in quality and itsinterference with other crop harvest activities ondiversified farms led to its loss of popularity. The flailchopper also causes a ragged cut that retards regrowthand lowers stand persistence. Green chopping doeshave a place on farms where the land base is small inrelation to livestock numbers. It optimizes forageproduction per acre. All that is left behind is somestubble. The most common forage grown for greenchop is alfalfa.

Moisture content of forages when being windrowed,tedded, or inverted should be moist enough to keepleaf loss to a minimum. In humid areas field dried haymay need to be rearranged on the field a few times toget all the forage to dry evenly. Tedders and invertersare used to expose underlying forage to the sun andwind. This is especially important where the ground isdamp from previous rains. Tedders or inverters shouldstir or lift the forage while it is still over 40 percentmoisture. The hay when raked for baler pickup shouldbe between 30 and 40 percent moisture.

Bale field cured hay at 15 to 20 percent moisture toprevent heating and spoilage in the barn or stack. Thisminimizes dry matter losses and prevents spontaneouscombustion from occurring. Bale hay to be forced-airdried at 20 to 35 percent moisture. This hay is gener-ally treated with a preservative and stacked on palletsin a building with an air circulation system.

Chapter 5



Number of cuts or harvest interval of perennial foragecrops is also a compromise between yield, quality, andpersistence. This is because it is tied closely to stageof maturity of the forages. However, this is not alwaysthe case in grasses. Many grasses are only reproduc-tive once a year. Once they have produced seedheads,the rest of the tillers sent up are vegetative the rest ofthe growing season. Therefore, stage of maturity ismeaningful only once a year. The harvest interval afterthat time is arbitrary, being based on harvesting conve-nience, the legume component’s maturity, and weatherdelays. Some forage cultivars have been bred to take amore intense harvest schedule than others.

If high quality forage is a goal, then the number of cutswill be maximized for the climate. The crop rotationplanned for such a goal must be a more rapid one. Itinvolves a quick replacement of the forage crop withother crops in the rotation unless the forage cultivar isup to the stress. On fields in continuous perennialforage crop production, more frequent hay seedingsare necessary if the forage cultivar cannot take fre-quent cuttings.

If maximizing the number of cuts is a goal, then it isnecessary in humid climates to be able to ensile aswell as make dry hay. For producers with round bal-ers, this may require nothing more than the ability towrap large round bales in plastic to create balage.

End of growing season harvest interval in areas wherewinter survival of forage crops is a concern should beat least 40 days long for legumes and at least 30 daysfor grasses. This allows food reserves to be replen-ished before going into winter. The last cut should betimed to coincide with a killing frost if the forage isneeded for stored feed. On fields that can be pastured,the last cut could be 30 to 40 days before a killingfrost, and then the pasture should be grazed after thekilling frost to extend the grazing season. In eithercase a nonharvest period before a killing frost is bestfor long-term forage stand survival. Some evaluation ofthe stand condition is necessary, as well, to decidewhether to harvest any of the forage produced duringthe fall recovery period. Leaving unharvested after-math may increase forage stand survival significantlydepending on the severity of the winter and the vigorof the stand going into the winter. The aftermath canbe left to provide soil insulation and cover for wildlife.

In snowfall areas, it will trap snow better than shortstubble. This provides additional insulation and im-proves soil moisture distribution across the field in thespring. The added insulation can reduce the chancesof frost heave damage as well as winter killing.

Stubble height must be based on each species’ require-ment for adequate residual leaf area; adequate num-bers of terminal, basal, or axillary tillers or buds;insulation from extreme heat or cold; and unseveredstem bases that store food reserves needed for a full,vigorous recovery. Where mixed stands are raised, thespecies grown together should have similar stubbleheight requirements. Always go for the stubble heightof the species requiring the highest stubble. This keepsthe least tolerant or most sensitive forage in the stand.Some loss of yield may occur, but the quality of theforage taken off will be higher. There will be less basalstem that is mostly lignified fiber. For annual forageswith regrowth potential, sufficient stubble height (6 to8 inches) must be left behind to promote tillering.Thicker stalked cultivars need higher stubble heightsthan thin stalked ones to tiller well.

In special situations, stubble heights may be reducedbelow that generally used to promote fast regrowthand plant vigor. In the South, alfalfa should be closemown at last cutting at the end of the growing seasonto control alfalfa weevils. This removes their overwin-tering cover. Mow warm-season grasses grown inassociation with winter annual legumes or grassesclose at last cutting to release emerging seedlings.

Contaminant effects on forage quality are as equallyimportant to consider as the nutritive components.

Green chopping of sorghum-sudangrass and pipersudangrass must be done with care to avoid prussicacid (hydrocyanic acid) poisoning. The risk of this isreduced if sorghum-sudangrass is cut when over 30inches tall and piper sudangrass when over 18 inchestall. Drought or frost damaged forage of these speciesshould be avoided for at least a week after the eventhas ceased. Ensiling actually reduces prussic acidcontent during fermentation and lowers it below toxiclevels (<200 ppm) sufficiently in 6 to 8 weeks. Theseforages, including sorghum, are poisonous to horsesand are not to be fed.



Chapter 5

Forages containing high levels of nitrates (>1,000ppm) are also better harvested as ensilage than as hay.No loss of nitrates occurs during hay curing. Haylageas it is fermenting reduces nitrates to nitrogen dioxide,silage gas. This detoxifies the haylage, but the gas cancause severe lung damage within seconds of exposureif not vented out of the haylage stack or silo. Carbondioxide is also formed during fermentation. It isheavier than oxygen and can displace it in the silo.People have died from suffocation not realizing soonenough that no oxygen remained in the silo. Corn orsorghum fertilized heavily with nitrogen and stressedby drought can also have high nitrate levels. Siloscontaining forages suspected of being high in nitratesor silo rooms attached to them should not be enteredfor the first time within a week of filling without beingthoroughly ventilated first. Delay feeding silage for 6to 8 weeks after filling.

High tannin forages, such as birdsfoot trefoil andsericea lespedeza, lose as much as half of the tanninduring field drying. In doing so, digestibility increasessignificantly.

Blister beetle poisoning of horses can occur where thebeetles occur in high concentrations in isolated spotsof alfalfa fields that are mechanically conditioned.They contain a toxic compound called cantharidin thatis released into the hay when they are crushed withthe hay in the conditioner rollers. The compound isstable in hay and therefore can be harmful to horseseating the hay.

Red clover hay infected with black patch funguscontains an alkaloid, slaframine, that sickens livestockwhen fed shortly after storage. Long-term storagereduces the concentration.

The alkaloids produced in endophyte infected tallfescue are reduced only 20 percent in curing hay andlittle at all in storage. Ensiling has little effect.

Moldy hay causes colic and heaves in horses. Cattlecan have mycotic abortions or contract aspergillosisfrom certain fungi associated with moldy hay.

Fields should be free of metal, such as wire, to preventhardware disease in livestock.

Another forage quality issue is the length of cut ofensiled forages that are chopped. The theoretical

length of cut range for hay-crop, corn, sorghum, andsmall grain silages is 3/8 to 3/4 inch. This is done bysetting the shear-plate on the forage harvester for a 3/8to 3/4 inch cut. This is theoretical because not allparticles will be in that size range. About 20 percentactually should be longer than 1 inch to provideenough long fibers to aid rumen digestion. Choppingthe forage fine aids in compaction so that good fer-mentation takes place. Again, some compromise mustbe reached. Too fine is not good for rumen digestion,but too long does not allow for good compaction.

Storage of the forage is important to maintain qualityand digestible dry matter. Whenever possible, dry hayor silage should be under cover in humid climates.This can be nothing more than plastic film. Largeround bales left on the ground and uncovered can loseup to 40 percent of their dry weight in humid climatesover a season. Losses range from a low 0.5 percent permonth in arid climates to as high as 3 percent permonth in wet, warm climates. Moldy hay is oftenrejected by animals unless forced to eat it. Then, theycan have health problems as mentioned earlier. If largeround bales are made to save on labor, they musteither be wrapped with plastic around their circumfer-ences or placed on end in a barn or shed in humidareas. They can be stacked three high without any-thing more than a front end loader on a tractor.

Bunker silos must be covered to prevent great spoilageand leaching losses. Plastic film weighted down toprevent uplift and removal is necessary. If this is notdone, leaching losses can be high as rain filters downthrough the material. If exposed to the air, spoilage ofthe top foot or two is common in humid areas. Drymatter is lost (up to 25 percent of it), and the spoiledforage will be rejected at the bunk.

When haylage or silage is bagged, care must be takenin their handling and placement not to puncture or ripthe plastic. They also must be checked weekly forrodent or raccoon damage and patched. If manage-ment is lax, spoilage will start at these openings andspread farther into the bag. Silage should never bestacked except under limited and very temporarycircumstances. Effluent can readily escape, contami-nating shallow aquifers or adjacent streams. Drymatter losses can be high, from 15 to 30 percent of thetotal placed in the stack. Hay, if stacked outdoors,should be covered and placed on a well-drained pad oron pallets.

Chapter 5



(b) Accelerating practice—Nutri-ent management

Nutrient management on forage crops differs frompasture nutrient management in that it is a put-and-take operation. When harvested all the nutrients in theforage are removed from the field. They may be re-placed later, or they may not. On land units wheremanure is recoverable from a feedlot, barn, or barn-yard, it can be returned to the field. The likelihood of itcoming back with the same proportions of nutrients asleft the site is nil. If fed to livestock while on pasture,there is no way to recover the nutrients economically.There is a total transfer of nutrients from the foragecropland to the pasture. Therefore, chemical fertilizersare used to provide the balance of nutrients needed tocontinue optimal production if so desired. Legumescan be used to provide some or all of the nitrogen (N)needed to support optimal grass production. However,the removal of phosphorus (P), potassium (K), andsecondary nutrients from forage crop production landsby harvest activities must still be dealt with.

Forage crop response to fertilizer additions is depen-dent on the inherent productivity of the soil in whichthe crop is growing. Forage production in humidclimates is mainly controlled by available water hold-ing capacity (AWC). The next most important soilfactor is soil reaction. In more arid climates, it iscontrolled primarily by rainfall or irrigation rates andsalinity or sodicity. These factors set the maximumforage production limit, not fertilizer. In figure 5–38,note site selection does determine maximum yield.Each soil series has a response curve to nutrientadditions. Some of them may be similar. Soil seriesgrouped together as forage suitability groups shouldhave the same response curve. Figure 5–41 shows twosoil groups and their response curves to fertilizer.Fertilizer merely drives the soils to produce near theirpotential maximum when weather and pests permit.

The maximum potential yield is seldom achieved on asite. It certainly is not achieved from fertilizer addi-tions. The economics of fertilizer additions dictatesthat this is not going to occur under commercialforage crop production. Before the maximum potentialforage yield can be reached, each increment of fertil-izer used costs more than the worth of the forageproduced. This is illustrated in figure 5–42. Going from100 pounds of fertilizer per acre to 150 pounds offertilizer per acre produces a good crop response. The

additional forage produced is worth more than thecost of the additional 50 pounds of fertilizer. However,at the 150 pounds per acre rate, the cost of the lastpound of fertilizer equaled the value of the forageproduced. The yield at which this occurs is called themaximum economic yield. This yield is not static, butchanges with the cost of fertilizer and the value of theforage crop being produced. The maximum economicyield is going to occur at a much lower application rateof fertilizer on a low response forage suitability groupsoil than on a high response forage suitability groupsoil. Compare where the rates of fertilizer intersect thetwo response curves shown in figure 5–41.

Because forage crop production removes nutrientscompletely from the field, the primary goal of nutrientmanagement on these lands is to return nutrients backin nearly the same proportion as were removed. This istempered by the natural fertility of the soils being usedto produce forage crops. In some parts of the Nation,native fertility can be high in P or K, or both. Long-term forage crop production may do little to reducethe natural store of these nutrients. Little or no cropresponse occurs when fertilizers containing these twonutrients are applied on soils where they are abun-dantly available. In other areas these nutrients may

Figure 5–41 Response to fertilizer by two foragesuitability groups*

High response forage suitability group(high AWC, pH of 6-7, etc.)

Low response forage suitability group(low AWC, pH, etc.)

Yie

ld

Quantities of fertilizer in lb/acre

20 40 60 80 100

* The same amount of fertilizer applied resulted in two verydifferent forage yields. In the case of the low response foragesuitability group, water was primarily the limiting nutrient.



Chapter 5

Figure 5–42 Maximum economic yield* (adapted fromBlackmore 1958)

Yie

ld

Do

llars

100 150 200 0Yb

Last increment of yieldvalue equals input cost

Point of maximum

economic yield

Responsecurve

Cost offertilizer

Quantities of fertilizer in lb/acre

Yb=Base forage yield without fertilizer

* Maximum economic yield is the point on response curve wherean additional dollar spent on fertilizer returns a dollar of addi-tional forage produced. Beyond that point the additional fertil-izer being spread on the field costs more than the additionalincrease in forage production is worth.

have always been deficient or marginal. Any cropproduction quickly draws down the natural store of Pand K. Yields quickly drop, and forage stands becomeweak and thin. In these areas P and K are added toreplace those removed by harvest (maintenance appli-cations). Additional P and K may be added to build thesoil store of P and K. This latter amount of fertilizer iscalled build-up or corrective fertilizer applications.This is done so that the two nutrients do not limitproduction. Once a soil test indicates that they are inthe optimum range, no further build-up or correctiveamounts is recommended. Only maintenance amountsare recommended, generally based on a projectedyield of the next crop. A more conservative approach,however, would be to replace what was taken off bythe previous crop. This is truly replacement; the termused to describe this method of nutrient management.Since no response is supposed to occur when the soilis in the optimum range, being theoretically short afew pounds of P and K should not jeopardize a betterharvest than the year before. Furthermore, it avoidsover-applying fertilizer based on a prediction that is

more likely to be missed by a wider margin than aharvested yield based on less than ideal estimates ofdry matter.

Forage crops remove large amounts of K, 30 to 50pounds K20 per acre for every ton of forage harvested.Grasses are better at taking up K than are legumes.Grasses have a fibrous root system with a high degreeof root replacement. Legumes are primarily tap rooted,have fewer roots, and a slow root turnover rate. Thegrasses with their greater, ever-shifting root mass canexploit the soil better for nutrients than legumes.Some grasses, such as ryegrass, can also absorb K twoto five times faster than the companion legume at theroot exchange sites. Therefore, when the two aregrown together, K fertilization is important to thesurvival of the legume. The legume needs to be ablefind abundant K in a small volume of soil composed ofits root-to-soil interface. Fertilizing with K also helpsthe legumes by promoting more root branching. Fertil-izing legumes with K then causes a compoundingeffect. Fertilizing with K on soils lacking sufficientavailable K will thus maintain the legume componentin legume-grass mixtures.

K applications should be done at least yearly. If yearlyrates call for 167 pounds per acre of actual K (200lb/acre K2O) or more, split the application to avoidluxury uptake of K during any one cutting. In areaswhere winter survival is critical to stand longevity,apply the last application of K fertilizer prior to lastregrowth. Split applications are especially importanton soils that have a low cation exchange capacity(< 7.0 milliequivalents per 100 grams of soil) to avoidleaching losses and nutrient imbalances on the ex-change sites.

Forage crops also remove large amounts of P. Theyremove about 15 pounds of P2O5 per acre for every tonof forage harvested. Forage production responds toannual maintenance applications of P better than toinfrequent heavy rate applications. This is primarilybecause much of the applied P is being renderedinsoluble (fixed or immobilized, see fig. 5–31) in mostsoils and thus unavailable for plant uptake. Even insoils with optimum levels of P, forage seedings oftenrespond to a banded starter fertilizer containing P bygrowing more vigorously and thicker.

Chapter 5



Both P and K availability are enhanced by liming acidsoils. P is most available when the soil pH rangesbetween 6.0 and 7.5. At either side of that pH range,much P can be precipitated out and rendered insolublefor plant uptake. With K, liming removes exchangeablealuminum (Al+3) from the soil cation exchange sitesallowing K to compete with Ca and Mg for those sites.Liming also increases the pH-dependent cation ex-change capacity (CEC) significantly. This creates moreCEC in the soil by creating more negatively chargedparticles in the soil. It is a continuous function increas-ing from a lowest value at a pH of 3 to a highest valueat a pH 9. The higher the CEC, the more K that can beheld in the soil as a plant available form.

Standard soil tests do not test for N in humid areas.Nitrogen fertilizer rates are given based on long-termfield trials of forage species at research farms scat-tered about those states in humid areas. The nutrientis too soluble and so subject to various transforma-tions in moist to wet soils that it is impossible tomeasure it accurately. The measured value also wouldnot have any meaning over the useful life of the soiltest. A nitrogen quick test produced for corn uses asoil sample taken when the corn is about 12 incheshigh. This snapshot in time can predict whether thecorn crop needs additional N fertilizer. This, too, isjust an approximation and correlates the concentra-tion of nitrate in the soil at that stage of corn develop-ment to the amount of fertilizer needed to produce thecorn yield desired. The reading itself, without thecorrelation data, is meaningless. It works best onground either receiving manure or that has residual Nfrom the previous year. It is not appropriate if highlyavailable N fertilizers have been spread or injected justbefore corn planting.

Naturalized and native haylands are primarily grassbased. Naturalized haylands, being primarily cool-season grasses in the North and subtropical or tropicalwarm-season grasses in the South, benefit by theaddition of N. Legumes are either absent or a minorcomponent (<10 percent by weight) in those grassstands (fig. 5–43). If manure is available, it can bespread at the rate to meet the N needs of the cropproduced. Manures and N fertilizers should be spreadbefore grass regrowth occurs at the beginning of theseason or after a cutting. The most efficient way ofapplying N is to split apply yearly requirements inhumid areas or on some irrigated pastures. These split

applications should equal the amount needed to pro-duce the forage growth expected for the cutting beingfertilized. If applied all at once, a high percentage canbe lost to leaching, runoff, denitrification, or volatiliza-tion before forage crop uptake. Grasses also take upexcessive amountsof N if excessive amounts arepresent in the soil. This can lead to nitrate poisoningunless ensiled and stored for 6 to 8 weeks beforefeeding.

Native haylands, being primarily temperate warm-season grasses and growing in more arid areas wherelittle N is leached or denitrified, may require little orno N. In humid climates N fertilizer can actually bedetrimental to temperate warm-season grass stands byfavoring cool-season grass invaders. Therefore, Nfertilization should be avoided unless applied in smallamounts late in spring at the outset of warm-seasongrass growth. In areas receiving 18 inches of rainfall,50 pounds of N per acre is sufficient. In areas receiving30 inches or more rainfall, 100 pounds of N per acreoptimizes yields of warm-season grasses. The goal isto avoid leaving any significant residual N in the soilfor cool-season grasses to exploit once cool weatherbegins again.

Naturalized or native haylands being mostly grassbased do not benefit much from pH adjustmentsunless the soil is extremely acid (<5.0) or extremelyalkaline (>8.7). So liming to reduce acidity or decreas-ing alkalinity through irrigation water management oracidification is rarely necessary for these haylands.Most grasses grow well within this range.

For forage crops grown in rotation with row crops,another method of fertilization may be the rotationmethod. This works particularly well when manuresare available for disposal. Most manures, when appliedat the N rate needed to produce the expected yield ofthe row crop, deliver higher rates of P and K to the soilthan that required annually by many row crops grownin association with forages. Yet, this is the most idealtime to spread manure for the following reasons:

• Row crops can use the N to greatest economicadvantage.

• Manure spreading can be done before row cropplanting and after harvest so that no crop dam-age can occur from smothering, salt burn, ortraffic injury.



Chapter 5

• Legume and legume-grass forage crops are notsubjected to unneeded N applications that canincrease planted or volunteer grass competitive-ness with the legume.

• Forage crops are also not fouled by manure thatcould lead to livestock health problems or atleast lower intake.

This method of fertilization leaves residual P and K inthe soil for the forage crops that follow in the rotation.The forage crops are then left in the rotation at leastlong enough to draw down the P and K to balance cropremoval with nutrient additions over the life of therotation. Some supplementary P and K may be added ifthe forage crop’s life in the rotation extends beyondthat needed to balance manure nutrient inputs withcrop removal.

This leads to one other method of fertilization, pre-scription application of nutrients. The prescriptionmethod accounts for the various possible sources ofnutrients on a fully integrated livestock farm or ranch.The sources include atmospheric deposition, feedpurchased, fertilizer, fixed nitrogen from previouscrops, manure, and soil.

Soil test results prescribe fertilizer amounts based onthe availability of soil nutrients. If soils test high,fertilizer amounts are reduced accordingly to the pointof recommending no more of a particular nutrient beadded. This portion of the prescription method is easyand accounted for in the soil test recommendations.The rest of the accounting procedure requires moretests and a mass nutrient balance worksheet.

Figure 5–43 Grass response to nitrogen fertilizer* (from Barnes, et al. 1995)

200 400 600 800 1,000 1,200 1,400 1,600 1,80000

10

20

30

40

50

60

Kg N per ha per year

Dry m

att

er y

ield

, m

t/h

a p

er y

ear

Tall fescue, WIOrchardgrass, IN

Tall fescue, TX

Coastal bermudagrass, TX

Napiergrass, Puerto RIco

* Note tropical and subtropical warm-season grasses have greater response to very high rates of N than that of the cool-seasongrasses. Also note longer growing season increased tall fescue yield and response to N.

Chapter 5



In areas where atmospheric deposition of N is signifi-cant, an annual deposition rate is included in thecalculations. In some cases it is ignored because ofoffsetting N losses, such as denitrification, that areknown to occur, but do so at unpredictable rates.

Manure, where applied, should be tested for nutrientvalue. Book values reported in the literature are aver-ages and may have nothing in common with the ma-nure being spread. This manure test picks up thenutrients being brought onto the farm through feedsupplements. The manure analysis reflects what thelivestock are eating. This is often why the onfarmmanure analysis differs so widely from literaturevalues. Another reason for the possible disparity is theway manure is stored and handled on the farm versushow it was stored as cited in the literature. Losses of Nand K can be substantial if the liquid fraction of thewastes escapes collection. Ammonia N can also vola-tilize away during collection, storage, and application.The rate of application of manure should be calibratedso that there is a known rate of application associatedwith manure usage. If manures are applied, they areadded to the supply ledger.

If legumes are in the crop rotation, the next crop orthe legume’s companion crop in the rotation willbenefit from the nitrogen released from the decayinglegume residue, roots, and aerial parts. Their contribu-tion to the N supply can be estimated by using tablessimilar to table 5–5 developed for your area. Care mustbe taken not to over estimate their contribution. If thelegume stand is thin or has become very grassy, littlecarryover of N to the next crop occurs. Once thenutrients are accounted for from these sources, theyare subtracted from the amount of commercial fertiliz-ers recommended in the soil test recommendations.Landowners or managers that have the ability to usemanures and legumes in their cropping systems cansave on fertilizer expenses. They also must realize thatpurchased feed serves a dual purpose: It feeds live-stock and ultimately the crops on the farm.

From a water quality standpoint in many watershedsaround the Country, N and P loadings on farms needto be closely tied to crop utilization and export of cropand livestock products. These two nutrients are caus-ing downstream pollution and eutrophication in re-ceiving water where uncontrolled high inputs of thesenutrients occur in some watersheds. Where foragecrop and pasture lands impact these watersheds,

dairies, being intense livestock enterprises, tend to bemajor nonpoint sources of N and P. In particular theytend to be phosphorus accumulators because theimportation of feed supplements and purchased fertil-izer outweigh the export of P in milk and meat.

P can leach as readily as N on some sandy soils havinglittle ability to fix or immobilize P as water insolublecompounds. Therefore, P can reach receiving water byshallow groundwater interflow as well as by surfacerunoff. Nitrogen can also move via these two pathways.

Dairy cattle are fed high protein diets to produce milk.If not supplemented with the right proportion ofrumen degradable protein to rumen undegradableprotein, much of the rumen degraded protein leavesthe animal as urea in the urine rather than as proteinin the milk. This elevates the nitrogen excreted eitherin the pasture or on the confined area. Depending onthe management of the confined area, nitrogen mayleave it as surface runoff or be disposed of later asmanure on forage crop land. There, it may be subjectto further loss by leaching or runoff. Therefore, nutri-ent management planning is as critical to grass basedfarming as is the forage-livestock balance sheet toachieve total whole farm planning.

Potassium is also becoming an important factor innutrient management. As mentioned under nutrientmanagement on pasture, high levels of K in foragescan affect animal health adversely. Dry dairy cows 2 to3 weeks from freshening need grass forages with thelowest K concentrations available to avoid milk feverand other symptoms caused by a cation-anion imbal-ance in their diet. However, heavy fertilization or highfeeding rates of off-farm produced feedstuffs causesoil K levels to become high or excessive on fieldsreceiving most of the animal waste. Luxury uptake ofK by grasses builds K concentrations in the grasseswell in excess of 3 percent of dry weight (fig. 5–44).Late dry period cows should be fed a total ration withnot more than 0.8 percent K in it. If the grass has morethan 2 percent K in it, the ration becomes difficult tobalance. It must involve other feedstuffs containingmuch less K to dilute the concentration.

Legume forage crops are sensitive to low soil levels ofsulfur (S) and boron (B). When growing legumes,alone or with grass, on hayland or on cropland inrotation with other crops, specify that these twonutrients be evaluated when sending in soil samples.



Chapter 5

On strongly acid soils, molybdenum (Mo) may alsolimit legume growth. It is directly responsible for Nfixation by Rhizobia and for N assimilation and pro-tein formation in the plants. These nutrients can beadded to a blended fertilizer and spread with otherrequired nutrients. Standard soil tests do not test forthese nutrients.

Soil tests for forage crop production should be takenat least once every 4 years or per crop rotation cycle.Soil sampling in late summer or fall gets reliable Kresults. Soil tests should be taken at least a year beforeseeding back to a perennial forage crop. This is par-ticularly important where stand longevity is critical tomaintaining the correct rotation length and avoidingfrequent renovation events on permanent hayland.This allows the producer to correct soil pH and micro-nutrient deficiencies or build soil levels of P and Kbefore planting the perennial forage crop. The chancesof establishing a thick stand and ensuring its long-termsurvival are greatly enhanced by having adequate soilfertility before establishment. Soil tests, to have anyvalidity, must be taken in areas of the field that havethe same soil type, topo-graphy, and cropping history.Several soil plugs or slices should be taken randomlywithin the area of like conditions. These are thenmixed and a composite sample taken from that. Eachsample must be clearly identified as to soil type, fieldnumber, and location in the field.

With precision farming, soil samples can also becollected in a grid pattern that is mapped using globalpositioning system (GPS) technology. This establishesa geo-referenced pattern of soil fertility over the field.Fertilizer trucks equipped with geo-referencing de-vices can spread fertilizer at variable rates across thefield based on the soil fertility map superimposed overthe field map. This avoids placing too much or toolittle fertilizer in areas of differing soil fertility acrossthe field.

Soil samples also must be sent to a soil test laboratorythat uses the proper extraction methods for the soilsampled and has knowledge of the soil’s response tofertilizer. In some states this is easily done by sendingsamples to the land grant university facility. However,some land grant universities no longer have such afacility for public use. In those states private laborato-ries are certified by the land grant university. Much ofthe controversy over the validity of soil testing wasbecause of the mistaken belief that soil testing proce-dures are the same nationwide. They are not andshould not be. Soil chemistry varies too widely overthe Nation to have one perfect extraction procedure.Soils also vary in their response to fertilizer. Laborato-ries without access to field trial data for the soil typelisted on the soil test form cannot give accurate fertil-izer recommendations. The recommendations theygive will be high to avoid under estimating amountrequired and incurring blame for a poor crop response.

Plant tissue samples can also be taken to indicate thecurrent status of nutrient sufficiency in the foragecrop. The results are compared to reference nutrientconcentrations of a "normal" forage at a specified yieldlevel. Tissue testing can reveal any nutrient imbal-ances, but the soil test accompanying it helps deter-mine the cause of the imbalance. Tissue testing aloneonly tells you whether or not you have a problem. Itcannot tell you why it is occurring.

Figure 5–44 Influence of potassium available in the soil topotassium content in grasses (adapted fromBrady 1974 and Bosworth 1995)

Potassium required foroptimum growth

Luxurypotassium

KContentof grass

% D

1.5-2.0

LowLow

High

HighPotassium available in soil

Potassium contentof grasses

Chapter 5



(c) Accelerating practice—Hayplanting

This practice is used to renovate permanent haylandor reintroduce hay-crop forages on a field where acrop rotation is used. It does not include row cropplantings that might be harvested as a forage crop,such as corn silage. The full title of the practice stan-dard in the FOTG is Pasture and Hay Planting. As withpasture plantings, hay plantings are done for severalreasons:

• To reintroduce legumes back into permanenthayfields that have gotten increasingly grassy.This improves forage quality and often increasesforage yields by increasing plant density andfixing atmospheric N.

• To introduce newly improved cultivars of grassesor legumes not before used by the producer.These varieties have improved disease and/orinsect resistance and greater productivity.

• To introduce wholly different forage species thatare better adapted to the site's climate, soils, andharvest regime.

• To introduce forage crops into a crop rotationthat will balance crop removal of nutrients tothose applied as manures over the life of the croprotation.

• To introduce hay-crop legumes into a crop rota-tion to provide organic N to the next crops in therotation. For instance, depending on the rate ofdecomposition, alfalfa may provide residual Nfor up to 3 years of crop production.

• The same planting techniques can be used toplant cover crops in orchards and vineyards oron cropland. On cropland, the cover crops retainsoil nutrients in the root zone, provide groundcover and organic residue, and may fix additionalN for the production crop's benefit. They may betilled into the soil or burned down with herbi-cides before the next production crop's plantingor left as a living cover crop.

• To improve soil quality by increasing soil organicmatter (primarily through root mass accumula-tions) and soil particle aggregation. Root exu-dates and expansion cause soil particles to bindtogether by supplying a gluing agent and applyingpressure.

• To provide excellent ground cover and rootbinding to protect the soil from erosion whilethey are in the crop rotation, thereby reducingoverall soil erosion rates where applied.

• Where the plantings are properly sited, theyprovide crops that can trap wind blown soil,filter sediment and nutrients from runoff water,and intercept nutrient laden shallow interflowwater with their roots. These areas may be trapstrips or vegetative barriers in wind erosionprone fields. They may serve as vegetative filtersalong watercourses or waterbodies and at loweredges of sloping row crop fields. They may behay-crop strips alternated with tilled stripsacross the hillslope or the prevailing wind direc-tion in stripcropping layouts. On vegetative filtersites, to be truly effective in removing nutrients,the forage should be harvested as a hay-cropanyway to remove the nutrients stored in theplant tissue. Otherwise, the nutrients will eventu-ally make their way to the watercourses targetedfor protection.

(1) Hay-crop plantings

Hay-crop forage plantings generally contain only oneor two species for ease of management. As the standsmature, other species of plants, desirable or undesir-able, invade as openings in the canopy permit. Either apure grass or legume stand is the easiest to manage.Weed control is easier because most herbicides pres-ently on the market cannot kill the weeds withouteither killing the grass or the legume at the same timedepending on their chemistry. Grasses tend to be quitecompetitive towards legumes having stronger rootsystems, a taller canopy, and faster leaf growth. There-fore, without fertility and harvest measures to favorthe legumes, grass-legume mixtures eventually be-come grass only stands. However, most binary seedingmixtures for hay-crop seedings contain a legume and agrass. The advantages to doing that even thoughmaintaining two different plants is difficult are:

• Legumes reduce the need for N fertilizers be-cause they fix N.

• Legumes improve forage quality because they aremore digestible and have higher protein concen-trations.

• Most legumes can produce good hay cuttingsduring the summer when cool-season grasscomponents produce little or nothing.

• Grass-legume mixtures tend to provide a densercanopy suppressing weeds from invading in thefirst place.



Chapter 5

• Theoretically, grasses can protect legumes fromfrost heave damage on soils where this com-monly occurs. There may be some value, but it isinconsistent and very much subject to the sever-ity of the winter conditions that cause frostheave.

• Grass-legume mixtures tend to dry down fasteras hay and ensile better than pure legume mix-tures.

• Grasses alone generally have to be ensiled wetterto achieve required packing to exclude oxygen.

• A grass-legume mixture provides insurance fromcrop failure because if the legume dies out unex-pectedly, the grass remains to provide some yielduntil the field can be scheduled for renovationagain.

• Grasses tend to prevent legumes from lodging(laying over with no recovery after a hard rain orwind storm).

• Legumes grown with grasses reduce nitratepoisoning and grass tetany cases in livestock ifthe stand is 40 percent or more legume.

(2) Grass-legume mixtures

Hay-crop grass-legume mixtures should contain alegume and a grass that have similar maturity dates,are compatible in height, and adapted to the haycutting regime of the operator. This generally goesbeyond just getting compatible species together. Italso requires getting varieties together that are mostcompatible in maturity timing and cutting intervaltolerance. As mentioned before under pastureplantings, common varieties of many grasses havediffering maturity dates to the legume standard, al-falfa. Some mature before the alfalfa is ready andothers mature much too late for quality alfalfa hay orensilage. Grass varieties must be selected that matureat the same time the alfalfa is entering the harveststage of maturity that the producer likes.

The decision to renovate pure legume stands or grass-legume stands hinges on the number of legume plantsleft per square foot. Most legumes need only 6 to 8plants per square foot in established stands to producemaximum yields. Alfalfa stands with less than 3 plantsor 25 stems per square foot, whether or notgrass ispresent, are in need of renovation. Alfalfa forage yieldat this point is unacceptable if it is really beingcounted on for its quality and production. Othercrowned legumes at 4 plants per square foot producesonly about 50 to 60 percent of their potential yield.

(3) Herbicide use

Hay-crop forages should not be planted immediatelyafter other crops treated with herbicides that havecarryover residual effectiveness from one crop to thenext. The triazine herbicides called atrazine,metribuzin, and simazine, chloroacetamides calledacetochlor and dimethenamide, imidazonlinonesnamed imazethapyr and imazaquin, clomazone, andtank mixes or premixes containing these herbicidesshould not be used the year before a hay-crop plant-ing. Reduced rates of any single chemical the yearbefore seeding may lessen injury, but crop damagemay still occur depending on soil type and rainfallamounts received between last herbicide applicationand hay-crop planting. A reduced rate may avoid astand failure, but stand vigor may be unacceptablylow.

If an application of lime is needed to reduce soil acid-ity before seeding a hay-crop, an application at least ayear in advance releases any applied triazines boundto soil particles. If done just before cool-season hay-crop seedings, the triazines released may be enough tocause an establishment failure. If the soil was thatacid, the liming would have actually made the triazineweed control more effective for the row crop treated.Sulfonylurea herbicides have a shorter carryovereffect, but can go into the next crop year. The timeinterval between last application of them and hay-cropseeding must be separated sufficiently. Crop restric-tion periods range from 9 to 16 months for alfalfa andclovers. A summer hay-crop planting of alfalfa orclover is safer than a spring planting if sulfonylureaherbicides were used the year before. Flumetsulamhas a long cropping restriction on it for clovers, 26months and still needs to be bioassayed to see ifactivity is still there. It has only a 4-month restrictionon it for alfalfa.

The management message is to be extremely careful incrop rotations not to apply herbicides to a previouscrop that may do crop damage to the next one in therotation. New herbicides are registered each year andothers are taken off the market. Labels are subject tochange and may become more restrictive. Some herbi-cides are registered for use in some states and notothers. All herbicide users should carefully read herbi-cide labels and proceed with treatment only after theyare sure they understand the environmental conse-quences of their actions. The information in thepreceeding two paragraphs should not be considered a

Chapter 5



definitive source at the state level. These paragraphswere done in some detail to point out the complexityof the management issue involved.

(4) Seeding failures

Seeding failures can also occur from natural chemicalscalled allelopathic compounds. Sometimes considereda defense mechanism to protect the plants alreadygrowing on the site, allelopathic compounds arechemical substances that inhibit the growth of seed-lings of the same species or competing species. Thesechemical substances are either secreted or leachedfrom plants or are toxic degradation products from oldcrop residue. If the allelopathic compound interfereswith the germination and development of seedlings ofthe same species, the effect is called autotoxicity. Thislatter effect has been attributed to alfalfa and cloverseeding failures when new seedings are planted imme-diately after a preceding crop or into a thin stand ofthe same genera.

Autotoxicity has a name in the case of clover. It iscalled either clover-sick soil or clover sickness. In thiscase some researchers isolated some phenolic com-pounds that were degradation products ofisoflavonoids contained in the clover herbage thatinhibited germination of red, white, and alsike cloverseeds. They also inhibited red clover seedling growth.Presently, it is not recommended to reseed by com-plete renovation or overseed alfalfa into old, thinstands of itself because of the strong evidence that it isautotoxic. If the thin stand is less than 1 year old, a no-till alfalfa seeding into the existing stand is unaffectedby autotoxicity. To avoid autotoxicity problems onolder stands, kill all old plants at least 6 months beforethe next seeding. Generally, this allows for enoughdecomposition and leaching of toxic compounds todilute their effect on the new seedlings. A surerautotoxicity avoidance measure is to totally eradicatethe old alfalfa and rotate to another crop for at leastone year before reseeding back to alfalfa.

Tall fescue, orchardgrass, redtop, quackgrass,ryegrass, timothy, Johnsongrass, bermudagrass,bahiagrass, pangolagrass, rhodesgrass, and Dallisgrasshave all been implicated in being allelopathic to vari-ous legumes and grasses seeded into them. Ball cloverwas most affected by the warm-season grasses fol-lowed by arrowleaf and white clovers. Crimson cloverwas unaffected. Tall fescue is variable in its allelo-pathic effect on legumes. It appears that specific

genotypes are allelopathic while others are not.Birdsfoot trefoil, rape, and medium red clover germi-nation and growth have been retarded by some tallfescue genotypes. Even large crabgrass growth wasexcluded in some tall fescue stands. Quackgrasstoxicity has been studied extensively, but evidence isinconclusive on its being allelopathic. It may be morerelated to its aggressive rooting and dense canopynature. For legume hay-crop plantings, grass eradica-tion before seeding is best. A crop rotation than in-cludes a year or more of crop production that usesclean tillage, herbicide treatments, or both, to kill oldsods of these grasses is desirable.

Seed quality is important whether it be a pasture orhay-crop planting. Certified seed should be usedwhenever possible to guarantee the variety of choice isactually what is in the bag and the quality of the seedscontained in the bag. Seed tags should show speciesname, varietal name and/or number, lot number, thegermination percentage of the forage species stated onthe tag, germination date, the percentage of pure seed,the percentage of other crop seed, the percentage ofweed seed, the percentage of inert material (chaff,seed coatings, soil), the percentage of noxious weedseeds, the percentage of hard seed (species depen-dent), total germination and hard seed, origin of theseed, and weight of the bag.

Seeding methods, depths, and rates; seed treatments;and pest management covered under the pasturemanagement section equally apply here. Please referto pasture planting for those management items. Onenotable exception is a pest management concern onalfalfa planted into sods or heavy residue. Most alfalfaseedings are done on hay-crop land, so it is coveredhere. Slugs can be a serious problem on spring orsummer no-till alfalfa seedings in sods, heavy cropresidue, or heavily manured fields. Some tillage toreduce the ground cover may be necessary to destroythe slug’s habitat. Presently, there are no molluscideslabeled for use on forage crops used for forage, onlytheir seed crops. Slug damage can occur on severalother forage species where cool, moist, trashy soilconditions prevail.

(5) Evaluation of forage seeding

Evaluation of the successfulness of a forage seedingestablishment should occur about 5 months after theseeding or at first harvest, whichever comes first.Sometimes this can be just a visual scan across the



Chapter 5

Table 5–7 Minimum number of plants per square foot toachieve a full stand 1/ 2/

Species Minimumnumber/ft2

Alfalfa 20 3/

Alsike clover 15

Birdsfoot trefoil 15

Cicer milkvetch 7

Crimson clover 20

Crownvetch 7

Kura clover 15

Red clover 15

Sainfoin 7

Sweet clover 7

White (Ladino) clover 10

Orchardgrass 50

Reed canarygrass 50

Ryegrass 60

Smooth bromegrass 15

Tall fescue 50

Timothy 30

1/ Sources: Cornell Field Crops and Soils Handbook, 1987; Hanson,A.A., et al. Alfalfa and Alfalfa Improvement, 1988; Knight, W.E.,The Effect of Thickness of Stand on Distribution of Yield andSeed Production of Crimson Clover, 1959; Piper, C.V., ForagePlants and Their Culture, 1941; Sheaffer, C.C., Forage Legumes,1993; Sprague, M.A., Seedling Management of Grass-LegumeAssociations in the Northeast, 1963.

2/ For pure hay-crop stands of the species named at 5 months fromplanting date or first harvest, whichever comes first. Rainfedareas receiving at least 16 inches of rainfall during the growingseason or irrigated lands.

3/ Alfalfa is an average value going from an arid (14 plants) tohumid (26 plants) climate.

field and deciding the stand is uniform, thick, and lush.In situations where weather conditions or other stressfactors have created a questionable stand in terms ofnumbers and vigor, an assessment of whether toreseed or overseed or plant to another crop is needed.Stand counts based on the number of plants persquare foot are taken randomly across the field. Guide-lines for some common forage legumes and grassesare given in the table 5–7. These values should beviewed as guidelines only for pure stands during theestablishment period.

The ultimate decision to destroy the stand and replaceit with a new seeding or another crop ultimately restswith the producer. The numbers are high to suppressweed growth and optimize first year forage yield.Since perennial plants do little tillering the first year,they must be thick in numbers to form a closedcanopy. The numbers can be considerably lower forperennials (6 to 8 plants) in later years and still pro-duce maximum yields. Over time they will thin out asweaker individuals are crowded out by the morevigorous ones. Perennial plant numbers are virtuallymeaningless after the establishment year. Stem countsare more valid in rating stand density. Sod formers andstoloniferous plants lose their identity as individualplants. Crowned plants, if healthy, produce morestems as plant numbers decline.

If the numbers observed in the field during the estab-lishment period are somewhat lower than those givenin table 5–7, remedial measures can be taken to makethe best of the situation. Weeds should be suppressedwith herbicides if they threaten to overtop the foragecrop. A more lenient forage harvest management canput less strain on surviving forage plants. This mightinclude higher stubble heights, less frequent cuttings,and more advanced maturity stages for the legumes.This will build food reserves and keep canopy closedfor longer periods to suppress weed competition.Some additional fertility may also be in order if leafcolor and tissue analysis indicate less than optimumnutrient levels. On irrigated land, close monitoring ofsoil moisture can help to avoid any water stress thatwould harm development.

Hay-crop plantings may be clear seeded or plantedwith a companion crop, such as spring oats or barley.If a companion crop is seeded with the hay-crop, itmust be sown at no more than 75 percent of its normalseeded alone rate. This reduces competition for water,

allows for more light penetration to the lower canopyof forage seedlings, and decreases to some extent itslikelihood of lodging under wet conditions. Ideally, thecompanion crop should be removed early as an ensi-lage crop. If it is allowed to mature for grain, the strawwindrows left by the combine should be baled as soonas possible. Windrows left in place for prolongedperiods smother the hay-crop seedlings lying beneaththem.

Chapter 5



(d) Accelerating practice—Irriga-tion water management

This practice is used primarily in rainfall limited areasto produce high quality hay-crop forages for livestock.Eighty-one percent of all irrigated acreage occurs inthe 17 contiguous Western States. Much of the acreagedevoted to hay-crops is sown to alfalfa. General guide-lines are given here only because of the regionaldifferences in evapotranspiration, soils, effectiverooting depth, species and cultivars used, and irriga-tion methods used that affect water usage. Other fieldspecific environmental factors that influence waterusage are age and vigor of the forage being irrigatedand soil nutrient status.

The primary methods of irrigation are gravity andsprinkler. Under these two general methods are spe-cific types of irrigation used for pasture or hay-cropland. Gravity irrigation types used for pasture or hay-crop land are border-strip, corrugation, flood, andwild-flooding. They benefit from land that has beenleveled first. With wild-flooding, however, this is lesslikely because the terrain is generally too uneven to beleveled.

Sprinkler irrigation types used for pasture or hay-cropland are center pivot, portable, solid set, and travelinggun. A less common method of irrigation is calledsubirrigation. It requires nearly level land and a shal-low water table that can be elevated and lowered witha water control structure at the ditch or tile mainoutlet that drains the field being subirrigated.

(1) Soil water criteria

Soil water criteria are used to determine irrigationscheduling where applicable rather than plant basedcriteria. By the time visual symptoms appear, yieldreductions will frequently occur. Two soil water crite-ria are used. One is based on available water, and theother on extractable water.

(i) Available water criteria—Available water inthe effective root zone is the amount of water releasedby the soil when the equilibrium soil water matrixpotential is decreased from field capacity (0 bar) topermanent wilting (-15 bar). This is the portion ofwater in a soil that can be absorbed by plant roots.Using this criterion, available water is allowed to bedrawn down by the crop, typically 40 to 65 percent,before irrigation commences.

(ii) Extractable water criteria—Extractablewater is a lesser quantity of water than availablewater. It is the difference between the amount ofwater held by the soil at field capacity and the waterremaining in the effective root zone when severewilting of the crop occurs. In this case, however, agreater depletion percentage is allowed before irriga-tion commences, typically 65 to 75 percent.

The goal of either method is to prevent a decrease inplant transpiration. With a decrease in transpirationrate, there is a corresponding decrease in yield. Adecrease in transpiration means the plant is undergo-ing water stress. Water stress decreases stem numbersand diameter, internode number and length, and leafsize. Moderate water stress lowers alfalfa yields, butproduces a leafier product. Under severe water stress,however, lower leaves drop off, resulting in a stemmy,low yield cutting of alfalfa.

When soil water depletion is used as an irrigationcriterion, water depletion is monitored most often inthe upper 3 feet of soil rather than from the full effec-tive root zone. However, there are instances whenmonitoring the lower part of root zone is of value. Itprovides information on potential storage of excessiverainfall that might occur after an irrigation event. Thiscan often happen in humid and subhumid areas. Thisallows the storage of rain that might otherwise be lostto deep percolation if the entire root zone was at fieldcapacity. It is also important for the control of solublesalt leaching in saline or sodic soils.

Soil water depletion can be monitored directly, indi-rectly, or based on evaporation pan or climatonomicmodels that estimate maximum daily water use orevapotranspiration (ET). Direct measurements are notused by producers because of their expense andoperating difficulties. Indirect measuring devices arecalibrated soil tensiometers, neutron meters, or timedomain reflectometry. The procedure involving ETestimates either from pans or the Penman, Priestley-Taylor, Jensen-Haise, and Makkink formulas cali-brated for the particular crop and climate situation ismost often used. Crop coefficients are developedduring various crop growth stages throughout theyear.

Once ET estimates have been developed, irrigation canbe scheduled using a water budget. This budget sums



Chapter 5

soil water depletion using one of the climatonomicestimators and deducts water inputs from precipita-tion or irrigation. This provides a net soil water status.This simplistic procedure can have cumulative errorsintroduced from erroneous ET estimates or waterinput assumptions. It should be verified with tensiom-eters or other soil water measuring devices to avoidover or under applying irrigation water.

Excessive moisture supplied by irrigation or rainfall isdetrimental to alfalfa root and shoot growth and tostand persistence. In the desert irrigated regions,alfalfa can be scalded by nearly saturated, high tem-perature soils. These plants most often die within 3 to4 days. Over-irrigating alfalfa immediately after cuttingwhen little regrowth has occurred leads to severeplant stress and stand thinning. The roots are deprivedof oxygen, and toxic concentrations of ethanol andother substances build up in them. Leaf loss starting atthe base of the plant and death of xylem tissue results.Since growth of phytophthora root rot fungi is favoredby wet soils, this infection can be a secondary cause ofstand loss. In more northern or higher elevation irri-gated areas, excess soil moisture during the latter partof the growing season can decrease freezing toleranceof alfalfa plants and lower winter survival.

It takes from 1 to 1.5 acre-inches of water to produce aton of alfalfa hay per acre. Maximum daily water useor ET of alfalfa is typically 0.2 to 0.5 inch. Daily ETrates vary based on global radiation, plant growthstage, air temperature, and day length. The highest ETrates occur during full plant canopy on hot, long,windy days with low humidity. Seasonal alfalfa ETrates range from 14 inches in the Northeast or PacificNorthwest to 74 inches in the arid Southwest. Table5–8 gives the typical seasonal ET values for alfalfa byregions in the Western United States. For a compari-son with other forage crops, see table 5–9, Seasonalconsumptive-use requirements of some forage crops.

Irrigating a field's soil-to-field capacity before seedbedpreparation enhances germination and emergence.This avoids applying water to planted seedbeds onsoils prone to washing and crusting. Irrigation shouldcommence after emergence to increase root penetra-tion and growth. Seedling roots are suppressed morethan shoot growth by moisture stress.

Table 5–8 Total seasonal consumptive use of water byalfalfa in Western United States (fromHughes, H.A., Conservation Farming, 1980)

Location Growing season Seasonalconsumptive

use(days) (inches)

Southern coastal 300+ 36250 – 300 30

South Pacific, 250 – 300 37coastal interior, 210 – 250 32and northern coastal 180 – 210 26

150 – 180 22

Central valley, California, 250 – 300 40and valleys east side 210 – 250 34of Cascade Mountains 180 – 210 30

150 – 180 26120 – 150 20 90 – 120 14

Intermountain, desert, 250 – 300 52and western 210 – 250 44high plains 180 – 210 36

150 – 180 30120 – 150 24 90 – 120 19

Table 5–9 Seasonal consumptive-use requirements ofsome forage crops (from Hanson, A.A.,Practical Handbook of Agricultural Science,1990; Hughes, H.A., Conservation Farming,1980)

Crop Fraction of alfalfawater requirement

Alfalfa 1.0

Bromegrass 1.16

Corn 0.65

Pasture 0.90 (variable)

Red clover 0.90

Chapter 5



(2) Water quality requirements

Water quality requirements for irrigation water areimportant. Concentrations of boron, chloride, sodium,and salt must be monitored to prevent crop damage.Water is classed based on its content of boron, chlo-ride, sodium, sulfate, and electrical conductivity. Theclasses for boron and chloride are rated starting withthe purest water named excellent and followed withdecreasing quality by good, permissible, doubtful, andunsuitable. Sensitivity to these contaminants varieswith forage species. They are ranked as sensitive,semi-tolerant (medium tolerant), and tolerant. Table5–10 gives classification of irrigation water based onboron and chloride content. Refer to table 3–6 inchapter 3 for salinity tolerance ratings of variousforage crops.

Forage crops are rather tolerant of high boron concen-trations in the soil. Some forages and their tolerancelimits to boron are shown in table 5–11. Figure 5–45graphically shows the USDA irrigation water classifi-cation based on water sodicity and conductivity. Insodic, nonsaline soils, Ca and Mg are often deficientfor good plant growth. Sodic irrigation water mayinduce Ca and various micronutrient deficiencies inthese soils. In sodic-saline soils, the salinity of thewater becomes more important because of its osmoticeffect on plant roots (burning). Sodic irrigation watercan also reduce soil permeability and tilth because thesodium ion acts as a soil dispersant. It also causes thesoil to crust badly as well, which impedes seedlingemergence. A computerized and noncomputerizedversion of WATSUIT can be used to determine thesuitability of irrigation water for a specific site andcrop.

Table 5–10 Classification of irrigation water based on boron and chloride content (from Hanson, A.A., Practical Handbookof Agricultural Science, 1990)

- - - Class of water - - - - - Concentration (meq/L) - - Hazard characterizationindex grade boron chloride

1 Excellent <0.5 <2.0 Generally safe for sensitive crops.

2 Good 0.5 – 1.0 2.0 – 4.0 Sensitive crops generally show slight to moderate injury.

3 Permissible 1.0 – 2.0 4.0 – 8.0 Semi-tolerant crops generally show slight to moderate injury.

4 Doubtful 2.0 – 4.0 >8.0 Slight to moderate injury for some tolerant crops.

5 Unsuitable >4.0 Hazardous for nearly all crops.

Figure 5–45 USDA classification of irrigation water*(from Wild 1988)

30

28

26

24

22

20

18

16

14

12

10

8

6

4

20

Low

S1M

ediu

mS

od

icit

y h

azard

Salinity hazard

S2H

igh

S3S4

Very

hig

h

C1-S1

C1Conductivity dS m-1 at 25°C

Low

ClassC2

MediumC3

HighC4

Very high

C1-S2

C1-S3

C1-S4

C2-S1

C2-S2

C2-S3

C2-S4

C3-S1

C3-S2

C3-S3

C3-S4

C4-S1

C4-S2

C4-S3

C4-S4

0.1 0.25 0.75 2.25 5.0

* The higher the total salt content of the irrigation water (asmeasured by its conductivity), the lower must be its sodiumabsorption ratio if the exchangeable sodium percentage of thesoil is to remain below the level needed to produce adequateyields of the crop being raised.



Chapter 5

Table 5–11 Boron tolerance limits for some forage crops(from Stewart, B.A., and Nielsen, D.R.,Irrigation of Agricultural Crops, 1990)

Forage crop Threshold(ppm)

Sensitive

Perennial peanut 0.75 – 1.0Wheat 0.75 – 1.0

Moderately tolerant

Barley 2.0 – 4.0Bluegrass, Kentucky 1/ 2.0 – 4.0Corn 2.0 – 4.0Oat 2.0 – 4.0Clover, sweet 1/ 2.0 – 4.0Turnip 2.0 – 4.0

Tolerant

Alfalfa 1/ 4.0 – 6.0Vetch, purple 1/ 4.0 – 6.0

Very tolerant

Sorghum 6.0 – 10.0

1/ Tolerance based on reductions in vegetative growth.

Irrigated saline soils need to be leached on a timelybasis to remain productive. Salts tend to build up insaline soils as plants extract water from the root zoneand water is lost at the ground surface by evaporationbetween irrigation events. Evaporation and the quickdrying of plant roots in the upper part of the soilenhance the potential for upward water movement.This upward water movement carries salts fromdeeper in the soil profile towards the surface, espe-cially where a shallow saline water table exists. Saltsmust be removed by leaching to maintain the saltbalance of the soil at an average salinity level compat-ible with the crop being raised. The fraction of totalirrigation water needed to leach these salts throughthe root zone is called the leaching requirement (Lr).The fraction of total irrigation water that often perco-lates through the root zone as a result of irrigationinefficiencies is called the leaching fraction (L). Im-proved irrigation water management can reduce L tocoincide with Lr. This can reduce downstream salin-

ization because in concert with irrigation, drainage(open ditch or subsurface) must be provided to carrythe leached salts away from the root zone. Drainage isalso necessary in areas where the water table needs tobe lowered to the proper depth to enable leaching andprevent upward flow of soil water into the root zone.Not only is less salt leached from the field, but less saltis applied when saline irrigation water is used becauseof the lower application rate. The required leachingcan be achieved two ways. One way is to apply enoughwater at each irrigation to meet the Lr. The other is toschedule leaching irrigation that removes the saltsaccumulated by previous irrigations.

The salt balance or time-averaged root zone salinity isgreater in soils that are irrigated less frequently than insoils that are irrigated more frequently, all other fac-tors being the same. Saline soils benefit from morefrequent irrigation to maintain them at a wetter condi-tion than nonsaline soils. This keeps the soil salinitylevel lower. Figure 5–46 shows how the targetedaverage root zone salinity, based on the crop grown, isaffected by the electrical conductivity of the irrigationwater and the leaching fraction chosen. When theirrigation water salinity is higher than that required toachieve a no yield-loss threshold value for the pre-ferred crop, some crop yield reduction occurs unless amore tolerant crop or a higher Lr is selected.

Sometimes excessive levels of salts in soils cannot bereduced through normal irrigation applications andcrop management. Cropping is discontinued for awhile and a deliberate effort to leach the salts and/orsodium is begun. In the case of sodic soils, soil amend-ments and leaching may both be required to reduceexchangeable sodium. When reclaiming saline soils,leaching requirements can be determined by measur-ing bulk soil electrical conductivity. This can be mea-sured by soil electrode probes or electromagneticinduction instruments held by hand aboveground. Theprogress of salt removal is immediately measured bysuch devices. Boron is more difficult to leach. It takesabout the twice the irrigation water to remove a givenfraction of it as to remove soluble salts by continuousponding. The act of irrigation itself tends to releasemore boron by hastening mineral weathering of thesoil.

Irrigation water management that reduces salt uptakeby forage crops prevents them from becoming toosalty for animal consumption. Livestock fed high salt

Chapter 5



forage often get severe diarrhea and are dehydrated asa result. Often during reclamation forage crops areused to dry the soils some to improve salt removalefficiency. This prevents large pore bypass of waterleachate that often occurs during saturated flow.These crops are best plowed under as a green manurecrop. If harvested, they remove less than 5 percent ofthe soluble salts in the root zone. This is less than theamount normally applied back with the irrigationwater. It also avoids livestock health problems whileimproving soil tilth. Organic matter returned to sodicsoils improves soil aggregation a great deal.

Figure 5–46 is an example nomograph used to selectthe proper leaching fraction based on the average rootzone salinity target required to grow the selected crop

without yield loss and the electrical conductivity of theirrigation water available for use. Conventional irriga-tion commonly used for forage production allows thesoil to dry between irrigations. Using the same leach-ing requirement fraction of 0.5, irrigation water mustbe much less saline (2.9 dS/m) to keep the averageroot zone salinity level in the soil at the proper level togrow alfalfa than it would (5.4 dS/m) to grow milo(grain sorghum). Both crops could receive irrigationwater classified as C4, very high salinity hazard (fromfig. 5–45) at this leaching requirement fraction. At aleaching requirement fraction of 0.3, alfalfa mustreceive irrigation water classified as C3 (0.75 to 2.25dS/m) to keep the average root zone salinity at a levelthat would not lower alfalfa yields.

Figure 5–46 Assessing salinity hazards using conventional irriation (adapted from Stewart 1990)

(Sunflower)

(Wheat)

(Sugar beet)

(Cotton)(Barley)

(Milo)

(Sudan)

(Alfalfa)

(Corn)

(Citrus)(Beans)

Average r

oo

tzo

ne s

ali

nit

y, σ

e, d

S/m

00

1

2

3

4

5

6

7

8

9

10.05 .1 .2 .3

.4

.5

2 4 6 8 10 12

Tolerant crops

Thresholdtoleranceof crops

Sensitive crops

Moderately sensitive

Moderately tolerant

Electrical conductivity of irrigation water, dS/m

Leaching requirement



Chapter 5

(e) Accelerating practice—Soilamendment application

Soil amendments are organic and inorganic soil condi-tioners used to improve the chemical, physical, orboth, condition of the soil. Although they may addsome nutrients, their primary function is to improvesoil tilth or decrease concentrations of growth inhibit-ing elements in the soil. However, the use of theseamendments often makes soil borne plant nutrientsmore available or increases the soil’s ability to storemore applied nutrients. The most common agronomicorganic soil amendments are manure, compost, greenmanures, and sewage sludge. Other organic amend-ments not included in the list just mentioned are morecommonly or exclusively used for horticultural crops.The most common inorganic soil amendments are limeand gypsum. Soil acidifiers, such as sulfur, sulfuricacid, lime sulfur, ammonium thiosulfate, and ammo-nium polysulfide, may be used as well for agronomiccrops. Other soil acidifers, such as aluminum sulfate,are generally used for horticultural crops requiringacidic soils for optimum production.

The inorganic soil amendments, lime and gypsum,basically flood the cation exchange capacity of the soilwith calcium ions. Dolomitic limestone also providesmagnesium ions. These ions displace exchangeablesodium ions in sodic soils and exchangeablehydroxyaluminum ions in acidic soils. Lime proceedsfurther to neutralize the hydrogen ions released whilethe hydroxyaluminum ions are being reduced tounexchangeable aluminum hydroxide. This is theexchangeable hydrogen referred to in older explana-tions of soil neutralization with lime. Lime also neu-tralizes soil acidity caused by weak organic acids andammoniacal and urea nitrogen fertilizers.

Soil acidifiers acidify soils that either are alkaline ornot acid enough for the best production of the desiredcrop. Soil acidifers benefit forage crop production oncalcareous soils by lowering the soil pH to levelswhere iron, phosphorus, zinc, and manganese solubil-ity are increased enough to not limit production. Oncalcareous sodic soils that have native supplies ofcalcium (Ca), soil acidifiers cause enough calcium tobecome exchangeable to drive sodium (Na) off theexchange sites as well.

Irrigation water itself is a soil amendment when it isused to leach salts and sodium from the root zone. It

can be used alone on saline-sodic soils with soluble Cain the A soil horizon. It can also be the lone amend-ment if deep plowing or chiseling brings up Ca carbon-ate or sulfate (native gypsum) from the B and C hori-zons of a sodic B horizon soil.

Sodic soils have poor soil tilth because Na is a soildispersant. The soils when wet become puddled (noaggregation) having little pore space. They compactreadily and form hard surface crusts. which greatlyreduces their suitability as a plant growth medium.The addition of Ca to the soil acts as a soil flocculant.This causes clay sized particles to stick together toform aggregates. This increases soil permeability andaids the movement of water (irrigation or rainfall)through the soil profile to the depth Ca is incorporatedor released. This flushes the exchangeable Na down-ward through the soil profile. Adequate artificialdrainage must be in place to remove the Na irrevers-ibly from the root zone.

The economic feasibility of treatment depends uponthe value of the crops being grown and the amount ofexchangeable Na in the soil. Most often treatment withsoil amendments is done at smaller application ratesover a period of years rather than with one large singleapplication. The first application improves soil perme-ability and tilth to aid leaching of the sodium. The lateryearly applications then draw down exchangeable Naslowly over several years. The soil amendments maybe applied on sodic soils with the irrigation water,spread dry on the surface, or incorporated. In mostsituations surface applications of gypsum are moreeffective than incorporated applications. One excep-tion to this is on slick spots in humid areas, whereincorporation at depth and providing tile drains wasthe only effective technique.

Strongly sodic soils having more than 20 percent of theexchange capacity occupied by Na are expensive totreat. Calcium chloride or sulfuric acid can be used torapidly drop the amount of exchangeable Na on theexchange sites. A combination of calcium chloride andgypsum can reduce the cost of treatment and be nearlyas effective. However, forage crop production on thesesoils is not likely to pay for the cost of reclamation.

Particle sizes of applied gypsum and lime are impor-tant to their effectiveness short- and long-term. Gyp-sum should be a mix of finer and larger particle sizeswith an upper limit of 2 millimeters (10 mesh). This

Chapter 5



ensures that there are fine particles to quickly increasesoil permeability and large particles to sustain a con-tinuous release of Ca over time to keep exchangeableNa percentage low in the root zone. To be most effec-tive, lime should contain a mix of fine and largerparticle sizes: Fine ones to quickly raise the soil pH,and coarse ones to have some residual value. Manystates regulate the fineness of agricultural limestone.Generally, lime particles greater than 20 mesh are oflittle value in increasing soil pH while particles passingthrough a 60 mesh sieve are highly effective.

The other important factor with lime is its calciumcarbonate equivalent (CCE) rating. To meet the actualrate at which the soil test recommendation specifies,the CCE percentage of the lime material being appliedmust be known so that it is applied at the proper rate.For instance, a soil test recommended 2 tons of limeper acre to adjust the soil pH and the lime used hadonly a CCE of 80 percent. Then, 2.5 tons or 5,000pounds of that lime would be needed per acre.

Organic soil amendments are applied to increase soilorganic matter. This improves soil tilth by increasingthe number of water stable soil aggregates. It alsoimproves the cation exchange capacity of the soil andcreates a sink that holds nitrogen, phosphorus, andsulfur within the root zone as organic forms. As thisorganic matter slowly decomposes, these organicforms of plant nutrients are released for plant uptake.On sodic soils, organic matter incorporation improvessoil permeability and enhances the effect of appliedinorganic amendments, such as gypsum.

Many forage crops serve as green manure crops.Rather than being harvested for their feed value, theyare allowed to return to the soil unharvested to in-crease soil organic matter. This is done to benefitproduction of other crops following in the crop rota-tion. Allowing green manure crops to fully mature ismore effective in building soil organic matter thanterminating them at an early vegetative growth stage.The mature growth stage has more lignified material init and is more resistant to decomposition.

Manure and sewage sludge are the most commonlyapplied organic soil amendments to forage crops. Caremust be taken not to smother the forages with heavyapplications of these soil amendments. Excessiverates of application may also cause salt burn as well.

Both amendments should be applied at spring green-up or immediately after a harvest. This reduces thelikelihood of contaminating harvested forage andrenders it unfit for livestock feeding. Sewage sludgesshould be tested for their heavy metal concentrations.Applications of sewage sludge should be terminatedonce EPA or state regulated maximum soil loadingrates are approached. Soil tests for regulated heavymetals should be done each year sludge is to be ap-plied. Both of these amendments are stable organicmatter sources. Soils amended with these products forseveral years drop in organic matter content veryslowly once applications cease.

(f) Accelerating practice—Weedcontrol

Weeds are herbaceous plants growing in places wherethey are not wanted and interferring with the growthof the desired crop. They sometimes reduce its har-vested quality if allowed to remain. Weeds appearanywhere ground disturbance has taken place. Theyare pioneer species in plant ecological succession.They invade sites where competing vegetation hasbeen destroyed. It is not a matter of: Will they showup? It is a matter of: What will show up? Every timeforage crops are established, weeds will be present tocompete with them unless control measures are ap-plied. Forage crop stands that have declined will alsobe invaded by weeds as they thin out.

Weeds are broadly classified as grasses (includesgrass-likes) and broadleaves. This is important whenchoosing among selective herbicides. Some selectiveherbicides are excellent in controlling grassy weeds,but are ineffective in controlling broadleaves. Othersprovide excellent control of broadleaves, but aremostly ineffective in controlling grassy weeds. Otherherbicides may have broad spectrum control of sev-eral grassy and broadleaf weeds. Others are nonselec-tive and kill every actively growing plant. Herbicideselection should be based on those labeled for use onthe following:

• Forage crop being raised• Intended end use of the crop (pasture or stored

forage)• Anticipated weed type most likely to compete

with the forage crop



Chapter 5

Weed control is not so much a single practice, but atechnology area. Some of the other accelerating prac-tices already described help control weeds. Nutrientmanagement, liming, clipping, irrigation water man-agement, prescribed grazing, forage harvest manage-ment, and pasture and hay planting all have an impacton forage stand health that can keep weeds sup-pressed. Anything that gets a forage stand off to avigorous start and maintains a full canopy keepsweeds under control. The proper application of theseconservation practices reduces the need and relianceon chemical weed control in close sown forage crops.It will not eliminate entirely the need for chemicalweed control. Drought, insect and disease outbreaks,winter injury, human error, and other extreme envi-ronmental factors can often override the best efforts inmanagement. These stresses can thin or wipe outforage stands and give rise to a weed invasion.

Another classification of weeds distinguishes betweennoxious and non-noxious weeds. Noxious weeds arethose specified by Federal or State law as being espe-cially undesirable, troublesome, and difficult to con-trol. Examples would be Canada thistle, quackgrass,leafy spurge, horsenettle, Johnsongrass, and severalbindweeds and mustards. Each state that has a nox-ious weed law should have a noxious weed list in theNRCS field office technical guide. These weeds shouldhave picture identification and key distinguishingcharacteristics described for them. When giving onsiteplanning and application assistance to landowners, thepresence of noxious weeds should be brought to theirattention. Control measure options should be dis-cussed and documented in any conservation plansprepared for the land unit.

Besides chemical weed control, biological controls aresometimes appropriate for a targeted weed species.This type of weed control is generally not available tothe individual landowner. Federal laws prohibit theindiscriminate entry of exotic insects and diseases thatmight be hosted by a particular weed in its nativehabitat. Biological controls are extensively studied bygovernmental research agencies first and generallyapplied by governmental agencies. Great care must betaken not to introduce another pest that might get outof control. Biological weed control should not beconsidered a benign alternative to pesticides. Once abiological control is introduced to a new habitat, itcannot be easily gotten rid of if negative impacts arise.

The use of cultivating tools in controlling weeds inforage crop production is primarily limited to thosethat can be row cropped, such as corn or sorghumsilage. Spike toothed harrows, however, can be usedon established legume stands to kill annual weedseedlings without seriously hurting the legumecrowns. Primary tillage tools do control weeds tosome extent during seedbed preparation for both closesown and row crop forages. They kill existing weedsand newly germinated seedlings. Tillage tools may alsodilute weed seed counts if the previous crop wasweedy. They do this by mixing or inverting heavilyseeded surface soil with soil lower in the tilled zonethat has a lower seed count. Deep burial tends toprevent small seeded weeds from germinating. Largeseeded weeds, however, may be little affected. Ifburied below the effective depth of herbicide treat-ment, large seeded weeds, such as giant ragweed, mayescape herbicide control. Row cultivation can be usedon forage row crops with over the row banded herbi-cides. The cultivator keeps weeds under control be-tween the rows while the herbicide checks weedgrowth in the row. This cuts down on the amount ofherbicide needed for control of weeds over the entirefield.

Herbicide control of weeds can be done at varioustimes. The five times when herbicides can be appliedto forages are: preplant or preplant-incorporated,preemergence, postemergence, dormant, and betweencuttings.

Preplant-incorporated (PPI) applications aredone before planting the crop when conventionaltillage equipment is used to prepare the seedbed. PPIherbicides should be mixed into the first inch of soil.Preplant herbicides are used to kill weeds and existingforages for no-till seedings.

Preemergence herbicides are sprayed on the soilsurface after planting, but before seedling emergence.These herbicides are used on row crop forages, butnot on close sown ones.

Postemergence herbicides are used widely onforages to suppress weed competition during estab-lishment. They can be applied to legumes at ratherearly growth stages. On hay-crop grasses, post-emergence applications must be delayed until thegrass is at least 4 to 5 inches tall; at least 6 months forAlly.

Chapter 5



Dormant sprays are put on when the forages aredormant, but weeds are actively growing. These herbi-cides are nonselective and will kill the forages ifenough green leaf is available for herbicide uptake.

Spray applications between cuttings work similarlyto dormant sprays. Timing is essential and must bedone before significant forage regrowth occurs.

Whenever herbicides are used, crop use, field re-entry,harvest, and grazing restrictions must be adhered tostrictly to prevent contamination of people, foodsupply, and livestock. Mixing areas should be sited andconstructed to prevent surface or ground water con-tamination. Operators should wear appropriate protec-tive gear when mixing or applying chemicals andafforded washing facilities at the mixing and applica-tion site to decontaminate themselves or the protec-tive gear in case of exposure. Spray operations shouldbe conducted when wind velocities are low to preventdrift. They should not occur within a few hours ofpredicted heavy rainfall that could cause washoff andherbicide entry into watercourses. Sprayer tanksshould be rinsed, and the rinse water applied to thefield just treated. All chemical containers should betriple rinsed, and the rinse water placed in the sprayerand used on the target field. Dispose of containers asdirected on label. Strict adherence to all of this pre-vents contamination, illness, or death of people, non-target plants, or livestock and wildlife by needlessexposure to these poisons. Always follow the productlabel and local and state pesticide regulations.

To prevent herbicide resistance from developing inweeds, alternate chemicals with different modes ofaction in disrupting weed growth from one crop sea-son to the next. Herbicide modes of action to killweeds are cell membrane disrupter, fatty-acid inhibi-tor, growth regulator, photosynthesis inhibitor, pig-ment inhibitor, protein biosynthesis inhibitor, andseedling growth inhibitor. Also, the potential user canminimize need for herbicides by using the other con-trol methods mentioned.

Spray equipment should be under a preventativemaintenance schedule to prevent drift, irregular spraydelivery, and possible spill of herbicide. Each spraynozzle should be calibrated for correct delivery ofspray. Any nozzle not delivering the proper rate shouldbe replaced. Correct nozzle type selection for theapplication requirements is necessary.

(g) Accelerating practice—Diseaseand herbivory control

In actuality this is a dual technology area; it is beingdescribed under one title because the same principlesapply to both. Chemical control, cultural control usingpractices already mentioned, resistance breeding, andbiological control can keep diseases, insects, mites,nematodes, uninvited vertebrate herbivores, andmollusks from reducing forage production and qualityand shortening stand life.

Many organisms are covered under this dual technol-ogy area. They are diseases or pathogens that includeviruses, bacteria, fungi, and nematodes; arthropodsthat include insects and mites; mollusks that includeslugs and snails; and vertebrate herbivores that in-clude some birds and mammals, such as rodents,rabbits, and wild ruminants.

Resistance breeding has effectively reduced the sever-ity of disease outbreaks, nematode feeding, and insectattacks on forage crops. Thus planting varieties offorages resistant to locally important diseases, nema-todes, and insects is a viable cultural method to reducethe incidence of stand or yield loss.

Other cultural controls include conservation croprotations that break up life cycles of disease and insectpests, nutrient management, forage harvest manage-ment, irrigation water management, prescribed graz-ing, and control of weeds that act as alternate hostsfor other forage pests. Nutrient management producesforages that are more resilient to attack by disease andinsects. Forage harvest management may include earlyharvest to halt the spread of disease inoculum or takeaway the food source of the unwelcome herbivores. Italso includes cleaning harvesting equipment betweenharvests, mowing younger forage stands before olderones, maintaining a cutting schedule that keeps foodreserves high for rapid recovery, and mowing afterdew, rain, or irrigation water has dried on plants toprevent disease spread or outbreaks. Irrigation watermanagement can keep soils from being over-saturatedto prevent outbreaks of soil borne diseases that thriveunder waterlogged soil conditions. When a new forageseeding is being planned, select forage species that areadapted to the soil and climatic conditions at the site.This reduces the risk of a disease outbreak that arefavored under less favorable conditions. An examplewould be phytophthora root rot in alfalfa on restricted



Chapter 5

drainage soils. The timing of a forage planting canreduce slug damage. Depending on the climate, thiscan be either early spring plantings where adults donot overwinter or late summer plantings in warmer,drier areas when slug numbers and movement aresuppressed. Residue management can also reduce slugnumbers. All or a portion of the residue harboringslugs can be destroyed before planting to reduce theirnumbers. Exclusionary fencing, hunting, and trappingcan control vertebrate herbivores to various degrees.

Biological controls have had some good success onthe control of insects and other herbivores. Parasiticwasps and Bacillus thuringensis (Bt) are two ex-amples. Bt has been a spray insecticide product forsome time. Now the Bt gene is being spliced onto corngenetic material to control corn borer through plantbreeding. The corn plant produces its own insecticide.Parasitic wasps are being used to control alfalfa wee-vil. Where deer predation on corn silage seedlings ishigh, planting forage sorghum is alternative. It is notpalatable to deer. Insect pheromones are used to aid inthe detection, monitor the density of, and sometimesto disrupt the mating of insects. Pheromones arechemical attractants released by female insects toattract a male. Pheromone traps are used to checkinsect populations. Point sources of pheromonesplaced about a field confuse male insects and keepthem from finding female mates. This is effective onlywhen the larvae produced by this mating cause theeconomic damage to the forage crop. However, thiscontrol method is expensive and not always effective,especially if it attracts more females to the field.

Chemical controls should be applied only if none ofthe other approaches have proven effective or timely.As with herbicides, care must be taken not to contami-nate or poison nontarget species or areas with bacteri-cides, fumigants, fungicides, insecticides, miticides,nematicides, and rodenticides. Crop use, field re-entry,harvest, and grazing restrictions must be adhered tostrictly to prevent contamination of people, foodsupply, and livestock. Mixing areas should be sited andconstructed to prevent surface or ground water con-tamination. Operators should wear appropriate protec-tive gear when mixing or applying chemicals andafforded washing facilities at the mixing and applica-tion site to decontaminate themselves or the protec-tive gear in case of exposure. The appropriateness ofthe protective gear is based on the toxicity of the

chemical and its formulation. Follow label instruc-tions. Formulation types are emulsifiable concentrate,solution, flowable, wettable powder, dry flowable,soluble powder, invert emulsion, dust, granule, pellet,microencapsulate, and water-soluble packet. Formula-tion selection is also influenced by the forage cropbeing protected, its proximity to water sources, humanhabitation, and other sensitive areas, the availableapplication machinery suitableness to deliver it prop-erly, and cost considerations. Spray operations shouldbe conducted when wind velocities are low to preventdrift. They should not occur within a few hours ofpredicted heavy rainfall that could cause washoff andpesticide entry into watercourses. Sprayer tanksshould be rinsed, and the rinse water applied to thefield just treated. All chemical containers should betriple rinsed, and the rinse water placed in the sprayerand used on target field. Dispose of containers asdirected on label. This prevents contamination, illness,or death of people, non-target plants and animals, orlivestock by needless exposure to these poisons.

To prevent pests from developing resistance to chemi-cal control, rotate chemicals with different modes ofaction. Fungicide combinations are also effective inkeeping resistance from building up in the fungi beingtreated. The use of other control methods beforeresorting to chemicals also extends the useful life ofchemicals.

The combination of different control methods is calledintegrated pest management (IPM). It attempts to findthe most effective, lowest cost, and least environmen-tally hazardous combination of pest control methods.Key principles for IPM in forage pest management are:

• Avoid killing off beneficial species when trying tosuppress a pest.

• Take advantage of natural suppression throughcrop management practices that favor the foragecrop’s health, encourages natural predators, orboth.

• An ounce of preventive control is worth a poundof responsive control.

• If preventative cultural measures fail, resort to aresponsive control only when the pest densityreaches the economic threshold warranting theexpense of the control measure.

• Pests are likely to overcome plant resistance andpesticide control measures with time throughnatural selection and evolution.

Chapter 5



Components of an effective forage crop IPM programare the following:

• Recognize that most noncrop organisms in aforage crop field help maintain a favorable cropenvironment and should not be sacrificed to killoff the target pest.

• Correctly identify the offending pest. This hastwo aspects. Make sure you have the real of-fender and not just a symptom of underlyingdeeper problem. Then make sure to correctlyidentify the organism so that the treatmentselected is effective in its control.

• Know at what stage of the pest’s life cycle orwhat time of the year the pest will do the mostdamage to the forage crop.

• Use preventative measures whenever possible byanticipating which pests are most likely to be aproblem. This will avoid a pest build-up in thefirst place.

• Scout for pests regularly to detect their presenceand build-up. Early detection can result in pro-jections on when pest damage will peak andindicate an effective, least cost treatment option.

• Evaluate past performance of pest control strate-gies to see if more viable control alternatives areneeded. Field records are essential to this com-ponent. Timing of control measures can beevaluated with good records. The control mea-sure itself may not be the problem, but the timeor care at which it was applied is.

• Monitor new product development to employnew viable control options as they come on-line.

(h) Facilitating practice—Conservation crop rotation

This practice is mentioned last because it is greatlyinfluenced by all the other practices mentioned previ-ously along with the land unit’s animal forage and feedrequirements, resource base, and its position in awatershed. Refer back to figure 5–39. As much as iseconomically feasible, a conservation crop rotationplan for the land unit should strive to meet the live-stock forage and feed requirements being raised there.This is a decision that only the land unit manager canmake. It should be based on an economic analysis ofthe land unit’s costs of production versus purchasingforage and concentrates from off-farm sources. Themore diversified the crops are, the more farm machin-ery and feeding equipment generally are needed.

Because many livestock-rearing operations are sitedon marginally productive lands, there may be environ-mental as well as good economic reasons to purchasefeed or forage. Row crop forage and feed grain pro-duction may cause undue soil loss or water qualityproblems downstream. Even with the best conserva-tion plan that corrects the environmental problems, itstill may not be economically practical to raise only afew acres of a crop that requires a different set ofmachinery and storage facilities.

Conservation crop rotation is a facilitating practice onlivestock-rearing operations in that it attempts tosatisfy livestock forage and feed requirements for theproduction year. This is especially true where live-stock do not have access to a dependable year-longsource of grazable forage. It is also true on livestockfarms or ranches where complementary pastures oncropland improve weight gain over that obtained bynative rangeland or permanent pasture. This is not tosay that the crop rotation plan for the farm should notdictate at least to some extent the number of livestockbeing raised on the land unit. However, the conserva-tion planner must be cognizant of two things:

• The land unit manager or the financial advisorhave probably established a herd size that meetsa financial objective based on expected outputand commodity price.

• Most land units have not reached their full pro-ductive potential so there is room for forage andfeed production improvement. There are excep-tions to this generalization. However, thoseexceptions need only limited assistance fromNRCS.

Conservation crop rotation also facilitates the estab-lishment of a more diverse set of crops, forages, orothers. Generally, this is done on livestock farms andranches to improve yields or feed quality, or both,where grazing land resources are limiting livestockoutput goals.

The design of a conservation crop rotation plan for thelivestock-rearing land unit having cropland along withpastureland or hayland, or both, uses must serve manypurposes. (Pasture referred to here includes all landuses grazed by livestock.)



Chapter 5

(1) Livestock forage and feed

The crop rotation should strive to produce its portionof the livestock forage and feed requirements to bemet by home grown crop production. This is estab-lished by the land unit manager. This decision can beinfluenced by pointing out alternative off-farm feedsources or livestock ration substitute feedstuffs.Perhaps increasing time on pasture by using grazablecrop residue, forage aftermath, or supplementarycropland pasture and reducing stored feed and forageproduction are options to explore.

The rotation should meet the forage and feed require-ment expected from it each production year. Thismeans coordinating different crop rotations based ondifferent fields’ capability to produce crops withoutdegrading the soil, water, and air resources associatedwith the land unit. Ideally, production targets for eachcrop are met each production year. This is done byscheduling the different rotations around the differentfields to yield a similar amount of acres producingeach crop every year. These are based on long-termaverage per acre yield projections times the averageacreage each crop occupies on all the croplandthrough the longest rotation cycle.

Example 5–3 shows a crop rotation worksheet. It wasidealized to come out with the same acres for eachcrop every year. Ordinarily, some year-to-year differ-ences in acreage occur, but they should not be widelydisparate. To arrive at these yield projections, eachfield must be given an estimated yield of each cropbased on the forage suitability group potential toproduce it and the accelerating conservation practicesapplied that move yields toward that potential. Referto figure 5–39 to conceptualize this procedure. A croprotation plan worksheet is developed that lists all cropfields and their subunits contributing to the livestockforage and feed demand requirement. Their acreage islisted, and the rotation sequence follows one crop at atime for each production year projected out from thetime the conservation plan is prepared or updated. Thelength of the crop rotation, the number of years thecrop remains in the rotation, and the number of cropsgrown simultaneously each year determine how manyacres of a particular crop are growing on the field inany given production year.

Additional forage acreage may round out the rest ofthe forage needed to meet livestock demand. This maycome from hayland or pasture, or both. All of this is

detailed in a complete forage-livestock balance orinventory sheet. Production estimates by field may beincluded on the crop rotation worksheet or on theforage-livestock balance or inventory worksheet, orboth. The number of different crop rotations should bekept to a minimum. If not, the worksheet becomesdifficult to fill out and the producer has an even hardertime trying to follow it. The number of different rota-tions can be kept low by stringing along enough con-servation practices to meet soil loss and water qualitygoals while still meeting forage and feed productiontargets. In example 5–3, for instance, fields 2 through 4may be contour stripcropped fields with different KLSsoil loss ratios. To keep the same 6-year rotationwithout exceeding soil loss tolerance values, differentresidue management practices might be employed, no-till on one field and perhaps mulch till on another.Another option might be to construct a diversionterrace at midslope at a contour strip boundary on oneof the fields with a high KLS value.

(2) Soil loss

Conservation crop rotations must meet soil loss objec-tives from wind or water erosion. Currently, the Re-vised Universal Soil Loss Equation is used to estimatepresent water erosion rates based on current manage-ment (benchmark) and future erosion rates based onalternative conservation management systems. Theland manager selected alternative conservation man-agement system becomes the planned conservationmanagement system. The crop rotation for a particularfield being evaluated is then set until a revision be-comes necessary. The Wind Erosion Equation is usedto estimate soil loss by wind erosion in similar fashionto water erosion prediction. This procedure is de-scribed in the current National Agronomy Manual.

(3) Soil organic matter and tilth

Conservation crop rotations can be designed to in-crease or restore soil organic matter and tilth. Close-growing forage crops with their large, well-distributedroot biomass can increase organic matter and thepercentage of water stable aggregates within 2 to 3years. Soils that tend to lose their structure within aseason or two, benefit by crop rotations that reintro-duce a close-sown forage crop back within 2 to 3years. Conservation crop rotations may also include acover crop that grows between production crops.Cover crops add organic biomass to moderate theeffect that low residue production crops have onlowering soil organic matter content and percentage of

Chapter 5



Example 5–3 Crop rotation worksheet

Given: A continuous corn silage field and three other fields that have a 6-year rotation. The 6-year rota-tion consists of 2 years of corn silage followed by a year of small grain and 3 consecutive years ofhay. They are systematically scheduled to produce the same acreage of a crop each productionyear. The 40 acres of corn silage, 10 acres of small grain, and 30 acres of hay from the croplandmeet the desired amount of feed and forage from the cropland acres.

Crop Rotation Worksheet

Field number

Total

Crop

Summary

Coop. Name

Tract number

Acres Crop

Year

12A2B3A3B4A4B

20101010101010

Corn silageSmall grainHayTotals

CSHYSGHYCSHYCS

40103080

40103080

40103080

40103080

40103080

40103080

40103080

40103080

CSCSHYHYSGHYCS

CSCSHYCSHYHYSG

CSSGHYCSHYCSHY

CSHYCSSGHYCSHY

CSHYCSHYCSSGHY

CSHYSGHYCSHYCS

CSCSHYHYSGHYCS

80



Chapter 5

water stable aggregates. In example 5–2, for instance,the corn silage entries might have also included asymbol after a slash mark indicating that a cover cropfollowed the harvest of corn silage. Cover crops arenot harvested and generally are killed before seed set.If the crop is harvested, it is just another productioncrop and reflects a double or multiple crop productionsequence during a production year. Many forage cropscan serve as cover crops. Notable examples are tallfescue in tobacco crop rotations; red clover, alsikeclover, and timothy in potato crop rotations; andannual ryegrass and various clovers in corn silage croprotations.

(4) Nutrient management

Conservation crop rotations can be designed to useand hold nutrients from leaching or runoff loss as theyare applied through manures or fertilizers or fixed bylegumes in the rotation in the case of nitrogen. Referback to the nutrient management practice sectionwhere crop rotation nutrient balancing is described.This can help achieve downstream water quality goalsby minimizing or eliminating nutrient runoff or loss toground water. Cover crops again may be worth includ-ing in the crop rotation to use nutrients that mightotherwise leach below the root zone while no produc-tion crop is actively taking up leachable nutrients. Thisworks best in humid areas of the United States thathave a substantial cool-season growing period after aproduction crop is harvested and before the next oneis planted. There also must be a period where rainfallis in excess of the root zone's water holding capacityso that nitrogen, and sometimes phosphorus, wouldleach below the root zone if it were not for the covercrop. Cover crops also provide additional groundcover after low residue crop production. Runoff loss ismitigated under a conservation crop rotation by pro-viding sufficient ground cover, soil structure, andcanopy cover to intercept and infiltrate most precipita-tion and irrigation water received. Crop rotations canalso resupply nitrogen stores in soils when legumecrops are included in them. Crop rotations with le-gumes in the rotation should have crops following thelegumes that have the highest nitrogen need of all inthe rotation.

(5) Manipulate plant available water

Conservation crop rotations can also be used to ma-nipulate plant available water in areas where a waterbudget must be closely watched to produce adequatecrop yields from year to year. Crops may be sequencedthat do not interfere with each other’s plant availablewater needs. This may include leaving part of the fieldfallow to restore plant available water for a crop in theensuing year. Generally, low water demand plants arerotated with crops that have a higher water demand.They may exploit water from different rooting depths.This function also can be used in saline seep rechargeareas by using crops, such as alfalfa, to use up soilwater so that deep percolation is reduced or halted.This helps to prevent saline seep areas from occurringat lower elevation points. Refer to figure 3–4 in chap-ter 3 (page 3–78) for examples of saline seep forma-tion. Note position of recharge areas and their relativeproximity to the seep area itself.

(6) Break up pest cycles

Conservation crop rotations can also be used to breakup pest cycles. This includes certain weeds, diseases,and insects. Crop rotations that include row crops,small grains, and forages restrict annual weed popula-tions greatly. The growing conditions never last longenough for a particular weed to become abundant anddominant. Many forage crops work well as smothercrops. Smother crops establish quickly and form adense canopy that shades out other plants. Alfalfa,foxtail millet, ryegrass, and sudangrass are examples.Leaf diseases, such as scab, take-all, and cephalospo-rium stripe in small grains, are controlled well by croprotation. Corn rootworm is an insect that can becontrolled quite effectively by crop rotation. Care mustbe taken in formulating crop rotations not to introducean alternate host immediately before or after a cropthat you are trying to protect from a pest with thispractice. It is also important not to replant the samecrop too soon after being in the crop rotation earlier.Some carryover of the insect or disease pest mayresult in a serious reinfection and an economic losswithout responsive treatment. Alfalfa seedings benefitby being in a crop rotation that kills off all previouslygrowing alfalfa plants so that new seedlings are notsubject to allelopathic substances in the tissue of theold plants.

Chapter 5



(7) Species selection

While setting crop rotation lengths and the portion ofthe time forages occupy the rotation, work with theproducer to determine which forages best meet theirneeds for forage production and will persist for thetime needed in the rotation. This is not terribly impor-tant if an annual forage crop will be planted each yeardesignated to fill the forage portion of the crop rota-tion. However, if the producer does not want to reseedannually, then it becomes more critical which species,set of species, or cultivars of the species selected areused. If the forage crop is only to last 2 consecutiveyears in the crop rotation, a biennial forage crop or ashort-lived, inexpensive seed source perennial mightbe appropriate. If the forage crop is going to persist inthe rotation for 2 or more years, long-lived perennialsshould be selected that has good disease and insectresistance and is climatically adapted to the site. Theharvest regime should be adjusted to a less frequentcutting schedule for longer stand survival as the timein the rotation lengthens. Care must be taken not toschedule a forage to last longer in the rotation thanthat realistically possible because of local climaticconditions and insect and disease problems. An ex-ample of this is where clover root curculio feeding andFusarium root rot infection combine to decreasealfalfa survival steadily and create an uneconomicstand within 2 to 3 years.

600.0508 Conclusion

With this management section guidance for foragecrop and pasture lands, state specialists should pre-pare more specific guidelines for field office personnelto use in planning and applying resource conservationpractices. Several land grant universities produceagronomy manuals or guides that give more specificrecommendations than can be placed in a nationalpublication. Seeding rates, seeding mixtures, stubbleheights, irrigation rates and scheduling, noxious weedlists, and recommended species and cultivars are justa few of the more specific details needed to have acomplete field office technical guide or ready refer-ence. As much as possible this material should becondensed into tables or charts that are easily readand understood. Design procedures should be formal-ized, readily followed, and placed on job sheets.Simple fill-in-the-blank entries should be provided onthe job sheets. The job sheets can be electronic orpaper copies.

The reader is directed to Chapter 4, Inventory andMonitoring Grazing Lands Resources, which givesguidance on creating an inventory of a land unit’sresources. This is done to see how pasture and foragecrop production can be integrated to feed the livestockon the land unit in the most efficient way. Basic to theinventory is an assessment of the soils on the landunit. This is done using the forage suitability groupsdeveloped in your state as described earlier in thishandbook. Once the inventory for the land unit isdone, conservation planning options using the tech-niques described in chapter 11 are weighed and dis-cussed with the land manager. Many of the conserva-tion practices described in this chapter will make upthe final resource conservation plan. Chapter 6, Live-stock Nutrition, Husbandry, and Behavior, gives in-struction on fulfilling the needs of the livestock raisedon the land unit. The practices contained in the con-servation plan must meet their needs efficiently andeconomically.





Lands

Section 2 Managing Forage Crops and Pasture

Lands

Exhibits

Ch

. 5 S

ectio

n 2

Ex

hib

its





Lands

Section 3 Procedures and Worksheets for

Planning Grazing Management

Ch

. 5 S

ectio

n 3

Chapter 5

5.3–i(190-vi, NRPH, September 1997)


Section 3 Procedures and Worksheets for Planning

Grazing Management

Contents: 600.0509 General 5.3–1

(a) Calculating stocking rates ........................................................................ 5.3–1

(b) Harvest efficiency ...................................................................................... 5.3–1

(c) Adjustment factors used to determine stocking rate ............................ 5.3–1

600.0510 Forage inventory 5.3–2

(a) Based on trend, health, and utilization ................................................... 5.3–2

(b) Based on production data and growth curves ....................................... 5.3–2

(c) Stocking rate determinations ................................................................... 5.3–2

(d) Forage value rating method ...................................................................... 5.3–3

600.0511 Animal inventory 5.3–5

Tables Table 3–12 Adjustments for slope on rangelands 5.3–1

Table 3–13 Adjustments for water distribution on rangelands 5.3–1

Exhibits Exhibit 5–1 Worksheet—Forage Inventory Based on Current 5.3ex–1

Stocking Rate, Trend, Health, and Utilization

Exhibit 5–2 Worksheet—Forage Inventory 5.3ex–5

Exhibit 5–3 Worksheet—Stocking Rate and Forage Value Rating 5.3ex–9

Exhibit 5–4 Worksheet—Determining Forage Composition and 5.3ex–13

Value Rating

Exhibit 5–5 Worksheet—Livestock Inventory and Forage 5.3ex–17

Balance

Exhibit 5–6 Worksheet—Prescribed Grazing Schedule 5.3ex–21

Chapter 5


Management of Grazing Lands National Range and Pasture HandbookSection 3 Procedures and Worksheets forPlanning Grazing Management

600.0509 General

(a) Calculating stocking rates

Determining the grazing capacity of an area can becomplex and confusing and is the main factor affectingthe success of a prescribed grazing strategy. The taskof determining the amount of air dry weight of thecurrent year’s standing crop is often variable andunpredictable. Adding to the complexity are speciesquality, quantity, and distribution. Stocking rate isdefined as the amount of land allocated to each animalunit for the entire grazable period of the year. Rates ofstocking vary over time depending upon season of use,climate variations, site, and previous and currentmanagement goals. A safe starting stocking rate is anestimated stocking rate that is fine tuned by the clientby adaptive management through the year and fromyear to year.

(b) Harvest efficiency

Harvest efficiency is the percentage of forage actuallyingested by the animals from the total amount offorage produced. Harvest efficiency increases as thenumber of animals increases in an area and theyconsume plant material before it senesces, transfers tolitter, or otherwise leaves the area. Continued season-long grazing or increased stocking rates can eventuallydecrease forage intake and forage production per unitarea.

(c) Adjustment factors used todetermine stocking rate

Adjustments in stocking rates should be consideredfor areas that are not grazed by livestock because ofphysical factors, such as difficulty of access (slope)and distance to water. The adjustments should bemade only for the area that is considered necessary forreduction of the animal numbers. For example, 40percent of a management unit may have 30 percentslopes; therefore, the adjustment is only calculated for40 percent of the unit. Distance to drinking water alsoreduces grazing capacity below levels indicated byforage production. Local guides should be developed

for use in inventorying and determining safe startingstocking rates. Local guides should also contain ad-justments for different kinds and classes of livestock.Table 3–12 gives example adjustments for slope onrangelands, and table 3–13 gives example adjustmentfor water distribution on rangelands.

Table 3–12 Adjustments for slope on rangelands(example only)

Percent slope Percent adjustment

0 – 15 0

15 – 30 30

31 – 60 60

> 60 100

Table 3–13 Adjustments for water distribution onrangelands (example only)

Distance (miles) Percent adjustment

1/2 to 1 0

1 to 2 50

2 to 3 75



600.0510 Forage inventory

(a) Based on trend, health, andutilization

Often the best method for establishing the initialstocking rate is to assist the client in making a trendstudy and utilization check on the key grazing area ofthe management units (see exhibit 5–1). A recording ofcurrent stocking rate along with an evaluation of trendor health of the plant community and percent use ofthe key species can provide an insight to the correctstocking rate for the grazing period. Considerationshould be given for the past and current growingconditions. Together, these evaluations can be used bythe client to determine if stocking rate for the grazingunit has been too high, low, or correct for the grazingperiod. Following this analysis, the client can readilyobserve and make a decision on correct stocking ratesas well as future management needs. After the annualstocking rate is determined, projected production bythe day, week, month, or season can be determined byapplying growth curve factors (see exhibit 5–2). Pro-duction from each management unit is then totaled todetermine an estimated initial stocking rate for theoperating unit.

(b) Based on production data andgrowth curves

Another method of establishing the initial stockingrate is based on production data and growth curvesdeveloped locally as a part of the field office technicalguide. An estimate of forage supply can be estimatedfor each month and totaled for the annual productionfor each management unit. The forage supply for eachseparate month can be totaled to provide a monthlytotal production for the entire operating unit as well asa total production for the operating unit (exhibit 5–2).Monthly and annual production can then be comparedto the monthly forage needs of the animals to deter-mine months of surplus and deficient forage supply.

The spread sheet should be designed to accommodatethe necessary identification of response units occur-ring in the management units. Response units aredistinguished from each other based on their ability toproduce useable forage. Normally, consideration isgiven to:

• range ecological sites,• similarity index,• pastureland and hayland suitability groups and

fertilization rates,• pastureland and hayland species,• forest ecological sites,• transact data,• plant vigor,• adjustment factors resulting from accessibility,

such as distance to water or elevation change• harvest efficiencies resulting from grazing man-

agement scheme, and• barriers that restrict travel to parts of the man-

agement unit.

Forage supply is determined for each of the responseunits (ecological site and similarity index, foragesuitability group) and totaled to determine the produc-tion for the management unit (pasture or field). It canbe expressed as production per day, week, month, orseason, and totaled for the year.

Production for the operating unit is then determinedby totaling the production of each management unit.This is expressed as daily, weekly, monthly, annual, orseasonal totals. The forage inventory should be devel-oped to adequately express the forage production toallow the necessary detail of planning for grazingmanagement.

(c) Stocking rate determinations

(1) Usable production method

This method of determining stocking rates is based onmeasuring or estimating the total amount of forage(standing crop) per acre and converting green weightto air dry weights and into AUM’s. Air dry conversionfactors can be determined by using conversion tablesbased on forage species or similar habit groups andstage of growth (see chapter 4, exhibit 4–2).

Chapter 5



The only production to be considered in determiningstocking rate is the current year’s forage growth below4.5 feet vertical height. Forage from plant species thatare undesirable, nonconsumed, or toxic to the kindand class of livestock intended to graze the areashould be excluded. The air dry weight is summarizedfor the entire area to be grazed after any necessaryadjustments are made.

The amount of forage available for consumption ismultiplied by the harvest efficiency expected for thearea. This is the amount of forage allocated for theanimal’s consumption. This amount is then divided bythe amount of forage allocated to an animal unitmonth (AUM). This gives the number of animal unitmonths the area can safely support if the estimated orexpected forage production occurs. Formula 5–1 at thebottom of this page is an example of the calculation todetermine the stocking rate for an area that is produc-ing 2,000 pounds per acre of total annual forage pro-duction.

To arrive at the total AUM's for that management unit(pasture), the AUM’s per acre are multiplied by thenumber of acres represented by each level of produc-tion.

(2) Forage preference method

This is a method to determine stocking rate is basedon consumption of forage allocated by preference ofanimal species and the competitive relationship be-tween animal species. On rangeland, the Multi-SpeciesCalculator in GLA calculates this precisely. It alsocalculates average harvest efficiency for the plantcommunity selected. See exhibit 5–3 for guidance inmaking these calculations.

(d) Forage value rating method

Forage value is a utilitarian classification indicatingthe grazing value of important plant species for spe-cific kinds of livestock or wildlife. The classification isbased on palatability or preference of the animal for aspecies in relation to other species, the relative lengthof the period that the plant is available for grazing, andnormal relative abundance of the plant. The five foragevalue categories recognized are:

• Preferred plants• Desirable plants• Undesirable plants• Nonconsumed plants• Toxic plants

(1) Preferred plants

These plants are abundant and furnish useful foragefor a reasonably long grazing period. They are pre-ferred by grazing animals. These plants are generallymore sensitive to grazing misuse than other plants anddecline under continued heavy grazing.

(2) Desirable plants

These plants are useful forage plants, although nothighly preferred by grazing animals. They either pro-vide forage for a relatively short period or are notgenerally abundant in the stand. Some of these plantsincrease, at least in percentage, if the more highlypreferred plants decline.

(3) Undesirable plants

These plants are relatively unpalatable to grazinganimals or are available for only a very short period.They generally occur in insignificant amounts, but maybecome abundant if more highly preferred species areremoved.

[5–1]2 000 25 500

500

79063 1 58

, / .

. / . /

lb ac

lbAUMs ac or ac AUM

× ( ) =

( ) =

harvest efficiency lb forage consumed

lb forage for 1 animal unit for 1 month



(4) Nonconsumed plants

These plants are unpalatable to grazing animals, orthey are unavailable for use because of structural orchemical adaptations. They may become abundant ifmore highly preferred species are removed.

(5) Toxic plants

These plants are poisonous to grazing animals. Theyhave various palatability ratings and may or may notbe consumed. They may become abundant if unpalat-able and if the more highly preferred species areremoved.

These ratings are used in the determination for under-story stocking rates for grazed forest. The amount andnature of the understory vegetation in grazed forestare highly responsive to the amount and duration ofshade provided by the overstory canopy. Significantchanges in the kinds and abundance of the plantsoccur as the canopy changes, often regardless of thegrazing use. Some of the changes occur slowly andgradually as a result of normal changes in tree size andspacing. Changes following intensive woodland har-vest, thinning, or fire may occur dramatically andquickly. For these reasons the forage value ratings ofgrazed forest are not an ecological evaluation of theunderstory as is used in the range similarity indexrating for rangeland. This is a utilitarian rating of theexisting forage value of a specific area of grazedforest. These ratings are based on the percentage, byair dry weight, of the existing understory plant com-munity made up of preferred and desirable plantspecies. Four value ratings are recognized:

Forage value rating Minimum percentage

Very high 50 preferred + desirable = 90

High 30 preferred + desirable = 60

Moderate 10 preferred + desirable = 30

Low Less than 10 preferred

To achieve a given forage value rating, first achieve thepercentage preferred. Add the percentage desirable. Ifthe required total percentage of preferred and desir-able are not achieved (90, 60, 30), reduce the foragevalue rating to the next lowest rating. Very high foragevalue rating for a given animal species requires that atleast 90 percent of the plant composition is ratedpreferred and desirable, with at least 50 percent beingpreferred. High forage value rating requires a total of60 percent preferred and desirable with at least 30percent being preferred.

The production of the understory plant can varygreatly even within the same canopy class. Foragevalue rating must always consider the production ofair dry forage when determining stocking rates. Intro-duced perennial species are considered preferred ordesirable plants if they are adapted and produce highquality forage. Exhibit 5–4 is a grazable woodland siteguide that uses canopy class and forage value ratingsand suggested stocking rates.

Exhibit 5–3 describes in detail the calculations fordetermining stocking rates based on preferences offorage plants by specific animal species. These calcu-lations should be used for establishing safe startingstocking rates for each forage value rating on a givensite.

Chapter 5



600.0511 Animal inven-tory

An inventory of the domestic animals occupying orplanned to occupy the operating unit must be devel-oped. This animal inventory should be separated intoto the necessary herds to allow the desired husbandryto be practiced. This is generally by kind, breed, class,and age. If a management unit is critical to a particularherd, it should be noted. The number of livestock isshown in each management unit to be grazed by theday, week, month, or season, and a total is given sothat the forage demand can be planned in relation toforage production.

Herbivorous wildlife numbers should be determinedby management unit, and their forage requirementsexpressed in the same manner as the livestock. If theyare migratory, such as elk, determine the time they areexpected in the management unit.

The animal inventory is used in combination with theforage inventory to balance the forage supply with thedemand (see exhibit 3–5).





Lands

Section 3 Procedures and Worksheets for

Planning Grazing Management

Exhibits

Ch

. 5 S

ectio

n 3

Ex

hib

its

Chapter 5

5.3ex–1(190-vi, NRPH, September 1997)

Management of Grazing Lands National Range and Pasture HandbookExhibit 5–1 Worksheet—Forage Inventory Based on Current Stocking Rate, Trend, Health, and Utilization

Forage Inventory Based on Current Stocking Rate,Trend, Health, and Utilization

(Method For Determining Fixed Stocking Rate)

Cooperator: _____________________ Technician: _______________________ Date: ____________

Percent use

Current stocking rate of key Selected stocking rate

Pasture Acres Au Mo. Aum Trend Species Au Mo. AUM

Total XXXX XXX XXXX XXXXX XXX XXXX

Notes:


5.3ex–2 (190-vi, NRPH, September 1997)

Exhibit 5–1 Worksheet—Forage Inventory Based on Current Stocking Rate, Trend, Health, and Utilization—Continued

Instructions forForage Inventory Based on Current Stocking Rate,

Trend, Health, and Utilization

1. Cooperator’s name.2. Technician’s name.3. Date of completion of the inventory.4. List the pastures or fields to be inventoried.5. Enter the acres in each of the pastures or fields listed.6. Record the animal unit equivalents normally stocked in each pasture.7 Record the number of months the animals listed in item 6 are in each of the

pastures.8. Multiply item 6 times item 7 and record the product. This is the number of

animal unit months with which the pasture has been stocked.9. Record the apparent trend of the vegetation in the pasture.

10. Record the expected percent utilization of the key grazing species in each of the pastures.

11. After evaluating the apparent trend and the percent use of the key specieswith the land manager, record the animal unit equivalents the land managerthinks is needed to ensure an upward trend and proper management of thekey species.

12. Record the number of months the animal will be in the pasture.13. Multiply item 11 by item 12 and record the product. This is the animal unit

months of grazing that it is estimated that the pasture will produce for theanimals being evaluated.

14. Record the total acres being evaluated in all pastures.15. Record the total animal unit months that represents the current stocking

rate for all of the pastures being evaluated.16. Record the total animal unit months that is the new recommended safe

starting stocking rate for the area evaluated.17. Record any notes of explanation needed for understanding evaluations or

needed followup.

Chapter 5


Management of Grazing Lands National Range and Pasture HandbookExhibit 5–1 Worksheet—Forage Inventory Based on Current Stocking Rate, Trend, Health, and Utilization—Continued

Example – Forage Inventory Based on Current Stocking Rate,Trend, Health, and Utilization

(Method For Determining Fixed Stocking Rate)

Cooperator: (1) (2) Technician: Date: (3)

Percent use

Current stocking rate of key Selected stocking rate

Pasture Acres Au Mo. Aum Trend Species Au Mo. AUM

(4) 1 (5) 320 (6) 20 (7) 12 (8) 240 (9) - (10) 60 (11) 16 (12) 12 (13) 192

2 640 28 12 336 0 40 32 12 384

3 320 40 6 240 - 60 36 6 216

4 320 40 6 240 + 50 40 6 240

Total (14) 1600 XXXX XXX (15) 1056 XXXX XXXXX XXX XXXX (16) 1032

Notes: (17)

Chapter 5



Ex

hib

it 5

–2

Wor

kshe

et—

For

age

Inve

ntor

y

Fo

rag

e In

ven

tory

Co

op

erat

or:

Tec

hn

icia

n:

D

ate:

Pas

ture

Kin

d o

f F

ora

ge

and

Pro

du

ctio

nF

acto

rs &

HE

Acr

es

Pro

-d

uc-

tio

nA

UM

/AC

rate

w/o

adj.

AU

MT

ren

dA

dj.

fact

or

To

tal

AU

M

(12

) MO

NTH

S

XXXX

XXXX

XXXX

XXXX

XXX

Not

es:

Sto

ckin

g



Exhibit 5–2 Worksheet—Forage Inventory—Continued

Instructions for Forage Inventory

1. Enter name of the client.2. Enter name of the person providing assistance to client.3. Enter date of assistance.4. Record the name and/or number of the pasture or field.5. Record the information needed to reflect the production level.

(note: HE = harvest efficiency)6. Record the acres in each management unit or response unit located in each

management unit.7. Record the expected animal unit months production per acre for the entire

growing season.8. Multiply item 6 times item 7 and record the product. This is the estimated

AUMs of production without adjustment for trend, vigor, or someunaccounted reason.

9. Record the current trend or apparent trend of the plant community.10. Record the needed adjustment to the stocking rate in item 8 to reflect the

reduced production or harvest efficiency for which you have not accounted.This should be a number that represents the percentage of total productionin item 8 that will be available.

11. Multiply item 10 times item 8 and record the product. This is the AUMs estimated to be produced on the response unit or management unit.

12. Record the abbreviations for the months above the 12 columns. You may record these starting with any month to best reflect the growing and grazing seasons in your area.

13. Record the AUMs produced each month. This is calculated by multiplyingthe percentage produced each month times the total AUMs recorded in item11.

14. Record the name indicating the area being inventoried.15. Record the total acres inventoried.16. Record the total AUMs produced on the area inventoried.17. Record the total AUMs produced on the area inventoried by month.18. Record information concerning purchase or harvest of hay.19. Record information concerning the purchase or securing of protein

supplement.20. Record the AUMs of hay purchased or harvested.21. Record AUMs of protein if applicable.22. Record any explanation needed to understand the forage inventory.

Chapter 5



Ex

hib

it 5

–2

Wor

kshe

et—

For

age

Inve

ntor

y—C

onti

nued

Exa

mp

le –

Fo

rag

e In

ven

tory

Co

op

erat

or:

Tec

hn

icia

n:

D

ate:

)

Pas

ture

Kin

d o

f F

ora

ge

and

Pro

du

ctio

nF

acto

rs &

HE

Acr

es

Pro

-d

uc-

tio

nA

UM

/AC

rate

w/o

adj.

AU

MT

ren

dA

dj.

fact

or

To

tal

AU

M

(12

) MO

NTH

S

XXXX

XXXX

XXXX

XXXX

XXX

Not

es:

794

AU

M =

66

AU

(1)

(2)

(3

(4)

(6)

(7)

(8)

(9)

(10)

(11)

(13)

(14)

(15)

(16)

(17)

(18

)(2

0)

(19

)(2

1)

(22

)

Ranc

h

Sto

ckin

g

150

1050

0+

050

00A

MJ

JA

SO

ND

JF

M

Hay 50

Hay

100

150

100

5050

2R

ange

LSH

, SI 3

520

0.6

120

+0

120

1218

2424

1212

126

CB, S

I 30

100

1.212

0-

012

012

1824

2412

1212

6

Stee

p Ro

cky,

SI

7020

0.3

60

+.9

546

811

115

55

3

Tota

l for

rang

e50

0-

--

-29

430

4459

5929

2929

15

Tota

l55

079

430

9415

920

912

979

7915

00

00

Feed

Hay

: Ha

rves

t hay

from

Fiel

d 1 M

ay, J

une

83

TON

S =

210

AUM

*

Pro

tein

: Pur

chas

e 2 lb

/AU/

Dec.,

Jan

., Feb

. 6

TON

SX

XX

J.R.

Sto

ckto

nR.

C. J

ones

4|9

|96

*

Hay

Pro

duct

ion

Cal

cula

tions

for P

astu

re 1

:15

0 A

U x

790

.8 lb

= 1

18,6

20 lb

har

vest

ed b

y gr

azin

g11

8,62

0 / .

50 =

237

,240

lb p

rodu

ced

on p

astu

re (.

50 =

50%

har

vest

effi

cien

cy)

237,

240

x .7

0 =

166,

068

lb h

arve

sted

as

hay

(.70

= 70

% h

arve

st e

ffici

ency

for h

ay)

166,

068

/ 2,0

00 =

83

tons

hay

166,

068

/ 790

.8 =

210

AU

M h

ay

Chapter 5



Ex

hib

it 5

–3

Wor

kshe

et—

Stoc

king

Rat

e an

d F

orag

e V

alue

Rat

ing

Sto

ckin

g R

ate

An

d F

ora

ge

Val

ue

Rat

ing

Eco

log

ical

Sit

e: O

per

ato

r:

Pas

ture

No

: L

oca

tio

n:

A

cres

: C

on

serv

atio

nis

t: D

ate:

Can

op

y:

Pot

entia

l con

sum

ed (l

b/ac

x H

E)

Act

ual c

onsu

med

No

tes

:

Pre

sent

com

posi

tion

Ani

mal

:A

nim

al:

Ani

mal

:A

nim

al:

Pla

nt s

peci

esW

eigh

t lb/

ac%

PD

UD

PD

UD

PD

UD

PD

UD

Tot

al

Tot

al fo

rage

con

sum

ed (S

um o

f P, D

, UD

):

Pou

nds

per A

UM

:

AU

M/a

c (fo

rage

con

sum

ed /

790.

8):

Ac/

AU

(12

/ A

UM

/Ac)

:

% b

y P

refe

renc

e:///

//////

//////

//////

//////

/////

//////

//////

//////

//////

///

For

age

valu

e ra

ting:

//////

//////

//////

//////

/////

//////

//////

//////

//////

//////

Har

vest

effi

cien

cy fa

ctor

s: P

= .3

5, D

= .2

5, U

D =

.15



Exhibit 5–3 Worksheet—Stocking and Forage Value Rating—Continued

Instructions for Stocking Rate Based onPreference and Forage Value Rating

This is a method to determine stocking rate based on consumption of forage allocated by preference of animal species. When wildlifeare on the site, allocate feed to them first. Livestock stocking rate is based on the remaining forage. If more than one wildlife speciesare present, allocate to the larger animal first, then to the next smaller wildlife species. The remaining forage is then allocated tolivestock. If more than one type of livestock are on the site, allocate feed to the larger animal first, then the smaller. This ensures thearea will not be overstocked with a combination of wildlife and livestock.

1. Record the name of the site being inventoried.2. Record the management unit number.3. Record the acreage of the area represented by the plant community being evaluated.4. Record the date of the inventory.5. Record the name of the client.6. Record the field office name.7. Record the name or initials of the person providing the technical assistance.8. Record the canopy of the overstory of woody species.9. Determine the present plant community composition by weight, then calculate the percentage composition. The

composition is based on the forage within reach of the animal, normally below 4 1/2 feet.10. Compute the potential pounds consumed by multiplying the harvest efficiency times the pounds per acre of each plant listed

in the community. Use the following harvest efficiencies: Preferred = 35%, Desirable = 25%, and Undesirable =15%. Place the pounds consumed under the proper preference heading.

11. Total the pounds harvested for each preference heading. Then, sum the production for total forage consumed.12. Compute the AUM/AC by dividing the total forage consumed by 790. (The pounds allocated to an AUM).13. Determine the AC/AU by dividing 12 by the AUM/AC.14. Compute the forage value rating by determining the percent preferred, desirable and undesirable for the animal. Compare

the percent preferred and desirable to the following Table to determine the forage value rating.

Very high 50% P + D = 90%High 30% P + D = 60%Moderate 10% P + D = 30%Low Less than 10 P

15. Compute AUM/AC and AC/AU and the forage value ratingfor the other animals following the above guidance. (Steps 10through 14.)

16. Compute the pounds per acre consumed by the different wildlife species presently on the site.

Example:If site has one deer per 15 acres, divide 9490 pounds (Amount of forage allocated to an Animal Unit Year) by 15 = 632.6pounds per acre total forage consumed by one AU of deer. Five Deer = one AU in this case. Divide 632.6 by 5 deer = 126.5pounds of forage per acre consumed by deer.

or

9490 divided by 5 deer = 1898 pounds of forage consumed by one deer. 1898 divided by 15 acres = 126.5 pounds peracre of forage consumed by deer when there is one deer per 15 acres.

17. Compute the forage consumed by wildlife (deer) by first recording the pounds consumed per acre (126.5) in the total forageconsumed line and in the deer portion of actual consumed. Then, allocate preferred, desirable, and undesirable forages inthat order until the deer are fed the computed forage consumed (126.5 pounds in example). When a forage plant is used tothe maximum harvest efficiency level, then none is available to livestock or the next smaller wildlife species. If forage isleft, then the remaining amount is allocated to the next smaller wildlife or livestock. Allocate the remaining plants to thelivestock or next smaller wildlife in the same manner.

18. Then, compute the livestock and wildlife AUM/AC and AC/AU based on the new total forage consumed for the livestock andwildlife. (Example: 48 AC/AU compared to the 35.3 AC/AU for livestock originally computed.) If wildlife populations aregreater than what the “potential” computation show is advisable, then the plants will be overused, and there will be none ofthe wildlife plants available for the livestock.

Note: The Multi-Species Calculator in Grazing Land Applications (GLA) will accomplish all these calculations. Average harvestefficiency will also be calculated for the plant community selected.

Chapter 5



Ex

hib

it 5

–3

Wor

kshe

et—

Stoc

king

Rat

e an

d F

orag

e V

alue

Rat

ing—

Con

tinu

ed

Exa

mp

le –

Sto

ckin

g R

ate

An

d F

ora

ge

Val

ue

Rat

ing

(1) E

colo

gic

al S

ite:

(5) O

per

ato

r:

(2) P

astu

re N

o:

(6) L

oca

tio

n:

(3

) Acr

es:

(7) C

on

serv

atio

nis

t:(4

) Dat

e:(8

) Can

op

y:

(1

0)

(1

7)

(9

)P

oten

tial c

onsu

med

(lb/

ac x

HE

)A

ctua

l con

sum

edN

ote

s:

(16

)

(9)

Pre

sent

com

posi

tion

Ani

mal

:A

nim

al:

Ani

mal

:A

nim

al:

Pla

nt s

peci

esW

eigh

t lb/

ac%

PD

UD

PD

UD

PD

UD

PD

UD

Tot

al(1

1)

(11

)(1

1)

(11

)(1

1)

(11

)

Tot

al fo

rage

con

sum

ed (S

um o

f P, D

, UD

):(1

1)

(11

)(1

8)

(18

)

Pou

nds

per A

UM

:

AU

M/a

c (fo

rage

con

sum

ed /

790.

8):

(12

)(1

5)

(18

)(1

8)

Ac/

AU

(12

/ A

UM

/Ac)

:(1

3)

(15

)(1

8)

(18

)

% b

y P

refe

renc

e:(1

4)

(14

)(1

4)

//////

//////

//////

//////

/////

//////

//////

//////

//////

//////

For

age

valu

e ra

ting:

(14

)(1

5)

//////

//////

//////

//////

/////

//////

//////

//////

//////

//////

Har

vest

effi

cien

cy fa

ctor

s: P

= .3

5, D

= .2

5, U

D =

.15

San

dy L

oam

I. B.

Goo

d

12

Hap

py H

ollo

w

100

RHJ

4/

10/9

6

45

%

Pot

entia

l Site

has

1 D

eer /

15

Ac.

Pin

e H

ill B

lues

tem

500

5017

5

Catt

leDe

erDe

erCa

ttle

175

9,49

0 lb

/ 15

= 6

32.6

lb/A

c.

Low

Pan

ic50

512

.512

.51.5

11

632.

6 / 5

= 1

26.5

lb. C

onsu

med

by

Sw

eet G

um10

010

1525

25

deer

per

acr

e, o

r

Am

er. B

eaut

y B

erry

100

1025

3535

9,49

0 / 5

dee

r = 1

,898

lb/d

eer.

Car

petg

rass

505

12.5

12.5

1,89

8 / 1

5 A

c =

126.

5 lb

/Ac

St.

And

rew

s C

ross

505

7.512

.512

.5

cons

umed

by

deer

.

Sas

safra

s15

015

22.5

52.5

52.5

1000

100

175

5045

87.5

500

87.5

3917

523

.5

E

stim

ated

S

tock

ing

Rat

e :

270

lb/ac

137.5

lb/a

c

126.

5

198.

5

Dee

r : 1

dee

r to

15 A

c =

6.6

deer

790.

879

0.8

790.

879

0.8

Cat

tle :

100

x .2

5 =

25A

UM

, or

.34

AUM

/Ac

.17

AUM

/Ac

.16.25

2

AU

yea

r lon

g

35.

3 Ac

/AU

70.

6 Ac

/AU

7

5 Ac

/AU

4

8 Ac

/AU

5020

3025

200

Hig

h

Mod

erat

e

Chapter 5


Management of Grazing Lands National Range and Pasture HandbookExhibit 5–4 Worksheet—Determining Forage Composition and Value Rating

Worksheet for Determining Forage Compositon and Value Rating

Ecological Site: Operator: Location:

Pasture Number: Conservationist: Date: Canopy:

Presentcompostion Animal: Animal: Animal:

Plantspecies Weight %

Foragevalue P D

Foragevalue P D

Foragevalue P D

TOTAL

Forage value rating 1 /

Planned trend 2/

Total estimated yield in very high forage value rating for cattle: 1/ Forage value rating for cattle and wildlife:

(P = preference: D = desirable) Very high 50% P + D = 90%High 30% P + D = 60%

2/ Planned trend symbols: Improving + Moderate 10% P + D = 30%Low Less than 10% PNon-detectable ❏

Moving Away – * Key grazing plant Estimated initial stocking rate: Notes:



Exhibit 5–4 Worksheet—Determining Forage Composition and Value Rating—Continued

Instructions for Worksheet For DeterminingForage Composition And Value Rating

1. Record the name of the site that you are inventorying.2. Record the management unit number.3. Record the date of the inventory.4. Record the name of the client.5. Record the field office name.6. Record the name or initials of the person providing the technical assistance.7. Record the canopy of the overstory of woody species.8. Record the plant species inventoried on the site.9. Record the weight of each species in pounds per acre.

10. Record the percentage composition for each species.11. Record the animal for which you are computing the forage value rating.12. For each plant species list the forage value (preferred or desirable) for the animal of concern.13. For the plant species rated as preferred, list the percentage composition found in the present

composition. (See item 10.)14. For the plant species rated as desirable, list the percentage composition found in the present

composition. (See item 10.)15. Record the total weight in pounds per acre of the plants inventoried.16. Record 100 %.17. Record the total percentage of the preferred plants.18. Record the total percentage of the desirable plants.19. Record the forage value rating for each animal as calculated using the chart provided.20. Record the direction of plant community movement in relation to the desired plant community

for each of the animals of concern. Is the forage value rating improving, not detectable, ormoving away from the desired plant community for the animal of concern?

21. Record the total estimated yield for a very high value rating for livestock as a point ofreference. This data should be recorded in the ecological site description for rangeland orforest land.

22. Identify the key grazing plant for each animal of concern.23. Record the estimated safe starting stocking rate for the site. This may be taken from the

ecological site description or calculated based on the production of preferred and desirablespecies.

Example: Cattle

500 pounds preferred times 35% harvest efficiency = 175 pounds200 pounds desirable times 25% harvest efficiency = 50 pounds

Total harvested = 225 pounds9,490 (pounds in AUY) divided by 225 pounds = 42 acres required per animal unit of cattle.

24. Record notes needed to ensure understanding of inventory.

Chapter 5


Management of Grazing Lands National Range and Pasture HandbookExhibit 5–4 Worksheet—Determining Forage Composition and Value Rating—Continued

Example – Worksheet for Determining Forage Compositon and Value Rating

(1) Ecological Site: (4) Operator: (5) Location:

(2) Pasture Number: (6) Conservationist: (3) Date: (7) Canopy

(8) Presentcompostion Animal: (11) Cattle Animal: (11) Deer Animal: (11) Turkey

Plantspecies

(9)

Weight(10)

%Foragevalue (12)

(13)

P(14)

DForagevalue(12)

(13)

P(14)

DForage

value (12)

(13)

P(14)

D

TOTAL (15) (16) (17) (18) (17) (18) (17) (18)

Forage value rating 1 / (19) (19) (19)

Planned trend 2/ (20) (20) (20)

(21) Total estimated yield in very high forage value rating for cattle: 1404 lb/Ac1/ Forage value rating for cattle and wildlife:

(P = preference: D = desirable) Very high 50% P + D = 90%High 30% P + D = 60%

2/ Planned trend symbols: Improving + Moderate 10% P + D = 30%Low Less than 10% PNon-detectable ❏

Moving Away –(22) * Key grazing plant(23) Estimated initial stocking rate: 1 AU to 42 Ac(24) Notes:

High Moderate High

+ + +

Sandy Loam Pat StocktonHappy Hollow

12 RHJ4/10/96 45%

Pinehill Bluestem 500 50 P * 50 UD P * 50

Low Panic 50 5 D 5 D 5 D 5

Sweet Gum 100 10 UD D 10 UD

American Beauty Berry 100 10 D 10 P 10 D 10

Carpet Grass 50 5 D 5 UD D 5

St. Andrews Cross 50 5 UD D 5 D 5

Sassafras 150 15 UD P * 15 UD

1000 100 50 20 25 20 50 25

Chapter 5



Ex

hib

it 5

–5

Wor

kshe

et—

Live

stoc

k In

vent

ory

and

For

age

Bal

ance

Liv

esto

ck In

ven

tory

an

d F

ora

ge

Bal

ance

Wo

rksh

eet

Co

op

erat

or:

Dat

e:

Tec

hn

icia

n:

Liv

esto

ck N

um

ber

s an

d F

ora

ge

Nee

ds

An

imal

un

its o

f fo

rag

e n

eed

ed

Mo

nth

s

Live

stoc

kn

um

ber

equi

v.u

nit

sA

UM

's

To

tal

To

tal f

orag

e av

aila

ble

(AU

M's

)

Pla

nned

AU

An

imal

T

otal

fora

ge n

eeds

(AU

M's

)

D

iffer

ence

(+

) or

(-)

(A

UM

's)

2/

1/

1/ T

ake

this

dat

a fro

m fo

rage

inve

ntor

y.2

/ S

ubtra

ct to

tal f

orag

e ne

eds

from

tota

l for

age

avai

labl

e.

NO

TES

:



Exhibit 5–5 Worksheet—Livestock Inventory and Forage Balance—Continued

1. Enter client’s name.2. Enter date of technical assistance.3. Enter name of person providing technical assistance.4. Record the identification of a specific herd, flock, etc. of animals being

inventoried. This generally includes information, such as the kind, breed,class, and age. Record each different group of animals. Maintain separategroups needed for desired husbandry to be practiced.

5. Record the number of animals in the group identified on the line.6. Record the animal unit equivalents for the identified group.7. Multiply the planned number of animals (item 5) times the AU equivalents

(item 6), and record the product. This number represents the animal units ofthe particular number of animals recorded on this line.

8. Record the months in the same manner as you did in the forage inventory.This should start with the month that best reflects the growing and grazingseason for the year. Record the animal unit equivalents in the months theanimals will be on the operating unit during the year.

9. Enter the total of the animal unit months recorded for each line.10. Continue to list the animals as in item 4 above.11. On this line, list the AUMs in each month. This information comes from the

forage inventory that has been developed for the operating unit.12. Total the animal units column, and the AUMs for each month, and the total

AUMs column, indicating the total AUMs of forage needed.13. Subtract the total forage needs line from the total forage available line and

record the AUM differences, indicating whether there is a shortage (-) orexcess (+) of forage available that month, and for year.

14. Record notes needed to explain any part of the worksheet.

Chapter 5



Ex

hib

it 5

–5

Wor

kshe

et—

Live

stoc

k In

vent

ory

and

For

age

Bal

ance

—C

onti

nued

Exa

mp

le –

Liv

esto

ck In

ven

tory

an

d F

ora

ge

Bal

ance

Wo

rksh

eet

Co

op

erat

or:

D

ate:

Tec

hn

icia

n:

Liv

esto

ck N

um

ber

s an

d F

ora

ge

Nee

ds

An

imal

un

its o

f fo

rag

e n

eed

ed

Mo

nth

s

Live

stoc

kn

um

ber

equi

v.u

nit

sA

MJ

JA

SO

ND

JF

MA

UM

's

To

tal

To

tal f

orag

e av

aila

ble

(AU

M's

)

Pla

nned

AU

An

imal

1/

T

otal

fora

ge n

eeds

(AU

M's

)

D

iffer

ence

(+)

or

(-)

(AU

M's

)

2/

1/ T

ake

this

dat

a fro

m fo

rage

inve

ntor

y.2/

Sub

tract

tota

l for

age

need

s fro

m to

tal f

orag

e av

aila

ble.

NO

TES

:

Cons

erva

tion

ist

4/10

/96

Nam

e

66

3094

159

209

129

7979

150

00

0

64

64

64

64

64

64

64

64

64

64

64

64

64

+2-3

4+3

0+9

5+1

65+6

5+1

5+1

5-4

9-6

4-6

4-6

4-6

4

794

768

+26

60

x 1

= 6

06

06

06

06

06

06

06

06

06

06

06

06

0

3x 1

.25

=4

44

44

44

44

44

44

720

48

x

=

x

=

x

=

Cow

s

Bul

ls

(4)

(10

)

(11

)

(12

)

(13

)

(14

)

(3)

(2)

(1)

(5)

(6)

(7)

(8)

(9

)

Chapter 5



Ex

hib

it 5

–6

Wor

kshe

et—

Pre

scri

bed

Gra

zing

Sch

edul

e

P

resc

rib

ed G

razi

ng

Sch

edu

le

Coo

pera

tor:

Typ

e of

ent

erpr

ise:

(c

ow-c

alf,

sto

ck,

or c

ombi

natio

n, s

tock

& w

ildlif

e):

Tec

hnic

ian:

A

nim

al u

nits

on

hand

:

Pla

nned

ani

mal

units

:

Dat

e:

Kin

d an

d es

timat

ed n

umbe

r of

wild

life:

Gra

zin

g u

nits

an

dT

ota

l AU

M's

Rec

ord

by

mo

nth

the

pla

nn

ed n

um

ber

of a

nim

als

in e

ach

gra

zin

g u

nit

To

tal A

UM

'ssc

hed

ule

dki

nd

s o

f fo

rag

eA

cres

avai

labl

e

TO

TAL

Not

es:



Exhibit 5–6 Worksheet—Prescribed Grazing Schedule—Continued

Instructions for Prescribed Grazing Schedule

1. Enter client’s name.2. Enter name of person providing technical assistance.3. Enter date of technical assistance.4. Enter type of livestock or wildlife enterprise.5. Enter number of animal units of animals presently on land.6. Enter number of animal units of animals for which the plan is being

developed.7. Record the kind and estimated number of grazing and browsing wildlife on

the operating unit.8. Record the number of the pasture or field and the pertinent information that

affects the production, such as forage suitability group, fertilization rate,harvest efficiency.

9. Record the acreage in the pasture or field.10. Record the total AUMs available in the field or pasture for the year.11. Enter the months in a manner that matches the months listing on the forage

inventory, or in a manner that best depicts the grazing period in relation togrowth of forage.

12. Record by month the AUMs of animals scheduled to graze in each of thepastures or fields during the year. Also record mechanical forage harvest orthe allocation of forage used in any other manner.

13. Record the total of AUMs scheduled in the pasture or field.14. Record the total for all columns.15. Record notes needed to explain any part of the worksheet or information

needed for followup evaluations. Notes should include information aboutsupplemental feeding, plans of action in case of drought, future adjustments,desired trends, sales or shipping dates, hunting seasons, husbandry dates(dates of breeding seasons), calving or lambing season, livestock workingdates, type of grazing system, fertilizer rates and dates, and otherinformation pertinent to the operation of the grazing schedule.

Chapter 5



Ex

hib

it 5

–6

Wor

kshe

et—

Pre

scri

bed

Gra

zing

Sch

edul

e—C

onti

nued

Exa

mp

le –

Pre

scri

bed

Gra

zin

g S

ched

ule

Coo

pera

tor:

(1

)

Typ

e of

ent

erpr

ise:

(c

ow-c

alf,

sto

ck,

or c

ombi

natio

n, s

tock

& w

ildlif

e):

Tec

hnic

ian:

(2

)

(2)

Ani

mal

uni

ts o

n ha

nd:

(5)

Pla

nned

ani

mal

uni

ts:

Dat

e:

(3) (1

5)

(14)

Kin

d an

d es

timat

ed n

umbe

r of

wild

life:

(7)

Sup

plem

enta

l Fee

dD

roug

ht P

lans

(Whe

n &

How

)1.

Pro

tein

sup

plem

ent w

ill b

e fe

d as

nee

ded

in D

ec.,

Jan.

, and

Feb

.

Fut

ure

Adj

ustm

ents

Tre

nds

2. I

nven

tory

of F

orag

e P

rodu

ctio

n w

ill b

e ta

ken

Aug

ust 1

st.

Sto

ckin

g w

ill b

e ad

just

ed b

ased

on

o

n cu

rren

t for

age

inve

ntor

y an

d pr

ojec

ted

prod

uctio

n. A

t fro

st, a

n in

vent

ory

of fo

rage

will

be

mad

e

and

sto

ck n

umbe

rs b

alan

ced

with

fora

ge a

vaila

ble

to c

arry

ani

mal

s th

roug

h M

ay.

Sal

es o

r Shi

ppin

g D

ates

Hus

band

ryT

ype

of G

razi

ng S

yste

mF

ertil

izer

Rat

es a

nd D

ates

Oth

er In

form

atio

n

(6)

(4)

Gra

zin

g u

nits

an

dT

ota

l AU

M's

Rec

ord

by

mo

nth

the

pla

nn

ed n

um

ber

of a

nim

als

in e

ach

gra

zin

g u

nit

To

tal A

UM

'ssc

hed

ule

dki

nd

s o

f fo

rag

eA

cres

avai

labl

e

TO

TAL

Not

es:

50#1

Ber

mud

a 3A

Hig

h, 5

0H

.E. (

500

AUM

's)

#2 R

ange

land

(294

) AUM

's)

Hay

feed

on

Rang

elan

d(1

55 A

UM's

)

Hay

Har

vest

from

#1

(208

AUM

's)

64

64

64

64

64

500

33

AM

JJ

AS

ON

DJ

FM

336

46

433

3333

3131

3131

31 (50)

(36

)(8

6)

(36

)

550

64

64

64

64

64

64

64

64

64

64

64

64

64

64

Cow/

calf

Non

e

Ranc

her

Cons

erva

tion

ist

4/10

/96

(8)

(9)

(11)

(10)

(12)

(13)

chapter 5 management of grazing lands - usdachapter 5 management of grazing lands national range and...

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