Pasture Ecosystem

Farming Systems Native Ecosystem

Grazing and Invasives

Sue Ellen Johnson PhD. Director of Agriculture and Rural Economy Piedmont Environmental Council

Pastures are communities of individual plants Usually mixtures of herbaceous perennials and annuals

Pasture plant communities Seasonally dynamic (warm and cool season) Competitive

Aboveground: compete for light, space Below-ground: compete for water, nutrients, soil

Plant community affected by: Livestock grazing, treading, manure and urine Human mowing, chemical application…

Goals for pasture: Fresh green (affordable) quality feed for livestock/horses Green space for animals to derive some nutrition and exercise Beautiful “pastoral” “bucolic” landscape Economic contribution to Piedmont farming systems

GRAZING GOALS ???

Productivity per acre fenced?Productivity per unit of fertilizer?Productivity per unit labor?

Gain per animal?Gain per acre?

Profit per acre? Profit per year ? Profit per hour of labor?

Hobby and recreation?Tax status? Pretty pasture?

In pastures: Desirable and Undesirable Plants

Desirable : Palatable, non-toxic, nutritious, high yielding, competitive plants that can tolerate trampling and repeated defoliation (and regrow) Ideally persistent, resilient, easy to establish

Naturalized non-natives Natives Exotics

Undesirable: compete with desirables Limit animal performance and land productivity

or adversely affect the environment Native and non-native weeds

some of which are invasive

Pastures not the “native” Piedmont landscape Mostly naturalized European plant species maintained through human action (?)

Warm and cool season plant species

Most pastures have diverse mixtures of plant speciesPersistent perennials and naturally reseeding annuals

Warm season GrassesBermudagrassNWSG

LegumesLespedeza

GrassesCrabgrass*Sorghum and Millet

LegumesLespedeza

Perennials

Annuals

Piedmont Forages

Cool season GrassesTall fescue OrchardgrassKentucky bluegrassPerennial RyegrassLegumesAlfalfa White and Red clover(s)

GrassesAnnual ryegrass*BromegrassesSmall grains: Oats, wheat, triticale, rye

LegumesCrimson clover

* = naturally reseeding annual

Fescue

Orchardgrass

Bluegrass

Soil level

Crabgrass

Basic good grazing management helps desirable plants thrive and minimizes undesirable weeds and invasivesin Northern Piedmont pastures while increasing productivity and profitability of a pasture enterprise

Desirable plants must thrive and compete, not simply survive: Keep good, desired plants species competitive…Maintain canopy between 4-8” to

keep light from reaching the ground keep soil covered to manage soil temperature and moisture

Maintain canopy between 4-8” by Rotating livestock to new pastures – every 3 days

once a plant is grazed allow it time to regrow Do not overstock or overgraze

Managing grazing to manage weeds and invasives

For a competitive canopy: need 4x the leaf surface area relative to soil surface area

For each square foot of soil surface: 4 square feet of leaf surface area

In pastures, leaves (not stems) should make up most of the canopy most of the time.

Set mowers at 4” (minimum)

Maintain canopy between 4 and 8”

Time mowing to rainfall

Mow when desirable plants will rapidly regrow (before budding)

Dragging?

Equipment and tires transport weed seeds

Have a “sacrifice” pasture (or drylot) during high stress periodsStress= drought or wet

IF mowing pastures

Invasives (seed or vegetation) 1. Land in favorable site2. Germinate or root3. Outcompete other plants in that site4. Reproduce

Blaser VPI 1986

Grazing (mowing) heights affect pasture species composition

“Pioneer” species. Invades open, disturbed spaces.Limit by maintaining dense 4” minimum pastures.

Spotted knapweed Centaurea maculosa

j. riley stewart photo

VT

Buttercup Ranunculus spp

Native and exotic spp. R. pennsylvanicus is threatened All are weeds in pasture: unpalatable, toxic

Colonizes open, disturbed sitesLikes wet, compacted soils, low pH

Avoid grazing wet areas-hoof nichesLimit by maintaining dense 4” pasturesShades out if shaded early in the season…

Pasture micro-sitesPlants (forages or weeds) fit into the micro-sitesabove and below ground.Depends on what seed is there.

Do NOT control a pasture weed without seeding something desirable in its place. Time control to favor the desirable species as well as to eradicate the problem.

AVOID creating microsites - opportunities for invasives to invade Avoid “overgrazing”

Do NOT graze below 3-4 inches Use pasture rotation or exclosure

Pasture Weeds and Forage Diversity

Forage Diversity (# of forage types in the pasture)*Averaged over two years

2 SP 3 SP 6 SP 9 SP02468

10121416

% w

eeds

Soder et al. 2005

What makes a plant a pasture weed/undesirable?• Poor palatability • Poor yield • Propensity to spread- crowds out other species• Toxicity

Think carefully before eliminating anything that is grazed.Any plant that is grazed (palatable) and is not toxicand is not spreading is tolerable in an average pasture.

Use plant competition to (shading and crowding, allelopathy) limit undesirable plants. Overseed an annual forage: sorghum, millet, rye, annual ryegrass to reduce the vigor of some undesirables

Scout [Know desirables from undesirables] Control weeds at early growth stages- before they “take over”Spray, burn, dig, mow, overseed, shade, graze…Use spot control when possible.

Change soil (root) conditions: temperature and moisture

fertility: nitrogen pH

Controlling undesirables/invasives in pasture

Time and manage fertilization, seeding, grazing and mowing to favor desirables.

Make sure a desirable species will “replace” what you are controlling (load the seedbank).

MUST change grazing/pasture management that resulted in weed invasion in the first place to prevent recurrence!

WI

Controlling undesirables/invasives in pasture

Desirable vs undesirable pasture species

What plants are we talking about?

Nimblewill Mulhenbergia schreberi

YES NO MebbeNative?Invasive?Good pasture?

Stiltgrass: Microstegium vimineum

YES NO MebbeNative?Invasive?Good pasture?

Eastern gamagrass Tripsacum dactyloides

YES NO MebbeNative?Invasive?Good pasture?

Eastern gamagrass

Switchgrass

NWSG Pastures- designated for warm seasonNOT grazed during winter monthsrotationally grazing May-September Attentive management: 4-6” residualBig bluestem, Indiangrass, Eastern Gamagrass, Switchgrass,Buffalo grass

Johnsongrass Sorghum halepense

YES NO MebbeNative?Invasive?Good pasture?Locally invasive?

To eliminate palatable species: continuously grazeAllow unrestricted access.

Crabgrass

YES NO MebbeNative?Invasive?Good pasture?

Digitaria sanguinalis

Stickweed or Wingstem or Yellow Crownbeard: Verbesina occidentalis

YES NO MebbeNative?Invasive?Good pasture?Locally invasive?

YES NO MebbeNative?Invasive?Good pasture?

Foxtail (Setaria spp. )

Kentucky BluegrassPoa pratensis

Goosegrass Eleusine indica

Broomsedge Andropogon virginicus

Weeds = management problems

Undesirable: low yielding, marginal palatability;indicates compaction

Undesirable: unpalatable; indicates low pH

Lespedeza cuneata“Sericea”

http://www.cottoncrc.org.au/files/ed326f7a-15f4-4f74-9c8f-994401342942/Burr%20medic.jpg

Hop clover Trifolium campestre

YES NO MebbeNative?Invasive?Good pasture?

Burr clover

RyegrassLolium perenneLolium multiflorum

J. Koivisto

Crown vetch Coronilla varia

Hairy vetch Vicia villosa

YES NO MebbeNative?Invasive?Good pasture?

Tall fescue Festuca arudinacea

YES NO MebbeNative?Invasive?Good pasture?

Grazing as a means to control invasives

Mixed species grazing and invasives

7:30 am

Pigweed stems stripped bare of leaves after 20 hours high density goat stocking

Diverse pasture mixtures more competitive with weeds

Henbit (Lamium amplexicaule)

X

www.anr.ext.vt.edu/lawnandgarden/turfandgardentips/pdfs/nimblewill_bermuda_id.pdf

http://www.caf.wvu.edu/~forage/tutorial/

www.fcps.edu/islandcreekes/ecology/

www.extension.umn.edu/forages/pdfs/Native_Legumes.pdf

http://www.gardenorganic.org.uk/organicweeds/weed_management/show_wman.php?id=10 pigs

Extras

Pastures that are also hayed: Invasives may be more challenging.. because

Hay Market is Less tolerant of species diversity-mixed hays More opportunities for invasives…

How desirtbale plants disapper form pasturesHow undeairtbale palnts apread in pstures Baic graing management

Warm season and cool season plants.. Two plant canopy populations…

What not to plant because of it’s invasive potential…Careful with hay :

Seeds it may introduceHay feeding sites create invasion sites

Pasture invasives: are they spreading?Are they an economic (or health )liability ) visual or ecological problem?

If ypu finmd one invasive: :FlameHerbicides etc

In an established forage field

Light: energy for photosynthesis

PlantsLeaves: site of photosynthesisStems: support and position the leaves to capture sunlight Roots: anchor the plant, move water and nutrients into the plant

Water: carries the nutrients to the plant roots and into the plants forage plant at max growth rate is 90% water (10% DM)

Soil: physically support the plant and hold nutrients and water

Nutrients: combined with carbon from photosynthesis to build plant tissues, move into the plant with water

Managing Grass-Legume Mixtures

WI

A 30-50% stand is a good legume stand.

WI

20% stand

70% stand

3”

Pre-graze Post-graze

Regrowth from stolon

Regrowth from leaf blade

In addition to photosynthesis, canopy is important formanaging soil cover and consequently soil temperature and soil water which effect which species grow in the pasture.

Time or age

Slowgrowth

Rapidgrowth

Rela

tive

Gr o

wt h

Rat

e

Growth Stages and Growth Rates

New shootsor seedlings Vegetative Reproductive

Slowergrowth

Different livestock species Different grazing objectives…

Minimum heifht

Minimum leaf area…..

Grazing and invasives How to think about pasture plants and weeds

Ecological Niche

OpportunitiesDisplacementReplacementSEEDBANK

Nimblewill, stiltgrass, goosegrassFescue orchard grass alfalfa red clover white clover ryegrassSericea

Tolerable Purpletop.. Johnsongrass

Undesirabkels…Mint (s)Buttercup, burrs, Burr clover, hop cloverthistles

Natives that are problematic in pastures Yellow crownbeard - wing-stem…Do ck(s)

Natives for pasturesNWSG summer grazing Invasives as pasture indicators

problems beyond the pasturePastures as invasive reservoir

Clovers Mints Stickweed

Undesirable natives? Tolerable?

SericeaLespedeza’s

Vetches

Species useful; or tolerable in a “native friendly” pasture…

Grazing and invasives How to think about pasture and pasture plants What are undesirable or invasive pasture species (weeds) How to manage grazing to prevent/avoid undesirable or invasive pasture species How to control undesirable or invasive plants in pastures with grazing

WI

Prevention of invasives: What grazing systems result/favor invasives?

Control and eradication of invasives

Don’t plant invasive problems; don’t create niches