pasture fertility and management - university of...
TRANSCRIPT
1
Pasture Fertility and
Management
Sarah Kenyon
Agronomy Specialist
(417) 967-4545
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What is Soil?
• The unconsolidated mineral or organic
material on the immediate surface of the
earth that serves as a natural medium for
the growth of land plants.
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Soil Biodiversity and Habitat
• Complex, ‘living’ system
– 10,000 different species in 1-g of soil
– 1.5 times as many individual organisms in a
teaspoon of soil as people on earth (Doran et al., 1996)
• Vulnerable resource
– 100-400 years to create 1-cm of topsoil (Jenny, 1980)
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• Mineral matter of a soil determines its texture.
• Texture is based on the amounts of sand, silt, and clay in the
soil.
Soil Texture
Sand:
2.0 to 0.05 mm
Silt:
0.05 to 0.002 mm
Clay:
< 0.002 mm
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Properties of Soils
Physical Properties
• Texture
• Structure
• Porosity
• Water content
• Strength
• Temperature
• Color
• Bulk Density
• Rooting Depth
• Infiltration rate
• Water Holding Capacity
• Aggregate Stability
• Web Soil Survey
• http://websoilsurvey.nrcs.usda.gov/ap
p/HomePage.htm
• Missouri CARES
• Center for Applied Research and
Environmental Systems
• http://www.cares.missouri.edu/
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Properties of Soils
Chemical Properties
• Soil chemical properties are
determined by the amounts
and types of soil colloids
(clays and organic matter).
• Chemical properties include
– Mineral solubility & Nutrient
availability
– Electrical Conductivity (EC)
– Soil reaction (pH)
– Cation exchange capacity
– Buffering action
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9 Macronutrient elements:
C H O N K P Ca Mg S
8 Micronutrient elements:
Mn Zn Cu Cl B Fe Mo Ni
Some other elements that are beneficial:
Na Si V Co Al
Mineral Nutrition
Why test your soil?
• Avoid potential nutrient deficiencies
• Identify possible causes for poor pasture or
hay production
• Save money $$$
– Apply enough plant nutrients
– Avoid excessive expense
Sampling Tools
• Shovel or spade
• Soil probe
• Soil auger
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Get a Useful Sample
• 15 – 20 Cores
• 6 Inches Deep
• Place in a clean bucket
and mix well
• Remove grass, sticks,
and rocks
• Place about a pint of
soil in a soil sample
box & label
• Discard excess soil
Timing of Soil Sampling
• Avoid sampling soon after fertilization, liming, or manure application.
• Best to wait 3 months
• Sample every 2 to 3 years. • Better to do a quality job (more cores per sample) less
frequently
• Sample the same time every year.
• Avoid sampling within 150 feet of watering points, shade trees, gravel roads and other known hot spots
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Soil test data from one core is highly variable
0
20
40
60
80
100
120
140
160
180
200
1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61
Core number
Soil
tes
t P
(B
ray-I
, lb
s./a
cre)
Mean: 44 STD: 48
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Accuracy can be increased by dividing fields based
on known variability
0
20
40
60
80
100
120
140
160
180
200
4 9 13 19 23 27 31 37 43 48 52 56 60 1 17 38
Core number
Soil
tes
t P
(B
ray-I
, lb
s./a
cre)
Feeding areas Old manure piles
Overall Mean: 44, STD: 48
Pasture mean: 20, STD: 17
Feeding area mean: 114, STD: 52
Pasture
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Get a Useful Sample
• Sample 20 acres
or less
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1 sample/ 60 acres
N P2O5 K2O
60 acres 50 50 50
3000 lbs of each
$2490 $1590 $1560
$5,640 total
Price ($)/lb of nutrient: MFA, Cabool 7/24/2012
N $0.83 - P2O5 $0.53 – K2O $0.52
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2 samples/ 60 acres
N P2O5 K2O
20 acres 50 50 50
lbs of each 1000
$830 $530 $520
40 acres 50 50 20
lbs of each 2000 2000 800
$1660 $1060 $416
$5,016 total
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3 samples/ 60 acres
N P2O5 K2O
20 acres 50 50 50
lbs of each 1000
$830 $530 $520
20 acres 50 50 20
lbs of each 1000 1000 400
$830 $530 $208
20 acres 50 0 20
lbs of each 1000 0 400
$830 $0 $208
$4,486 total
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Same 60 acres
• 1 sample = $5,640
• 2 samples = $5,016 - $624 savings
• 3 samples = $4,486 - $1,154 (1) $530 (2)
Avoiding unneeded application of 5 lbs P2O5/acre
on 20 acres would pay for
4 soil tests
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Get a Useful Sample
• Sample 20 acres
or less
• 15 – 20 Cores
• 6 Inches Deep
• Place in a clean bucket
and mix well
• Remove grass, sticks,
and rocks
• Place about a pint of
soil in a soil sample
box & label
• Discard excess soil
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A. Field info
B. Soil test info
C. Rating
D. Nutrient
requirements
E. Cropping
options
F. Yield goal
G. Pounds per acre
H. Limestone
suggestions
I. Special notes
pH • H+ ions in soil solution
• Indicates the level of active soil acidity
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Benefits of Proper pH
• Increased efficiency of fertilizers
• Reduced availability of Al & Mn
• Favorable microbial activity
• Better soil structure
• Increased longevity of legume stands
• Improved activity of certain herbicides
• Improved availability of soil nutrients
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Benefits of Proper pH Improved availability of soil nutrients
Limestone Puts Nutrients to Work
pH
(salt)
Nitrogen
%
Phosphorus
%
Potassium
%
4.0 30 23 33
4.5 53 34 52
5.0 77 48 77
5.5 89 52 100
6.5 100 100 100
Percent Nutrient Availability
Dr. Gene Stevens – Delta Center, Portageville, MO
• Effective Neutralizing Material (ENM)
• Rates the effectiveness of the limestone
• Grinding limestone finer improves its solubility and speeds up reaction with soil
• Smaller the particle size, the faster the action (higher ENM)
Ag Lime
• Lime is the most economical nutrient to apply
Ag Lime
• Effective Neutralizing Material (ENM)
– To determine the amount of limestone needed in
tons per acre, divide the ENM value on the soil
report by the ENM guaranteed by your ag lime
dealer
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Ag Lime
• Effective Neutralizing Material (ENM)
– To determine the amount of limestone needed in
tons per acre, divide the ENM value on the soil
report by the ENM guaranteed by your ag lime
dealer
EXAMPLE: If the soil test ENM requirement is 1395 and
the lime quarry guarantee is 420 pounds ENM per ton of
limestone, then you will need 3.3 tons of limestone per
acre (1395 ÷ 420).
Ag Lime
• Limestone is not very water soluble; therefore, it reacts slowly with soil
• May take as long as 1 year
• Incorporate limestone for more effective use
• Ag lime contains calcium carbonate, which is used to neutralize the pH
• Dolomitic Lime also contains magnesium, and is used on magnesium-deficient soils
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• The building block of proteins (enzymes),
chlorophyll, DNA, RNA
The Nitrogen CycleAtmospheric
nitrogen
Atmospheric
fixation
and deposition
Animal
manures
and biosolids
Industrial fixation
(commercial fertilizers)Crop
harvest
Volatilization
Denitrification
Runoff and
erosion
Leaching
Organic
nitrogen
Ammonium
(NH4)
Nitrate
(NO3)
Plant
residues
Biological
fixation by
legume plants Plant
uptake
Imm
obilization
Imm
obilization
Mineralization
Mineralization
Input to soilComponent Loss from soil
-+
Low Nitrogen
• Poor crop growth
• Stunted growth
• Reduced tillering
• Reduced crude protein
• Nitrogen deficiency causes an overall
yellowing of the plant with the lower leaves
yellowing and dying from the leaf tips inward.
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• Storage and transfer of energy – ATP & ADP
• Membranes
• DNA & RNA
The Phosphorus Cycle
Animal
manures
and biosolids Mineral
fertilizers
Crop
harvest
Runoff and
erosion
Leaching
(usually minor)
Organic phosphorus
•Microbial
•Plant residue
•Humus
Primary
minerals
(apatite)
Plant
residues
Plant
uptake
Soil solution
phosphorus
•HPO4-2
•H2PO4-1
Secondary
compounds(CaP, FeP, MnP, AlP)
DissolutionDissolution
PrecipitationPrecipitation
Mineral
surfaces
(clays, Fe and
Al oxides,
carbonates)
Wea
ther
ing
Wea
ther
ing
Adsorption
Adsorption
Mineralization
Mineralization
Immobilization
Immobilization
DesorptionDesorption
Input to soilComponent Loss from soil
Atmospheric
deposition
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A large portion of Missouri pastured are
low in plant available P
Percent of soil samples testing high in available phosphorus
Low phosphorus
• Poor crop growth
• Affects all aspects of growth – Maintenance and transfer of genetic code
• Critical for energy conversions in plant – Photosynthesis, ADP, & ATP
• Poor root development
• Poor seed development
• Affects early maturity / quick recovery
• Poor legume growth
• reduced survival and activity of N fixing
bacteria
Low Phosphorus
• Plants without adequate phosphorus levels
appear stunted, have reduced tillers, and a
poor root system.
Phosphorus
• Phosphorus effect on tall fescue yield
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0 lbs P/acre 12.5 lbs P/acre 25 lbs P/acre
Hay
Yie
ld (
lbs/
acre
)
0
1000
2000
3000
4000
5000
2001-02
2002-03
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200 100 0
200 50 100 0
Phosphorus
Low Bray-1 P 30 lb P/acre
Bray-1 P
Picture taken 3 years after P addition
Source: Dr. Dale Blevins and Dr. Kevin Bradley, MU
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• Enzyme activation
• Water relations
• Energy relations
The Potassium Cycle
Animal
manures
and biosolids
Mineral
fertilizers
Crop
harvest
Runoff and
erosion
Leaching
Soil solution
potassium (K+)
Plant
residues
Plant
uptake
Mineral
potassium
Fixed
potassium
Exchangeable
potassium
Input to soilComponent Loss from soil
• Nitrogen uptake
• Translocation
• Starch synthesis
Low Potassium
• Poor crop growth
• Inhibition through reduced enzyme activity
• Impaired water uptake
• Reduces root starch storage
• Reduces protein concentration in root
• Results in poor survival and slow shoot growth
• Reduced disease resistance
• Reduced winter hardiness
Potassium Deficiency
• Symptoms appear in the oldest leaves as
necrotic speckling along the length of the leaf,
and spreading toward the leaf margin.
Fertilizer Fact!! • To produce 1 ton of forage
– 35 - 60 lbs of Nitrogen
– 12 - 15 lbs P2O5
– 45 - 60 lbs K2O
Law of Minimum
Minimum
• Plant growth is controlled
NOT by the total of
resources available, but
by the scarcest resource
(limiting factor).
• Carl Sprengel, 1828
Justus von Liebig
Timing of P and K
• P and K are stable in the soil and will not move
off site when applied
• Fertilizer application can be made at any time
Timing of N
• N is mobile in the soil and has the potential to
move off site
• N fertilization should be done when the plant
has the capacity to respond
Nitrogen for Tall Fescue Hay
April August October June
Fora
ge
Yie
ld
Spring fertilization for Hay:
- apply nitrogen in mid March
- maximizes natural growth curve
Herd feed
requirement
Nitrogen for Tall Fescue Pasture
April August October June
Fora
ge
Yie
ld
Spring fertilization for Pasture:
- apply nitrogen in early May
- extends spring forage into July
- less response, higher potential value
Herd feed
requirement
Nitrogen for Tall Fescue Pasture
April August October June
Fora
ge
Yie
ld
Fall fertilization for Pasture:
- apply nitrogen in mid August
- increases and extends fall forage
- less response, higher potential value
Herd
forage
demand
Liquid Fertilizer Units per gallon of Material
N P2O5 K2O
Gallons to equal 50 lb
N
8-0-0-9 (10.1 ) 0.8 0.0 0 62.5
32% (11.1) 3.6 0 0 13.9
28% (10.6) 3.0 0 0 16.7
Source: John Jennings, University of Arkansas Extension
Liquid Fertilizers
Treatment
Ammomium NitrateUAN Urea U+Montys U+S90 U+FE Montys S90 FE
Yie
ld (
lbs
DM
/acr
e)
0
1000
2000
3000
4000
5000
6000
7000
8000
Evaluation of nontraditional fertilizers for bermudagrass yield - 2008
Ammonium
Nitrate
Liquid
Urea
Urea Urea +
Monty's
Plt Food
Urea +
Sea 90
Mineral
Urea +
Fish
Emulsion
Monty's
Plt Food
Sea 90
Mineral
Fish
Emulsion
Total of two harvests (7/28 & 10/17)
A
BBAB
B
C
C
CC
Bars topped by the
same letter are not
different at the 0.05 level
AN, Liq. Urea, & Urea applied at 75 lb/a N
Monty's Plt Food - 1.5 pints/a
Sea 90 Mineral - 2 lbs/a
Fish Emulsion - 4 gal/a
Untreated
Check
AB
Treatments applied on 6/27 and 8/5
Source: John Jennings, University of Arkansas Extension
• Amount nutrient required vs. amount in product
• Always ask for DATA!
• Beware of testimonials without data
-too much variability in farms, weather, etc.
• It’s OK to experiment, but make sure you have
a side by side comparison
Evaluating Nontraditional Fertilizers
Manure as Fertilizer
• Approximately 50-60% of the N in manure is available to plants if surface applied
• P levels are typically high
• K levels in manure are typically low and additional K fertilizer is often needed.
• TEST THE NUTRIENT CONTENT OF THE MANURE
• Rhizobia bacteria fix N
• 50-200 lbs N/Acre/year
• Lag time after planting for N fixation to occur
• N fixation is reduced or stopped if N fertilizer is
applied
• Need at least 25% stand for significant impact
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Legumes
73
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Nodulated Plants
Produce Nitrogen • Seeds should be inoculated to ensure fixation
Not inoculated Inoculated
Treatment Yield lb/acre
Tall fescue + red clover 11,100
Tall fescue + N
0 lb N/acre 3,900
90 lb N/acre 6,700
180 lb N/acre 9,900
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Yield of Tall Fescue & Clover vs.
Tall Fescue & Nitrogen
Source: Taylor Kentucky Agric. Ext. Ser. AGR-26
76
Nitrogen Fertilization of
Grass/Legume Mixes
0
5
10
15
20
25
30
35
0 25 50 100
% L
esp
edez
a
Lbs/acre N
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Species Differ in their Nutrient Requirements
Species Differ in their
Nutrient Requirements
Alfalfa
Red clover
White clover
Birdsfoot trefoil
Annual lespedeza
Cool-season grass
Warm-season grass
Very low Low Medium High
Soil Test Level for Persistence
Minimum Soil Test levels for legume
establishment and maintenance.
Legume Species pH P K
Alfalfa 6.5 30 300
Red Clover 6.0 25 250
White Clover 5.5 25 250
Birdsfoot Trefoil 5.5 20 225
Annual Lespedeza 5.0 20 200
Source: Missouri Grazing Manual p. 61
83
Fertilizing for Hay vs. Pasture
- Fertilizer
- Manure
- Legumes (N)
Inputs Nutrient Cycle
- Hay removes 80%
of nutrients
Hay Systems
3 tons of hay removal rates:
- 150 lb. Nitrogen
- 18 lb. P (40 lb. P2O5)
- 120 lb. K (145 lb. K2O)
Exports
Nutrient Removal Nutrient removal by harvest of major forages.
N P2O5 K2O
Forage --- lb/t dry matter basis ---
Alfalfa * 56 15 60
Annual Ryegrass 58 16 67
Bahiagrass 43 12 35
Bermudagrass 46 12 50
Bromegrass 36 13 59
Clover * - Grass 50 15 60
Fescue 38 18 52
Orchardgrass 50 17 62
Sorghum-sudan 40 15 58
Timothy 38 14 62
Vetch * 56 15 46
--- lb/t (67% moisture basis) ---
Corn Silage 8.3 3.6 8.3 * Legumes obtain most of their N from the air
Similar table found on p. 26 of Missouri Grazing Manual
Inputs Nutrient Cycle
Pasture Systems
Cow/calf pair, stocker removal rates
- 10 lb. Nitrogen
- 3 lb. P (7 lb. P2O5)
- 0.7 lb. K (1 lb. K2O)
Exports
Fertilizer
Manure
Legumes (N)
Feed
Beef
Calves
Your Cheapest Fertilizer Source
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Feeding Hay
“Fertilizes” Pastures
• 23 lb of N
• 9 lb P2O5
• 24 lb K2O
1000 lb bale of
grass hay
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One cow on hay for 100 days
lbs $
Available Nitrogen 25 20.75
Phosphate 21 11.13
Potash 73 37.96
$69.84
Assumes 30lb feed/day (1.5 tons fed)
Fertilizer value based on $0.83/lb N, $0.53/lb phosphate, $0.52/lb potash
(7/24/2012 at MFA, Cabool)
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93
Management needed to
distribute nutrients!
0
5
10
15
20
25
30
Unroll hay
Feeding area
Control
0
50
100
150
200
250
300
350
Unroll hay
Feeding area
Control
- 4-year study
- Chris Zumbrunnen, NE MO
So
il te
st P
(lb
s/A
)
So
il te
st K
(lb
s/A
)
94
Management needed to distribute
nutrients!
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Unroll hay
Feeding area
Control
- 4-year study
- Chris Zumbrunnen, NE MO
Yie
ld (
ton
s/A
)
95
Fertilizer Pays Better with
Efficient Grazing Management
• Continuous grazed systems
• 30% utilization of forage
• Animals consume 600 lb. of every ton of forage
• Management intensive grazing
• 50 to 70% utilization
• Animals consume 1,000 to 1,400 lb. of every ton of forage
Improved Manure Distribution
Improved Manure Distribution
Rotation Frequency
Continuous
14 day
4 day
2 day
Years to get 1 pile / sq. yard
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8
4-5
2
99
1. Use soil tests as tools for managing soil fertility
2. The forage must be fed before it will feed the
livestock
3. Manage soil pH to improve fertilizer efficiency
and legume persistence
4. Establish fertility levels adequate for target
species
Fertilization Strategies
100
5. Improve grazing management to improve nutrient
cycling, legumes, and grazing days
6. Distribute nutrients excreted by livestock evenly
over the pasture system
7. Split fertilizer by season to extend growth and
reduce hay need
8. Ask Questions!
Fertilization Strategies
101
Thank You
Questions?