Fertility Programs for Hay and Pasture

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Fertility Programs for Hay and Pasture
Fleming County Forage Meeting
Greg Schwab, Extension Soil Specialist UK
Department of Agronomy
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Soil Fertility and Forage Production
Key Components
Goal Stand Longevity
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Soil Sampling
How often???

• Field Uniformity
• Slope
• Drainage
• Cropping history

A sample should not represent more then 20 acres
Sampling Depth 4 for no-till 6 for conv.-till
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Sample in Management Zones
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The effect of soil pH on the activity of soil
micro-organisms, availability of plant nutrients,
and occurrence of toxic elements
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Extremely important to make sure that soil pH is
correct prior to establishment
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UKs Fertilizer Recommendations based on the
Sufficiency model
Probability of response based on field research
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Nitrogen Fertilizer and Forage Production

• Research shows that dry matter can be
  increased from 1 ton/a with no N up to 4 ton/a
  with 200 lbs/a.
• Late winter/early spring N applications
  increase growth so grazing can begin about 2
  weeks earlier

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Nitrogen Fertilizer Source

• All sources of N are equal until about May
• After May 1st use efficiency of urea drops to
  50 to 75 of ammonium nitrate because of
  ammonium volatilization
• UAN (28) efficiency will be 75 to 90 of
  ammonium nitrate
• Consider urease inhibitor

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Not Inoculated
Inoculated
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A mixture of grass with at least 25 legumes will
have a similar yield as pure grass 300 lbs N/a
N Value of the legume 300 x 0.45 135/a
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Potassium Deficiency
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Fertilizer Recommendation
Each ton of alfalfa contains 14 lbs/ac P2O5 50
lbs/ac K2O
Each ton of grass legume hay contains 35 lbs/ac
N 12 lbs/a P2O5 53 lbs/a K2O
For a 5-6 ton/ac alfalfa crop 75-90 lbs
P2O5 250-300 lbs K2O
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UKs Phosphate and Potash Recommendations for
Grass/legume Hay
New Seedings Established Stands
.lbs per acre.
Soil Test Level P2O5 K2O P2O K2O
V. High (above 450K) -- 0 0 0
High (60P, 300-450K) 0
0-120 0 0-120
Medium (28-60P, 200-300K) 30-110 130-270
30-70 130-270
Low (lt 28P, lt200K) 120-160
280-360 80-120 280-360
Higher Yields- fields should be sampled every
year for yields above 5 T/A.
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P and K recommendations for cool-season grasses
have not changed.
New Seedings
Soil Test P 0 - 60 recommendation 0 120 Soil
Test K 0 300 recommendation 0 - 80
Established Stands
Soil Test P 0 - 60 recommendation 0 120 Soil
Test K 0 300 recommendation 0 - 180
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Why we dont just recommend removal rates of
potassium
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Indiana Research Indicates that there is a
seasonal K response
1999 Harvest 4 Yield
2000 Harvest 1 Yield
LSD0.12
LSDNS
(Berg, et al., 2002)
K use efficiency can be increased by applying ½
fertilizer before last harvest and ½ after first
harvest
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Photo credit J.J. Volenec
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Why we dont just recommend removal rates of
potassium
Luxury Consumption
K tissue concentration can be as high as 4.5
Rather than 250-300 lbs/a A 5-6 ton/ac alfalfa
crop 450-540 lbs K2O Savings 55/acre
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Micronutrients
Fe, Cu, Mn and Zn no measurable yield response
in Kentucky
Boron (B) often a limiting nutrient of
alfalfa Biannual applications after the seeding
yr. 1.5-2.0 lbs of B/ac Borated fertilizer or
fertilizer borate
Molybdenum (Mo) deficiencies often occur when
soil pH lt 6.2 Apply 1 lb sodium molybdate/ac
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Boron Deficiency
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Forage Summary
pH probably single most important factor.
New Seedings P and K applied before seeding.
Established Stands P and K improves stand
longevity.
Avoid applying K in late fall or early spring.
Spring applications should be made after the
first cutting.
Manure applications prior to planting or during
later years of the stand
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Questions/Comments