Drainage Water Quality of Manure Application to Soybeans

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Drainage Water Quality of Manure Application to
Soybeans

• Matthew Helmers, PhD
• Assistant Professor and
• Extension Agricultural Engineer
• Department of Agricultural and Biosystems
  Engineering
• Iowa State University

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Issues

• Use of subsurface drainage has increased
  nitrate-nitrogen export to surface water bodies
• Long-term studies have been conducted to
  investigate the impact of liquid swine manure
  application on drainage water quality
• Recent questions have arisen regarding manure
  application on crop land going to soybeans
  primarily related to nitrate leaching

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Manure Application to Soybean

• Reasons for considering liquid swine manure
  application to soybean
• Low P and K tests
• Maintain surface residue cover for soil
  conservation limiting P runoff
• Potential to increase soybean yield even in soils
  with adequate P and K
• Allows access to more crop land for manure
  application
• Wider window for spring manure application

Iowa State University Agronomy Extension
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(No Transcript)
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Plot Sampling Layout
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Flow and sampling set-up
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Gilmore City Treatments 2001-2004 (Treatments
began Fall 1999)
All treatments in a Corn/Soybean Rotation
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Four-year Average Nitrate-Nitrogen Concentration
for Treatments at Gilmore City
Treatment means with different letters above the
bar are significantly (Plt0.05) different
35 increase in nitrate conc. comparing Fall
Manure to Fall Manure CS
Note Treatment N-application rates to corn (C)
and soybean (S) Fall Ammonia 150C 0S 150
rotation total Fall Manure 200C 0S 200
rotation total Fall Manure CS 150C 150S
300 rotation total
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Four-Year Average Crop Yield for Treatments at
Gilmore City
Note Treatment N-application rates to corn (C)
and soybean (S) Fall Ammonia 150C 0S 150
rotation total Fall Manure 200C 0S 200
rotation total Fall Manure CS 150C 150S
300 rotation total
Note Treatment means with different letters
above the bar are significantly (Plt0.05)
different
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Nashua Treatments 2001-2005 (Treatments began
Fall 1999)
Presently - Iowa DNR Manure Management Plans
allow manure application to soybeans at rate of
3.8 lb-N/bushel
All treatments in a Corn/Soybean Rotation
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Annual Average Nitrate-Nitrogen Concentration for
Treatments at Nashua
Note Treatment N-application rates to corn (C)
and soybean (S) Fall Manure 150C 0S 150
rotation total Fall Manure CS 150C 200S
350 rotation total
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Five-year Average Nitrate Concentration for
Treatments at Nashua (averaged over corn and
soybean phases)
Treatment means with different letters above the
bar are significantly (Plt0.05) different
80 increase in nitrate conc. comparing Fall
Manure to Fall Manure CS
Note Treatment N-application rates to corn (C)
and soybean (S) Fall Manure 150C 0S 150
rotation total Fall Manure CS 150C 200S
350 rotation total
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Five-Year Average Crop Yield for Treatments at
Nashua
Note Treatment N-application rates to corn (C)
and soybean (S) Fall Manure 150C 0S 150
rotation total Fall Manure CS 150C 200S
350 rotation total
Note Treatment means with different letters
above the bar are significantly (Plt0.05)
different
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Summary and Conclusions

• At comparable N-application rates of manure and
  commercial fertilizer similar nitrate-N losses in
  tile drainage
• Nitrate-N conc. in tile drainage increased when
  applying liquid swine manure at allowable
  N-application rates to both corn and soybean
  compared to N-application just to corn in a corn-
  soybean rotation
• Nitrate-N conc. increase of 35 when two-year
  N-application increased from 200 to 300 lbs
  N/acre
• Nitrate-N conc. increase of 80 when two-year
  N-application increased from 150 to 350 lbs
  N/acre

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Manure Application to Soybean Fields

• Dr. John Sawyer
• Associate Professor
• Soil Fertility Extension Specialist
• Department of Agronomy
• Iowa State University

Swine Manure Nutrient Utilization Project, Iowa
State University
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In-Season Liquid Swine Manure Application
Iowa State University Agronomy Extension
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Swine Manure Nutrient Utilization Project, Iowa
State University
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Preplant Liquid Swine Manure ApplicationAverage
Across 12 Varieties
Iowa State University Agronomy Extension
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Iowa State University Agronomy Extension
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Liquid Swine Manure Application to Soybean
Post-harvest 0-4 ft Profile Soil Nitrate
Swine Manure Nutrient Utilization Project, Iowa
State University
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Liquid Swine Manure and N Fertilizer Application
to Soybean Post-harvest 0-4 ft Soil Nitrate
Iowa State University Agronomy Extension
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Manure N-P-K Application and Soybean - Corn
Rotation Use
Iowa State University Agronomy Extension
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Liquid Swine Manure Application to Soybean

• No recommendation for N application
• P, K, and other nutrients can improve yield when
  soils are deficient
• Allows access to greater crop acres for manure
  application
• But, can result in P soil test buildup from high
  rate or frequent application
• Injection/incorporation into corn stalks can
  result in less soil erosion potential

Iowa State University Agronomy Extension
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Liquid Swine Manure Application to Soybean

• May result in yield improvement
• Due to manure N?
• Not predictable or consistent
• Does not offset manure-N value
• Can increase white mold disease and lodging
• Can increase residual soil nitrate and tile-flow
  nitrate-N concentration, especially with high
  manure rate

Iowa State University Agronomy Extension
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Questions and Comments

• Contact info
• Matt Helmers
• 209 Davidson Hall
• Iowa State University
• Ames, IA 50011
• 515-294-6717
• mhelmers_at_iastate.edu

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Frequency of Liquid Swine Manure Application to
Corn-Soybean Rotation
Iowa State University Agronomy Extension