OnFarm Approaches to Conservation Practices and Nutrients

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On-Farm Approaches to Conservation Practices and
Nutrients

• Jerry L. Hatfield
• 515-294-5723
• hatfield_at_nstl.gov
• Jerry.hatfield_at_ars.usda.gov

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Background

• Fields are comprised of a range of soils
• Soils vary in their water holding capacity and
  their response to tillage and N

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Field-Scale Variation in Plant Growth and Yield
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Soil Degradation Spiral
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Soybean Production Field May 2005
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Soybean Production Field June 2005
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Soybean Production Field Early August 2005
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Soybean Production Field Late August 2005
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Yield Correlation with RS data
SAVI 3rd flight
SAVI 4th flight
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Dallas South Yields
Data comparisons from last two strips
North
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Spatial Patterns within Fields
Dallas South
EM-38 Yield
Reflectance
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N-Yield Response
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(No Transcript)
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Study Site
Corn Field in Central Iowa
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Site 2005 Corn FieldEnergy Balance
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Water Use Efficiency
Nutrients
Crop Biomass or Grain Yield
Soil Management
Residue
Water Use
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Water Use Efficiency
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Water Balance 1998
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Water Balance 1999
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Water Balance 2000
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Solar Radiation
Carbon Water Nitrogen
Soil surface
Key Processes
Photosynthesis Precipitation
N Fixation Respiration
Evaporation Mineralization Org Matter
decomp Infiltration
Denitrification Plant decomposition Runoff
Plant decomposition
Percolation
Cycles interact over time and space with
different rates
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Short- vs Long-Term Effects of Tillage

• Short-term
• Increase drying (0.5 inch of water loss per pass
  in spring)
• Incorporate residue, nutrients, manure
• Increase infiltration of water
• Reduce compaction

• Long-term
• Reduce soil organic matter content
• Decrease water holding capacity
• Increases the potential risk to crop production
  problems

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Indicators of Tillage Responses

• Yield
• Profit
• Breakeven costs
• Efficiency

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Yield 2002
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Yield 2003
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Yield 2004
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Nitrogen Use Efficiency
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Water Use Efficiency
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Light Use Efficiency
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Corn Production Costs
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Soybean Production Costs
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Break Even Production Costs

• Corn (3.00 per bu)
• Fall Tillage - 53 bu/A
• Fall Strip 46 bu/A
• Spring Strip 44 bu/A
• Soybean (5.00 per bu)
• Fall Tillage 26 bu/A
• Fall Strip 23 bu/A
• Spring Strip 21 bu/A

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Extending Fields to Watersheds

• Example from the Raccoon River Watershed

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Nitrate Trends
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Nitrate Concentrations
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N Load/N Applied
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Nitrate Loads vs Loss
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Fertilizer Application
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Soybean Production
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Change in Animal Production
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Change in Land Use
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Implications

• Watershed impact may be greater from changing
  crop rotations than management scenarios with N
  rates and timing
• Strategic placement of crops with different water
  use patterns than corn or soybean will have a
  positive impact

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Solar Radiation
Carbon Water Nitrogen
Soil surface
Key Processes
Photosynthesis Precipitation
N Fixation Respiration
Evaporation Mineralization Org Matter
decomp Infiltration
Denitrification Plant decomposition Runoff
Plant decomposition
Percolation
Cycles interact over time and space with
different rates