Sitespecific Nutrient Management

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Site-specific Nutrient Management
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• Status of SSNM
• Development of fertilization relationships
• SSToolbox procedures

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• Adoption by US corn producers-1996
• Technology Farm Acres
• soil grid map 7.1 15.8
• VRT fert. 3.7 8.4
• yield monitor 5.5 15.6
• yield maps 3.9 12.4

Source Daberkow and McBride, 1999
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TX Variable Rate Fertilization

• Available only in a few regions
• Use grid sampling at 2.5 - 4 acre per sample
  resolution
• Costs vary by supplier 2-3/acre
  for sampling, 0.50-3 for application
• Net returns 2-15/acre

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Variable Rate Application Services
Cargill VRT (95) Poole VRT (97)
Coop VRT (97)
Terra-VRT capability
Terra-grid sampling
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Fertilization Strategies

• Start with regional recommendations
• Refine for local conditions using site
  information and strip testing
• Evolve strategy over time

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SSToolbox Procedures

• Edit product list to include products to be used
• Develop equation to incorporate fertility
  relationships
• Create necessary input themes
• Apply equation
• Export application map