Current Nitrogen Fertilization Strategies for Corn in Nebraska

1
Current Nitrogen Fertilization Strategies for
Corn in Nebraska

• Richard Ferguson
• Bob Caldwell

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Nebraska Nitrogen Rate Algorithm for Corn
NR 35 (1.2EY) (8NO3-N) (0.14EYOM)
EY Expected yield (bu/acre) NO3-N Root zone
soil residual nitrate-N (ppm) OM Soil organic
matter () Additional credits for legumes,
irrigation water and manure.

• Strengths
• Fairly extensive research database
• Goal of minimizing nitrate leaching below root
  zone

• Weaknesses
• Reliant on accurate preplant soil testing
• Developed at yield levels 200 bu/acre

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Mid-Nebraska Demonstration Project N Rate
Response Over Years
4
Mid-Nebraska Demonstration Project

• N recommendation algorithm under-recommended N
  approximately 14 of the time (24 of 170 sites
  from 1990 1997, at which REC yield was
  statistically greater than REC yield).
• N recommendation algorithm over-recommended N
  approximately 52 of the time (88 of 170
  sites where REC- yield was statistically the same
  as REC yield).

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Nebraska Fertilizer Nitrogen Use Efficiency for
Corn
Statewide average corn yield for grain, and
surveyed average N rate irrigated and
dryland Nebraska Agricultural Statistics Service
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Nitrogen Fertilizer Use in Nebraska Primary
Sources
Nitrogen for all crops Nebraska Agricultural
Statistics Service
7
Chemigation in-season whole-field N application
8
Producer Approaches to N Timing for Corn
NH3
100
UAN
Fall NH3

50
Preplant NH3
100
Sidedress

50
Fertigation
9
Summary

• Current N recommendations for corn in Nebraska
  have led to measured increases in N use
  efficiency and reductions in groundwater nitrate
  concentrations.
• Current approach
• Relies on accurate preplant soil sampling.
• Is not sensitive to application timing ie
  increased efficiency with fertigation.
• May not be valid for yield levels above 220
  bu/acre.