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Current Nitrogen Fertilization Strategies for Corn in Nebraska

Current Nitrogen Fertilization Strategies for Corn in Nebraska. Richard Ferguson Bob Caldwell. 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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Current Nitrogen Fertilization Strategies for Corn in Nebraska

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  1. Current Nitrogen Fertilization Strategies for Corn in Nebraska Richard Ferguson Bob Caldwell

  2. 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 Nebraska Nitrogen Rate Algorithm for Corn NR = 35 + (1.2*EY) – (8*NO3-N) – (0.14*EY*OM) 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.

  3. 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).

  5. 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

  6. Nitrogen Fertilizer Use in Nebraska Primary Sources Nitrogen for all crops Nebraska Agricultural Statistics Service

  7. Chemigation: in-season whole-field N application

  8. Oct Oct Oct Oct Nov Nov Nov Nov Dec Dec Dec Dec Jan Jan Jan Jan Feb Feb Feb Feb Mar Mar Mar Mar Apr Apr Apr Apr May May May May Jun Jun Jun Jun Jul Jul Jul Jul Aug Aug Aug Aug 100 % 50 100 % 50 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.

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