137-5 Corn Yield and N Responses in Recent North Carolina Field Tests Vs Published Nitrogen Rate Recommendations.

Poster Number 2021

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Nitrogen Soil Fertility and Management

Monday, November 4, 2013
Tampa Convention Center, East Exhibit Hall

Thomas J. Smyth, North Carolina State University, Raleigh, NC, Carl R. Crozier, 207 Research Station Road, North Carolina State University, Plymouth, NC, Deanna L. Osmond, PO Box 7620, North Carolina State University, Raleigh, NC and Karl Shaffer, Shaffer Soil Consulting, Pittsboro, NC
Abstract:
Nitrogen (N) application rates that meet the USDA NRCS 590 Nutrient Management Standard are established through a table consisting of realistic yield expectations (3 of the best 5 years of yields; RYE), N factor (lb N per unit yield), and N application rate (RYE * N factor).   Corn data from the RYE table were compared with results from 72 recent corn N rate experiments at field sites across North Carolina. Some response to N fertilization was measured at all but 4 locations, and a maximum yield was documented for 57 of the sites. Averaged across all sites, maximum grain yield was approximately 20% higher than the published RYE values. Since optimum N fertilizer rates from these trials were almost identical to table rates but yields were higher, actual corn N efficiency (N factor) was improved; less N was required per unit grain in the field experiments than in the standard N-rate table. Additional trends noted in N efficiency: irrigated corn required more N per unit grain than did non-irrigated corn, and corn following corn required more N per unit grain than if corn followed soybean. Even with recent increases in grain yield potential, recommended N rates should not be increased for non-irrigated corn, because N efficiency has also improved. Data for the nitrogen rate table were collected approximately twenty years ago; based on the results from this study, periodic updates to yield potential and N efficiency values will be needed.

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Nitrogen Soil Fertility and Management