Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/11/2002
Publication Date: 11/11/2002
Citation: SCHARF, P.C., LORY, J.A., KITCHEN, N.R., SUDDUTH, K.A., DAVIS, J.G. SPATIAL VARIABILITY OF OPTIMUM N RATE FOR CORN. AGRONOMY ABSTRACTS. 2002. CD-ROM (UNPAGINATED). AMERICAN SOCIETY OF AGRONOMY, Madison, WI. Interpretive Summary:
Technical Abstract: Applying only as much N fertilizer as is needed by a crop has economic and environmental benefits. Small plot research has shown that fields can differ substantially in their need for N fertilizer, but the amount of within-field variability is not well understood. Our objective was to characterize the spatial variability of corn N need in production corn fields. Experiments were conducted in three major soil areas (Mississippi delta alluvial, deep loess, claypan) over two years. Treatments were field-length strips of discrete N rates from 0 to 280 kg N/ha. Yield data were partitioned into 20-m increments and a quadratic-plateau function was used to describe yield response to N rate for each 20-m section. Optimum N fertilizer rate was highly variable in all six experimental fields, with an average standard deviation of 56 kg N/ha. Our results suggest that uniform N applications result in large areas with excessive and/or insufficient N. Further attempts to develop systems for predicting spatially variable N needs are justified in these production environments.