Model-based technique to determine variable rate nitrogen for corn
1999
Paz, J.O. | Batchelor, W.D. | Babcock, B.A. | Colvin, T.S. | Logsdon, S.D. | Kaspar, T.C. | Karlen, D.L.
Past efforts to correlate yield from small field plots to soil type, elevation, fertility, and other factors have been only partially successful for characterizing spatial variability in corn (Zea mays L.) yield. Furthermore, methods to determine optimum nitrogen rate in grids across fields depend upon the ability to accurately predict yield variability and corn response to nitrogen. In this paper, we developed a technique to use the CERES-Maize crop growth model to characterize corn yield variability. The model was calibrated using 3 years of data from 224 grids in a 16 ha field near Boone, IA. The model gave excellent predictions of yield trends along transects in the field, explaining approximately 57% of the yield variability. Once the model was calibrated for each grid cell, optimum nitrogen rate to maximize net return was computed for each location using 22 years of historical weather data. Results show high spatial distribution of optimum nitrogen fertilizer prescription for grids across the field. Grid-level nitrogen fertilizer management used lower amounts of fertilizer, produced higher yields and was more profitable than either transect- or field- level(single rate) fertilizer application.
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