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Title: MODEL-BASED TECHNIQUE TO DETERMINE VARIABLE RATE NITROGEN FOR CORN

Author
item PAZ, JOEL - IOWA STATE UNIVERSITY
item BATCHELOR, WILLIAM - IOWA STATE UNIVERSITY
item Colvin, Thomas
item Logsdon, Sally
item Kaspar, Thomas
item Karlen, Douglas
item BABCOCK, BRUCE - IOWA STATE UNIVERSITY
item PAUTSCH, G - IOWA STATE UNIVERSITY

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/22/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Past efforts to correlate yield in small sections of fields to soil type, elevation, fertility, and other factors in an attempt to characterize corn (Zea mays L.) yield variability has had limited success. 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 develop 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 in the field, the optimum nitrogen rate to maximize net return was computed for each grid through 22 years of historical weather data. These results were used to evaluate the economic benefit associated with variable rate nitrogen prescriptions.