Tuesday, November 6, 2007 - 1:00 PM
153-7

Field-Scale N Application Using Crop Reflectance Sensors.

Kenneth Sudduth1, Newell R. Kitchen2, Peter C. Scharf3, Harlan L. Palm3, and D. Kent Shannon3. (1) USDA-ARS Cropping Systems & Water Quality Research Unit, USDA-ARS, 269 Agricultural Engineering Bldg, Columbia, MO 65211, (2) Cropping Systems & Water Quality Research Unit, USDA-ARS, 269 Agricultural Engineering Bldg, Columbia, MO 65211, (3) University of Missouri, Columbia, MO 65211

Research suggests that variable-rate nitrogen application based on within-season crop canopy reflectance sensing can improve N use efficiency. The overall objective of this project was to use commercial dual-wavelength active reflectance sensors on a fertilizer applicator to quantify reflectance variations in corn fields and control N fertilizer application. In this work, we describe the design and implementation of the hardware and software control system. We document the performance of two different reflectance sensors in this application, describe the performance of the overall system, and discuss three years of field test results. The application system worked well when implementing N treatments in 2004. However, yield and N use efficiency results were mixed, because in some cases our control algorithm did not apply sufficient N for the near-ideal growing conditions. In 2005, drought conditions at most test sites masked any yield response to N application. In 2006, variable-rate N application resulted in improved profitability at most test sites. Development of a control algorithm that optimizes N application within and among variable corn fields remains a challenge. 

Back to Symposium--New Management Practices for Fertilizer N/Div. A09 Business Meeting
Back to A09 Professional Practitioners

Back to The ASA-CSSA-SSSA International Annual Meetings (November 4-8, 2007)