|Scharf, Peter - UNIVERSITY OF MISSOURI|
|Palm, Harlan - UNIVERSITY OF MISSOURI|
|Shannon, D. - UNIVERSITY OF MISSOURI|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 8, 2007
Publication Date: November 5, 2007
Citation: Sudduth, K. A., Kitchen, N. R., Scharf, P. C., Palm, H., Shannon, D. K. 2007. Field-Scale N Application Using Crop Reflectance Sensors [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. ASA-CSSA-SSSA Annual Meeting. Nov. 4-8, 2007, New Orleans, LA. Paper No. 153-7. Technical Abstract: 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.