Submitted to: ASAE Annual International Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 16, 2005
Publication Date: July 18, 2005
Citation: Sudduth, K.A., Drummond, S.T., Kitchen, N.R., Scharf, P.C. 2005. Real-time crop reflectance sensing to control variable-rate nitrogen application [abstract] [CDROM]. American Society of Agricultural Engineers Annual International Meeting. Abstract No. 051063. Technical Abstract: Research suggests that variable-rate nitrogen application based on within-season crop canopy reflectance sensing can improve nitrogen (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 and wheat fields and control N fertilizer application. In this paper we describe the design and implementation of the hardware and software control system. We document and compare the performance of two different reflectance sensors in this application, describe the performance of the overall system, and discuss field test results. The application system worked well when implementing N treatments in seven producer corn fields 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. The system was also used for winter wheat in 2005, where applicator-mounted sensor reflectance data was strongly related to vegetation indices calculated from aerial remote sensing images. Although the application system worked well for both corn and wheat, development of a control algorithm that optimizes N application within and among variable fields remains a challenge.