Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/23/2007
Publication Date: N/A
Technical Abstract: Excess nitrogen application on corn fields result in increased potential for nitrogen loss to ground or surface waters, while reducing the amount of nitrogen applied creates a risk of diminished productivity and lower yields. Crop canopy reflectance sensor technology for optimizing nitrogen application on corn addresses the issues of excess nitrogen application as well as the risk of reduced productivity. The overall approach of using active crop canopy reflectance sensors is to assess crop reflectance differences that are used to vary nitrogen fertilizer application. The reflectance from a non-nitrogen-limiting reference strip standardizes the reflectance from the application area. While the use of a non-nitrogen-limiting reference strip or multiple strips provides a mean of assessing inherent spatial variability related to factors affecting nitrogen stress, extra time and labor is needed at the beginning of the growing season to implement these reference strips. With crop canopy reflectance data collected from field-scale studies where multiple reference strips were implemented, simulations of in-season nitrogen need were analyzed to compare different alternative approaches to using a reference strip. One approach utilized a small area near the field entrance to determine a non-nitrogen-limiting crop reflectance value that could be used to guide nitrogen application for the entire study area. Another approach investigated soil electrical conductivity as a variable that could be correlated to reference strip variability and used to develop a non-nitrogen-limiting reference map for the study area. The goal is to develop alternative approaches to using a reference strip to reduce the extra time and labor needed in adopting crop canopy reflectance sensor technology.