Start Date: Feb 27, 2007
End Date: Sep 30, 2011
Objective 1 a. At a network of field sites managed by ARS and university scientists, sensor assessments, chlorophyll meter readings and grain yield data will be collected from corn receiving different rates and timings of N fertilizer to determine the most appropriate 1) distance from canopy to position sensors, 2) phenological growth stage, and 3) vegetation index for maximum sensitivity in assessing variation in corn canopy greenness or N status as well as grain yield response. b. Data collected from network field studies will be used to develop a robust algorithm that can be used to convert sensor readings into appropriate in-season N application rates for various corn vegetative growth stages that improves fertilizer N use efficiency. c. Through additional on-farm studies, a decision aid will be developed that uses apparent electrical conductivity, soil color images, and yield maps to incorporate soil- and climate-based adjustments to the basic sensor algorithm to customize N application recommendations for site-specific conditions. Objective 2: Field studies will be conducted to identify optimal irrigation, N fertilizer, and disease management strategies utilizing winter wheat in relay crop schemes to remove excess nitrate from the soil system and maintain economic viability.