Midseason Nitrogen Recommendation in Rice Using Remote Sensing Technology.

Determining the right rate of midseason nitrogen (N) fertilizer is a key component to improve N use efficiency and economical return in rice production.  Nitrogen management based on remote sensing technology has been intensively examined in several crops such as wheat and corn. The objective of this study was to evaluate the performance of midseason N fertilization rate in rice based on predicted yield potential and response index using normalized difference vegetative index (NDVI). Nitrogen response trials using Catahoula variety were established from 2008 to 2010 at different sites in Louisiana and Mississippi.  Grain yield, nitrogen use efficiency (NUE), and economical net return were compared between plots which received  fixed N and sensor-based N rate in 17 fields.  Sensor-based N rate recommendation had higher grain yield in 9 out of 17 fields. About 65 % of fields showed higher economical net return and NUE using sensor-based N rate recommendation compared with fixed N rate.  The lack of effectiveness of sensor-based N recommendations in some fields can be addressed by further refinement of the algorithms used for projecting rice yield potential and response to N.