Evaluation of the Yield Potential Based Nitrogen Fertilization Optimization Algorithm in Cotton.

The use of remote sensor in cotton production has become a hot topic within the industry over the last few years.  Most of the focus has been on improving the application of plant growth regulators and harvest aids.  There has been a great deal of work on sensor based N management in cotton but little has made it to the producer level. The potential effect of sensor based N management on cotton production is great.  When N management is optimal, the need for added inputs such as growth regulators and harvest aids is dramatically reduced.  Recently, a nitrogen fertilization optimization algorithm was developed for cotton at Oklahoma State University that bases the recommended N rate upon a yield prediction model.  The process implements the use of a reference strip, which is an area in the field that has had N applied to a level which is high enough to support maximum yield levels.  This study implemented the new algorithm and compared it against traditional N recommendations and rates.  Replicated treatments were implemented in multiple trials in several locations across Oklahoma.  Sensor readings were collected with a GreenSeeker™ sensor from each plot multiple times between 30 and 90 days after planting.  Topdress N fertilizer was applied as UAN (28-0-0) during the early to mid bloom stages.   A sensor based nitrogen rate calculator that utilized the algorithm implemented in this trial is available online at www.nue.okstate.edu.  Producers and consultants can access this website enter the number of days from planting to sensing and the sensor readings and the algorithm will generate a recommended N rate prescription for each field that has a reference strip.