Sensor Based Variable Rate Harvest Aids

Variable rate application of harvest aids could be a cost cutting means for cotton producers in the southern Great Plains.  One method that has been proposed for variable rate application is using crop sensors to estimate percent open bolls and current defoliation level.  Small plots were used to determine the relationship between the normalized difference vegetative index (NDVI) measured with sensors and the percentage of open bolls and nodes above cracked boll (NACB). This relationship was the basis for a variable rate prescription used in field trials.  A cotton field in southwest Oklahoma was divided into three replications of four plots.  This was a 2x2 factorial experiment with application method (uniform/variable) and input (PGR/DEF) as the treatments.  This combination resulted in four test plots and allowed possible interaction of variable rate PGR and defoliant. This study was conducted on one field in 2008 and two fields in 2009.