Relationships Between Cotton Nitrogen Status and Sensor Based Readings

Previous research has shown that cotton yields can vary across the landscape based on the management system utilized; however, typcial N fertilizer rates for cotton are applied uniformly across the field.  Sensor technology previously utilized in other crops can potentially quantify the N status of cotton and related sensor output to an N recommendation that will vary across the field and simultaneously improve cotton yields and profitability.  An experimental site was established in a 22 ac. field in the Coastal Plain consisting of Typic and Aquic Paleudults that had management systems in place for 9 years.  A split plot design was utilized with main plots consisting of two soil management systems (conventional-CT and conservation-NT) and split plots of 4 N rates (0, 40, 80, 120 lb/ac) with six replications of 12-ft. strip-transects (4-row widths) across the field that intersect management zones.  At pre-determined sampling points (12 x 60 ft. grids stratified within each management zone) 25 upper most mature leaves will be collected along with SPAD meter readings, plant heights, sensor measurements, and 1 m of whole plant biomass from the same pre-determined locations across landscape positions around 1^st square and mid-bloom.  Seed cotton yield will be determined across the field with a combine equipped with GPS and yield monitor.