Effects of Phosphorus Fertilizer Placement and Rate on Yield and Fiber Quality in Arizona Cotton Production Systems

Efficiency with respect to fertilizers is increasingly important.  This work summarizes two years of experiments investigating the practice of precise placement of phosphorus based fertilizers in an effort to improve efficiency.  Sub-inch accuracy GPS systems allow for placement of seed directly over a pre-plant banded phosphorus application.  The ability to return to that exact location in subsequent years may enhance exploitation of the banded phosphorus application for more than one year.  It also may allow for decreased rates of application while still maintaining yield.  The technique of precise banding of phosphorus is compared to a traditional side-dress application.  Varying application rates from 0 to 100 pounds of P2O5 per acre is also evaluated within each application technique.  Yield and fiber quality is examined along with residual soil phosphorus levels for each treatment.  The ultimate idea behind this work is to utilize technology that most growers have (sub-inch accuracy GPS) to improve efficiency with respect to fertilizer applications.