Improving Phosphorus Nutrition of Cotton

Phosphorus (P) fertility can be a problem in crop production. In the year of application, as little as 25% of the applied P fertilizer may be available for crop uptake. On high pH soils P can be tied up by calcium and magnesium and on low pH soils by aluminum and iron. Cool soils that are typically present in reduced and no-tillage productions system can further depress root growth and P uptake, even on soils not low in available P. AVAIL fertilizer additive may  increase P availability and yield of crops by sequestering metal cations out of the soil solution. Experiments were conducted during the years 2010-2013 at one location and during 2012 and 2013 at another location in West Tennessee to evaluate AVAIL treated P fertilizer for cotton production. Treatments included two rates of applied P fertilizer (MAP) with and without AVAIL. A no-P check was also included. Treatments were replicated four times. Fertilizer was applied broadcast on the soil surface in a reduced-tillage production system 2 weeks prior to planting in mid-April each year. At the first location, AVAIL treated MAP fertilizer increased early season growth, P uptake and yield of cotton all three years of the experiment. When averaged over P rates, yield increase due to AVAIL was over 130 lbs. of lint cotton per acre. At the second location AVAIL also increased growth, P uptake and yield of cotton, although yield increases were not as dramatic as at the first site. In these experiments the use of AVAIL did prove beneficial in improving P efficiency and yield of cotton.