Improving the Efficiency of Phosphorus Fertilizer with the Use of AVAIL.

Crop recovery of applied phosphorus (P) fertilizer can be quite poor during the season of application. Recently Specialty Fertilizer Products has developed and patented a maleic-itaconic co-polymer, AVAILŽ, which can be used as a coating on granular P fertilizer or mixed into liquid P fertilizers. The polymer sequesters antagonistic cations out of the soil solution, keeping more P fertilizer available for plant uptake. Experiments were conducted in Kansas with corn (zea mays L.) and in west Tennessee with cotton (Gossypium hirsutum L.) to evaluate the effectiveness of this product. In the corn experiment three rates of P were applied to give 22, 44 and 66 kg ha-1 P2O5, each with and without AVAILŽ. In the cotton experiment only two rates of P2O5 were used, 34 and 68 kg ha-1. Unfertilized check plots also were included in the experiments. In both sets of experiments, P as mono-ammonium phosphate (11-52-0), with and without AVAILŽ was broadcast on the soil surface 10-14 days prior to planting. In both experiments, early season dry weight, plant P uptake and crop yield were increased by the addition of AVAŽIL to P fertilizer. Influencing the microenvironment around the fertilizer granule proved to have a significant benefit to the availability of applied P fertilizer resulting in significant yield increases.