Phosphate Uptake of Corn As Influenced By Applications of Phosphate-Enhancing Polymers.

Fertilizer-applied soil phosphate (P) has limited availability for crop uptake because of strong retention of this macronutrient by soil solids. AVAIL® is a copolymer based soil additive developed to enhance plant availability of P, but its effectiveness in improving crop performance is highly variable. The objective of this study was to evaluate plant uptake of P in relation to soil-applied concentrations of the AVAIL® copolymer and P application rates. Soil materials were collected from a P-deficient agricultural field in the Coastal Plain region of North Carolina, which was mapped as Goldsboro soil (Aquic Paleudult with a sandy loam texture). The soil materials were treated with varying inputs of AVAIL® (0 to 200% of the estimated P sorption capacity) and P (51 and 67 kg P₂O₅ ha^-1) levels before packing them in greenhouse containers in three 5-cm layers. The top and bottom layers received only N fertilizer with no P, whereas the middle layer received the AVAIL® copolymer and P treatments with N. Corn planted in each pot were monitored in a 3-week period with watering to field capacity. Corn P uptake and growth will be presented as a function of co-added AVAIL® and P. Results of this study will determine whether soil-specific rates of AVAIL® and P applications would increase the effectiveness of this polymer in the field.