Increasing Phosphorus Solubility and Uptake Efficiency with Organic Acids.

Phosphorus (P) fertilizer is essential for crop production, but reductions are warranted to conserve resources and minimize environmental impacts. Two studies were conducted to evaluate CarbondŽ P against traditional ammonium polyphosphate (APP) and monoammonium phosphate (MAP) fertilizers. Flux of P through soil was evaluated using soil columns with fertilizers applied either as a band or mixed with three soils at 20 or 80 kg P₂O₅ ha^-1. Mobility of P was evaluated at 24, 48, 110, and 365 days after application by applying ~2 pore volumes of water through the soil columns. CarbondŽ P consistently had significantly greater P flux across all soil types and application rates for the banded application. For applications mixed with soil, CarbondŽ P and MAP had greater solubility than APP at 24 days after application, but by the later evaluation dates the CarbondŽ P was significantly higher than both. A glasshouse study was conducted on corn (Zea maize L.) with CarbondŽ P compared to an unfertilized control and APP at 6, 18, 54, and 162 kg P₂O₅ ha^-1 applied 5 cm below and 5 cm to the side of the seed. On average, the CarbondŽ P treated plants were 5 cm taller, had 12% more chlorophyll, and 14% thicker stems than APP treated plants for all but the highest rate. The Carbond P treated plants had significantly greater (40-64%) dry matter yield than the APP plants at the lower rates as well. These growth increases were likely due to improved P uptake (43-56% more P). No differences between P sources were observed at the highest rate. These results suggest that at least 30% less P can be utilized when using CarbondŽ P in place of APP; with net increases in P uptake by corn plants resulting in enhanced growth.