Increasing Phosphorus Use Efficiency with Organic Acids: Movement of P Through Soil.

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.