Improving Phosphorus Use Efficiency with Organic Acid Complexation: Corn.

Phosphorus (P) fertilizer is used abundantly to maximize growth of crops and other plants. Reduction of P fertilizer is warranted, as it is the primary source of nutrient pollution in surface waters (eutrophication leading to hypoxia) and is derived from non-renewable mineral resources. A six-week glasshouse study was conducted to determine the effects of combining a humic/fulvic acid (Carbond® P) with P fertilizer on young maize (Zea maize L.) plants. An untreated control was compared to both ammonium polyphosphate (APP; 34% P₂O₅) and Carbond® P (24% P₂O₅) at 7.9, 24, 71, and 173 kg ha^-1_, applied diagonally (45^o), 7 cm below seed. On average, the Carbond® P treated plants were 5 cm taller, had 12% more chlorophyll), and had 14% thicker stems than APP treated plants. The Carbond P treated plants had 40 and 64% more dry matter yield than the APP plants at the two lowest rates. These growth increases were likely due to improved P uptake (43-56% more P) despite APP having one-third less total P applied than the Carbond® P. No differences between P sources were observed at the highest rate. Both fertilizers resulted in significant increases for all measured parameters over the control. These results suggest that at least 30% less P can be utilized when using Carbond® P in place of APP; with net increases in P uptake by maize plants and resulting in enhanced growth. Further work is needed to evaluate season-long impacts, as well as refined recommendations regarding P fertilizer reduction possibilities.