Agronomic Effectiveness of Acidulated Phosphate Fertilizers with Different Water Solubility

There is a high demand of P fertilizers in Brazilian agriculture, where the most common sources in use are acidulated phosphates. Due to the high P fixation capacity and low P levels of Brazilian soils in general, soluble P fertilizers have always been preferred for their high agronomic effectiveness. Recently, Brazilian legislation allowed the use of P fertilizers with low water solubility, but field trials are still needed to evaluate the effectiveness of such products. This project aims to study the agronomic effectiveness of four P fertilizers (acidulated phosphates) varying in water solubility (85, 70, 60, and 50%) for soybeans in an Oxisol in the Cerrado of Brazil. Results from the first year of this study suggest the same agronomic effectiveness for P fertilizers with water solubility higher than 60%, but lower effectiveness for the source with 50% water solubility. Therefore, the use of acidulated phosphates with lower water solubility (50%), compared to the currently used source with 85% water solubility, may be an alternative for Brazilian agriculture. This is a three-year project, and valuable and more conclusive results will be possible with time. Brazil-59

IPNI-2011-BRA-59