Evaluation of the Efficiency of Partially Acidulated Phosphate Rock in Augmenting the Maize Productivity in Acid Soil

Abstract

Phosphorus rock (RP) reserves are finite and non-renewable, and coupled with the low use efficiency, which leads to significant and irreversible environmental losses. Controlled-release fertilizer technologies, which synchronise the phosphorus release from fertilizers with crop nutrient demand, offer a promising solution to mitigate phosphorus losses and enhance fertilizer use efficiency. The present investigation with maize as test crop was undertaken to evaluate the efficiency of partially acidulated phosphate rock (PAPR) blended with DAP in enhancing the yield, P uptake and recovery as compared to sole application of DAP, PAPR, and untreated PR. The vanado-molybdo phosphoric yellow colour complex in nitric acid medium method was used to estimate the P content. The Result of the study revealed that the fertilizer mixture improved the dry matter accumulation by 12% more as compared to PAPR. The P uptake was found to be 6% more compared to DAP. The relative agronomic efficiency and apparent crop recovery were found to be 107% and 54% respectively, which depicts the role of PAPR as slow released fertilizer. The alkaline phosphatase activity was found to be minimal in P-treated soil, indicating the presence of residual P in the soil. The post-harvest soil P indicates a strong residual nature with an ability to supply P to the succeeding crop.  It is recommended to use DAP and PAPR in 50:50 proportion to reduce the DAP dependency and simultaneously improving the crop productivity.