Effect of organic and inorganic anions on availability of phosphorus applied through different phosphorus fertilizers to moong-bean grown in soil

The effect of the presence of different anions (oxalate, citrate, sulphate, and chloride) on phosphorus (P) availability from different P sources [rock phosphate (RP), single superphosphate (SSP), and diammonium phosphate (DAP)I in a P-deficient soil of Haryana (India) was studied. The moong-bean (Vigna radiata) was the test crop. Grain and straw yield of moong-bean, P uptake by grain and straw increased with increasing levels of P applied through three sources and in presence of different anions. The relative agronomic effectiveness (RAE) of soluble fertilizer (SSP and DAP) were much higher than water insoluble P (RP). The RAE of DAP in presence of anions was greatly affected by the type of anions. The percent utilization of added P generally increased with increasing P levels applied through RP but it decreased with increasing P levels when applied through soluble P sources (SSP and DAP). The values of P utilization for RP were smaller, even at highest P level, than for SSP and DAP recorded at any level. Grain and straw yield, total P uptake, acid percent P utilization from each source and P levels were highest in presence of oxalate ions and the values for these parameters decreased in order of oxalate, citrate, sulphate, and chloride.