Oxalic-acid-treated low-grade rock phosphate can supplement conventional phosphorus fertilizer to grow wheat in Alfisol

Phosphorus (P) fertilizers are produced from high-grade rock phosphates (HGRPs). The reserve of HGRP is finite and non-renewable. We are rapidly shrinking this reserve, by producing P fertilizers. This fact establishes the need of utilizing low-grade rock phosphates (LGRPs) for growing crops. In this experiment, LGRP was treated with 0.5 M oxalic acid solution. The oxalic-acid-treated LGRP was used to supplement chemical P fertilizer in incubation as well as pot experiments in Alfisol. During incubation experiment, oxalic-acid-treated LGRP treatment (T 3 ) significantly increased soil available P as compared to control (T 1 ) and untreated LGRP (T 2 ) treatments. Pot study revealed that under DAP+ oxalic-acid-treated LGRP treatment (T 4 ), oxalic-acid-treated LGRP (@60 mg P 2 O 5 kg -1 ) supplemented 50% DAP without hampering wheat yield and P uptake, at the same time maintained significantly higher total P, inorganic P, organic-P, Ca-P, saloid P and statistically at par available P, dehydrogenase, acid and alkaline phosphatase activities as compared to DAP treatment (T 3 ) at all the growth stages of wheat. So, it can be inferred that 0.5 M oxalic acid solution treatment can be useful to utilize LGRP as supplemental P source to grow wheat. Oxalic-acid-treated LGRP (@60 mg P 2 O 5 kg -1 ) can successfully supplement 50% of the chemical P fertilizer for growing wheat. It also improves soil P fertility and sustains dehydrogenase, acid phosphatase and alkaline phosphatase activities in Alfisol.