Oxalic acid treated low grade rock phosphate can be a potent supplemental P source to grow wheat in inceptisol

High grade rock phosphates (HGRP) are only used to prepare phosphorus (P) fertilizers. But the finite reserve of HGRP is pushing the agricultural sectors to use low grade rock phosphates (LGRP) for growing crops. In this study an attempt was made to treat LGRP with oxalic acid and use it as a supplement to P fertilizer for growing wheat in Inceptisol. Incubation study revealed that oxalic acid treated rock phosphate (RP) can significantly increase soil available P status as compared to inert untreated RP treatment. Pot study established that oxalic acid treated RP (@60 mg P2O5 kg−1) under DAP30+ RP60(OA) treatment has supplemented 50% P fertilizer without affecting wheat yields and P uptake. DAP30+ RP60(OA) treatment also had maintained significantly higher Saloid-P, organic-P and statistically at par available P, dehydrogenase, acid phosphatase and alkaline phosphatase activities as compared to chemical fertilizer treatment (DAP60). Thus it can be inferred that, application of oxalic acid treated LGRP (@ 60 mg P2O5 kg−1) can supplement 50% of the P fertilizer demand to grow wheat in Inceptisol.

高品位磷矿（High grade rock phosphates, HGRP）仅用于制备磷肥。但受限于高品位磷矿的有限储量，农业生产领域正逐步转向使用低品位磷矿（Low grade rock phosphates, LGRP）开展作物种植。本研究尝试采用草酸对低品位磷矿进行处理，并将其作为磷肥补充剂，在始成土（Inceptisol）中开展小麦种植试验。培养试验结果表明，与未处理的惰性磷矿（rock phosphate, RP）处理组相比，经草酸处理的磷矿可显著提升土壤有效磷含量。盆栽试验证实，在DAP30+RP60(OA)处理模式下，以60 mg P₂O₅·kg⁻¹的用量施用草酸处理磷矿，可在不影响小麦产量与磷素吸收的前提下，替代50%的常规磷肥用量。与纯化肥处理组（DAP60）相比，DAP30+RP60(OA)处理组还可维持更高的盐溶态磷（Saloid-P）与有机磷（organic-P）含量，且其有效磷含量、脱氢酶、酸性磷酸酶及碱性磷酸酶活性与纯化肥组统计学上无显著差异。由此可见，在始成土中以60 mg P₂O₅·kg⁻¹的用量施用草酸处理低品位磷矿，可满足小麦种植中50%的磷肥需求。