Oxalic-Acid-treated Waste Mica, a Potent Natural Supplement to K Fertilizers for Growing Wheat and Rice in Inceptisol

Purpose Status of soil health and soil K fertility are degrading due to crop grower’s negligence to K application for growing crops and high cost of K fertilizer. Utilization of non-conventional, low cost K sources can reduce these problems. Method In this study, 0.5 M oxalic-acid-treated waste mica (WM) was used to supplement conventional K fertilizer in incubation as well as pot experiments in Inceptisol. Result Under incubation experiment, oxalic-acid-treated WM (WM (OA)120 ) significantly increased plant available K over control (K 0 ) and untreated WM treatments (WM 120 ). During pot experiment, KCl + oxalic-acid-treated WM treatment (K 30 + WM (OA)60 ) maintained significantly higher water soluble K (WSK), plant available K, and non-exchangeable K (NE-K) over control (K 0 ) and untreated WM (WM 120 ) treatments at different growth stages of wheat. Those consequently increased wheat yield and K uptake under K 30 + WM (OA)60 treatment. The K 30 + WM (OA)60 and KCl (K 60 ) treatments recorded at par wheat yield and K uptake. After growing wheat, K 30 + WM (OA)60 treatment maintained positive soil K balance, whereas K 60 treatment produced negative K balance. As a result, K 30 + WM (OA)60 treatment exerted better residual effect and produced significantly higher rice yield and K uptake as compared to K 60 treatment. In K 30 + WM (OA)60 treatment, oxalic-acid-treated WM successfully supplemented 50% conventional K fertilizers without hampering crop yield and K uptake and improved soil K status. After rice also, the K 30 + WM (OA)60 treatment maintained better WSK, plant available K and NE-K over K 60 treatment. Conclusion Thus, it can be inferred that KCl + oxalic-acid-treated WM treatment can supplement 50% of the K fertilizer without adversely affecting wheat and rice yields and K uptakes, maintain soil K balance, and improve the status of plant available K, WSK, and NE-K.