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Silicon-rich agro-industrial wastes for sustainable management of iron toxicity and acidity of lateritic rice wetlands #MMPMID41359115
Parambat K; Nair MMR; Nair SS
Environ Sci Pollut Res Int 2025[Dec]; ? (?): ? PMID41359115show ga
Utilization of agro-industrial wastes as soil amendment manages acidity, remediates heavy metals, and ensures environmental sustainability. The present study aims to test non-conventional organic Si sources, milled rice husk char (T(MRHC)), and powdered diatomaceous earth (T(DE)) against burnt lime (T(BL)) and calcium silicate (T(CS)) for amending iron (Fe) toxicity and acidity at tillering (TI), panicle initiation (PI), and harvest (HA) of a short duration rice variety Manuratna in lateritic rice wetlands of Kerala. Irrespective of the growth stages of rice, T(MRHC) recorded the lowest water-soluble Fe (WS-Fe), acid-soluble Fe (AS-Fe), manganese oxide (MnO)-occluded Fe (MN-Fe), and residual Fe (RS-Fe) fraction in soil. WS-Fe indirectly enhanced Fe adsorption into specifically adsorbed lead displaceable Fe (SP-Fe) and AS-Fe, whereas AS-Fe abridged the Fe adsorption between WS-Fe and MN-Fe > OM-Fe. Organic Si sources recorded a strong negative influence on organic matter-occluded Fe (OM-Fe) (standardized path coefficient p = - 0.94), amorphous iron oxide (FeO)-occluded Fe (AM-Fe) (p = - 0.74), and crystalline FeO-occluded Fe (CR-Fe) (p = - 0.53) content in soil. Fractions of Fe and forms of acidity were significantly (p = 0.05) and positively correlated. T(BL) maintained the highest soil pH at all the critical growth stages (5.90(TI), 6.04(PI), and 5.99(HA)) of rice, which was statistically on par with T(MRHC) (5.90(TI), 6.02(PI), and 5.96(HA)). The highest reduction of Fe in rice was recorded with T(BL) at TI (16%) and PI (18.76%), while at HI (21%), T(MRHC) was found to the most effective. T(BL) and T(MRHC) were statistically on par in reducing WS-Fe (at PI and HA), exchangeable acidity and extractable acidity (at TI), and total acidity (at HI). The grain yield of Manuratna rice was found to vary in the order T(CS) > T(MRHC) and T(BL).