Arsenic (As) transfer from contaminated soils to food grains is a major pathway of As entry into humans in paddy growing areas posing a serious risk to human health. This study investigates the effectiveness of irrigation water management combined with phosphate (P) and vermicompost applications, in immobilizing As and blocking its entry to rice grain. Different doses (0, 30 and 60 mg kg–1) of P, vermicompost (C), (0, 2.5 and 5.0 g kg–1) were applied under W1 (submerged) and W2 (alternate wetting and drying, AWD). Total and bioavailable As in soil were 33.8 mg kg–1 and 3.41 mg kg–1, respectively. Under different treatment combinations, As in soil was highest in amorphous hydrous oxides of Fe and Al (F3) fraction whereas least in non-specifically sorbed (F1) fraction. Arsenic content in rice grain decreased from 0.38 (P1-0 mg kg–1) to 0.25 mg kg–1 (P3-60 mg kg–1), whereas in case of vermicompost application the grain As decreased from 0.32 (C1-0 g kg–1) to 0.27 mg kg–1 (C3-5.0 g kg–1). The lowest grain As content was observed under the W2 condition with the combined application of P (P2-30 mg kg–1) and vermicompost (C2-2.5 g kg–1). Both grain and straw As were positively correlated with As associated with F1 and F2 soil fractions, whereas both showed negative correlation with As in F3, dithionite citrate bicarbonate-As, and oxalate-extractable Fe. Overall, the combined application of P (at 30 mg kg–1) and vermicompost (at 2.5 g kg–1) effectively reduced grain As content under W2. These findings suggest that combining AWD with P and vermicompost application can be a viable approach for reducing As toxicity in rice cultivation; however, field-scale validation across different soils and cultivars is required before broader recommendations can be made. Graphical Abstract Based on the graphical abstract, this study evaluates the effectiveness of irrigation water management combined with phosphate (P) and vermicompost (C) applications in immobilizing arsenic (As) and limiting its transfer to rice grains. Different doses of P and vermicompost were applied under two irrigation regimes: W1 (continuous submergence) and W2 (alternate wetting and drying, AWD). The total and bioavailable As contents in soil were 33.8 mg kg⁻¹ and 3.41 mg kg⁻¹, respectively. Across all treatment combinations, the highest proportion of soil As was associated with the amorphous hydrous oxides of Fe and Al (F3), while the lowest was found in the non-specifically sorbed (F1) fraction. Under W1 conditions, As distribution was higher in labile fractions (F1 = 0.52% and F2 = 14.8%) and lower in the non-labile F3 fraction (38.1%). In contrast, W2 conditions resulted in greater As accumulation in the non-labile F3 fraction (44.8%) and reduced proportions in labile fractions (F1 = 0.31% and F2 = 12.3%). The lowest As concentration in rice grain was observed under W2 with the combined application of P and vermicompost. Overall, the results indicate that integrating AWD irrigation with P and vermicompost application is a promising strategy for reducing As toxicity in rice cultivation.

Managing Soil–Water–Nutrient Interactions to Limit Arsenic Uptake in Rice: A Pot Study

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发表日期：

2026年5月14日

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Rahul Mishra,
Siba Prasad Datta,
Debasis Golui,
Mahesh Chand Meena,
Bramha Swaroop Dwivedi,
Md. Basit Raza,
Devi Prasad Upadhyay,
Mohammad Mahmudur Rahman,
Sanjib Kumar Behera

摘要

Arsenic (As) transfer from contaminated soils to food grains is a major pathway of As entry into humans in paddy growing areas posing a serious risk to human health. This study investigates the effectiveness of irrigation water management combined with phosphate (P) and vermicompost applications, in immobilizing As and blocking its entry to rice grain. Different doses (0, 30 and 60 mg kg^–1) of P, vermicompost (C), (0, 2.5 and 5.0 g kg^–1) were applied under W₁ (submerged) and W₂ (alternate wetting and drying, AWD). Total and bioavailable As in soil were 33.8 mg kg^–1 and 3.41 mg kg^–1, respectively. Under different treatment combinations, As in soil was highest in amorphous hydrous oxides of Fe and Al (F3) fraction whereas least in non-specifically sorbed (F1) fraction. Arsenic content in rice grain decreased from 0.38 (P₁-0 mg kg^–1) to 0.25 mg kg^–1 (P₃-60 mg kg^–1), whereas in case of vermicompost application the grain As decreased from 0.32 (C₁-0 g kg^–1) to 0.27 mg kg^–1 (C₃-5.0 g kg^–1). The lowest grain As content was observed under the W₂ condition with the combined application of P (P₂-30 mg kg^–1) and vermicompost (C₂-2.5 g kg^–1). Both grain and straw As were positively correlated with As associated with F1 and F2 soil fractions, whereas both showed negative correlation with As in F3, dithionite citrate bicarbonate-As, and oxalate-extractable Fe. Overall, the combined application of P (at 30 mg kg^–1) and vermicompost (at 2.5 g kg^–1) effectively reduced grain As content under W₂. These findings suggest that combining AWD with P and vermicompost application can be a viable approach for reducing As toxicity in rice cultivation; however, field-scale validation across different soils and cultivars is required before broader recommendations can be made.

Graphical Abstract

Based on the graphical abstract, this study evaluates the effectiveness of irrigation water management combined with phosphate (P) and vermicompost (C) applications in immobilizing arsenic (As) and limiting its transfer to rice grains. Different doses of P and vermicompost were applied under two irrigation regimes: W₁ (continuous submergence) and W₂ (alternate wetting and drying, AWD). The total and bioavailable As contents in soil were 33.8 mg kg⁻¹ and 3.41 mg kg⁻¹, respectively. Across all treatment combinations, the highest proportion of soil As was associated with the amorphous hydrous oxides of Fe and Al (F₃), while the lowest was found in the non-specifically sorbed (F₁) fraction. Under W₁ conditions, As distribution was higher in labile fractions (F₁ = 0.52% and F₂ = 14.8%) and lower in the non-labile F₃ fraction (38.1%). In contrast, W₂ conditions resulted in greater As accumulation in the non-labile F₃ fraction (44.8%) and reduced proportions in labile fractions (F₁ = 0.31% and F₂ = 12.3%). The lowest As concentration in rice grain was observed under W₂ with the combined application of P and vermicompost. Overall, the results indicate that integrating AWD irrigation with P and vermicompost application is a promising strategy for reducing As toxicity in rice cultivation.