Influence of Various Intercropping Ratios on Arsenic Absorption and Remediation Efficiency in Maize/Peanut on Farmland Contaminated by Arsenic

Phytoremediation is a prevalent approach for addressing remediation and production goals in polluted agricultural land. In this study, we examined the impact of four distinct planting ratios on crop growth, accumulation of arsenic (As), and rhizosphere soil dynamics of peanut and maize. The results revealed that intercropping significantly reduced grain As accumulation (42.11–63.16% in maize; 62.28% in peanut under the 1:2 ratio, T2), achieving compliance with Chinese food safety standards (GB 2762-2017, 0.05 mg kg−1). Meanwhile, the T2 treatment exhibited a significantly higher As bioconcentration factor (BCF) and the lowest translocation factor (TF). The metal removal equivalent ratio (MRER) under different planting systems was 1.09, 2.41, 1.07, and 1.46. Additionally, while intercropping did not increase grain biomass per plant, the LER values > 1 for T1 (1.88) and T2 (1.25) demonstrated that complementary resource use enhanced total productivity. Intercropping treatments significantly affected soil properties in both maize and peanut rhizospheres. For maize, intercropping lowered soil pH and available As content but increased dissolved organic carbon (DOC). Notably, only the T1 treatment significantly reduced the cation exchange capacity (CEC) of maize soil. Peanut’s rhizosphere experienced increases in both pH and CEC due to intercropping, with only the T2 treatment yielding a slight rise in DOC. The findings suggest that the maize–peanut intercropping system, especially the T2 system, effectively alters the soil–plant interface to limit As uptake while maintaining productivity, demonstrating its promise for safe utilization of As-contaminated land.