Crop rotation and green manure type enhance organic carbon fractions and reduce soil arsenic content

Abstract

Green manure incorporation has recently emerged as a promising strategy for mitigating heavy metals (HMs) contamination and enhancing soil quality. However, there are still many uncertainties regarding the effects of crop rotation and the type of incorporated green manure on soil organic carbon fractions and arsenic (As) mitigation in As-contaminated soil. Thus, a two-phase experiment was conducted to determine the effects of crop rotation and green manure type on the distribution of organic carbon fractions and As accumulation in soil and brown rice plants. It was found that green manure incorporation increases soil nutrient content with an increase in total carbon of 18.64 %, 18.10 %, and 19.83 % under BC-R, AS-R, and LP-R respectively, and enhances organic carbon fractions. Furthermore, soil As concentration was significantly decreased by green manure incorporation for 20.65 %, 20.02 % and 19.99 % under BC-R, AS-R and LP-R respectively while As concentration in brown rice various parts was under permissible limits. This study highlights the complex interactions between green manure-brown rice rotation and green manure incorporation on soil organic carbon fractions, and As content in soil and brown rice, and emphasizes further research to elucidate optimal cultivation strategies of continuous crop rotation and green manure incorporation for sustainable remediation of As-contaminated soils while ensuring food safety.