Effects of straw and roots removal on soil Cd availability and Cd accumulation in rice at different growth stages

It is argument on whether straw removal present a safer alternative compared to straw return or not where in paddy fields contaminated with cadmium (Cd). The objective of this study was to evaluate the impacts of varying levels of straw and roots removal on Cd uptake and accumulation, as well as on the growth of rice, Cd availability of soil at different growth stages, and the safety and nutritional value of brown rice were subject to assessment as well. A field experiment was conducted wherein rice straw and roots were returned into the paddy field, serving as the control group (CK). The findings revealed that the removal of straw and roots resulted in a decline in the availability of Cd in soil and the accumulation and uptake of Cd by rice plant. At the maturation stage of rice, the soil available Cd content and brown rice Cd content was significantly reduced by 40.39% and24.79 % under the treatment where 100 % of rice straw and roots were removed. Moreover, there was a significant decline of 66.54 % and 76.35 % in dissolved organic carbon (DOC) and Cd concentrations respectively within soil pore water. This suggests that one crucial factor contributing to decreased Cd accumulation is the diminished complexation between DOC and Cd resulting from straw removal treatments. The removal of straw and roots had minimal impact on the nutritional components of brown rice, including essential amino acids. After the removal of straw and roots from the field, there was a reduction in hazard quotient (HQ) for rice consumers of varying genders and ages in the region by 17.71–24.95 %, leading to a decrease in local ecological risk level from medium to slight. Therefore, the implementation of strategies such as removing straw and roots could potentially lead to successful outcomes in reducing rice Cd uptake in paddy fields contaminated with this metallic element.