Prior film mulching alters cadmium dynamics at the soil–plant interface in successive crops: enhancing phytoremediation and ensuring safe production

Film mulching (FM) is widely applied in modern agriculture; however, its residual effects on cadmium (Cd) accumulation in subsequent crops and soil Cd bioavailability within rotation systems remain poorly understood. This study investigated three rotation systems, Oil sunflower-Rape, Soybean-Flax and Sedum alfredii-Peanut, to evaluate the influence of FM in previous crops on the phytoremediation potential of subsequent crops. Compared to the non-film mulched (NFM) treatments, previous crop FM significantly increased biomass by 28.4% in rape and 21.1% in flax, accompanied by higher Cd concentrations, resulting in 18.9-137.2% and 5.1-40.2% greater Cd accumulation, respectively. In contrast, FM reduced peanut biomass by 4.7% and Cd accumulation by 22.4-38.2%. FM decreased soil pH and organic matter (OM) content, while increasing available Cd by 7.1-42.9%, thereby promoting Cd uptake in most systems. Consequently, Cd remediation efficiency increased by 105% in rape and 70.4% in flax but decreased by 36.1% in peanut. Overall, previous crop FM enhanced Cd remediation efficiency in double oilseed-crop systems, but reduced Cd accumulation and remediation efficiency in the Sedum alfredii-Peanut system. These findings provide practical guidance for optimizing Cd-contaminated farmland remediation strategies and ensuring the safe production of oilseed crops.