Can soil remediation agents synergistically mitigate rice Cd content and CH4 emission from karst paddies?

Rice ( Oryza sativa L.) paddies are increasingly threatened by cadmium (Cd) pollution, and potentially serve as CH 4 emitters to the atmosphere. Remediation agents widely mitigate Cd pollution in paddy soil, however, we know little about their regulations on CH 4 emission. Here, via adding biochar (B), sulfhydryl-modified palygorskite (SMP), and selenium foliar fertilizer (SFF), we conducted a pot experiment to investigate soil and rice Cd contents together with in - situ CH 4 fluxes. Compared to CK, the addition of SMP, SFF, and B-SMP reduced Cd in brown rice by 25% to 50%, 25%, and 50% to 75%, respectively. Agents 7% B, 7% B-0.01% SMP, and SFF reduced CH 4 emissions by 8.46%, 5.30%, and 4.11%, respectively. CH 4 emission increased gradually along the growing season, with the cumulative CH 4 fluxes ranging between 338.82 and 619.13 kg hm −2 . Our results highlight that mixed 7% B-0.01% SMP and SFF showed collaborative effects on Cd remediation and CH 4 emission. This study reveals the feasibility of reducing Cd pollution and CH 4 emission in karst rice paddies, which hopes to supplement the knowledge of collaborative controls on soil remediation and carbon emission.