Enhancing remediation efficiency of cadmium-contaminated soil: integrating forage-microorganism systems with agronomic strategies.

Abstract

Soil contamination due to heavy metals, especially cadmium (Cd), poses a growing concern. This study seeks to develop an economical and non-polluting sustainable remediation program for Cd-contaminated soil to address this issue. This study pioneered the exploration of Cd accumulation patterns in three forage species: Lolium multiflorum Lamk (LMJS), Sorghum bicolor × sudanense (SSBJ), and Sorghum sudanense (Piper) Stapf (SUJS) to identify their optimal harvest periods in Cd-contaminated soils. Additionally, a consortium of beneficial microorganisms (combinations of C, F, and H; C: 10% Bacillus subtilis; F: 20% Bacillus subtilis + 10% Bacillus cereus + 20% Citrobacter; H: 20% Deinococcus radiodurans + 10% Bacillus cereus) was implemented, with a focus on developing an efficient forage-microbial co-remediation system. Subsequently, agronomic strategies (mowing or chelating agents) were employed to improve the Cd enrichment capacity of the combined forage-microbe remediation system, offering sustainable field remediation strategies. The results indicate that the SSBJ + F combined remediation system was mowed on the 60th day (stubble left at 35 cm, light mowing) and harvested on the 120th day as the optimal choice. The bioaccumulation quantity (BCQ) unit accumulation in Cd-contaminated soil at a concentration of 10 mg/kg reached 0.397 mg/kg, and the annual Cd removal rate was 9.23%, representing a 29.63% increase compared to the control group. The results of this study provide valuable insights into the development of practical, field-applicable remedial measures for cadmium-contaminated soils while minimizing environmental impacts.