Purpose To explore the effect of incorporating corn straw and applying different alkaline passivators on the risk of cadmium (Cd) contamination in agricultural soils and the reduction of Cd content in vegetables, providing a reference for the safe utilization of Cd-contaminated agricultural soils.
Methods A pot experiment was conducted to investigate the effects of corn straw combined with different passivators (biochar, silicon fertilizer, and calcium-magnesium phosphate fertilizer) on the yield, root morphology, photosynthesis, and Cd accumulation of mini Chinese cabbage.
Results Compared with the control group, applying corn straw alone significantly increased the yield, root length, root volume, stomatal conductance, and transpiration rate of mini Chinese cabbage, with increases ranging from 15.62% to 88.65%; however, it reduced biomass of underground part, root-to-shoot ratio, leaf area, and branches number, with reductions ranging from 21.83% to 42.14%; and no significant effect was observed on the available Cd of soil and Cd content of mini Chinese cabbage. Compared with applying corn straw alone, the addition of passivators significantly increased the yield and biomass of mini Chinese cabbage, with increases ranging from 4.43% to 101.19%; among the treatments, the combination of corn straw and calcium-magnesium phosphate fertilizer was most beneficial in improving mini Chinese cabbage’s root indicators and above-ground biomass, with increases of 13.18%-79.85% and 38.65%-64.29%, respectively; the combination of corn straw and biochar had the most significant positive effect on mini Chinese cabbage’s photosynthesis, with an increase of 13.18%-240.69%. Compared with applying corn straw alone, the combination of biochar, silicon fertilizer, and calcium-magnesium phosphate fertilizer effectively reduced the soil’s available Cd content by 21.02%, 24.40%, and 32.31%, respectively. Additionally, these passivators reduced Cd content in vegetables to varying degrees, with biochar achieving the best reduction in above-ground Cd content (24.94%), while silicon fertilizer was most effective in reducing the above-ground Cd accumulation (14.92%) and underground Cd content (18.77%).
Conclusion The application of corn straw combined with passivators significantly promotes mini Chinese cabbage growth and effectively reduces Cd content in both soil and plants. To enhance crop safety in agricultural production, it is recommended to first apply calcium-magnesium phosphate fertilizer to promote crop growth and reduce soil Cd content, followed by the application of silicon fertilizer or biochar to reduce crop Cd accumulation and absorption, thereby providing an effective technical approach for safe crop production.
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