Abstract:

To explore the safe utilization strategies for Cd and As co-contaminated pepper fields with excessive cadmium content, without modifying existing agricultural practices or compromising soil productivity, this study evaluated the effects of three amendments, namely Vedikang soil conditioner (WDK), Tuchuanbingke microbial agent (TCBK) and Jiangsu Tianxiang microbial agent (JSTX), on heavy metal dynamics in the soil-pepper system. The results showed that (1) WDK, TCBK and JSTX significantly reduced soil Cd content by 0.05-0.09 mg/kg (P<0.05) while increasing soil Cr content by 3.7-14.4 mg/kg (P<0.05). Notably, WDK and JSTX decreased soil As concentrations by 2.7 and 3.9 mg/kg, respectively, whereas TCBK exhibited a marginal As increment of 0.6 mg/kg (P<0.05). The effects of the three materials on the contents of mercury (Hg) and lead (Pb) in the soil were not significant (P>0.05). (2) Although Cd reductions in current-season peppers were statistically insignificant (0.018-0.027 mg/kg, P<0.05), all treatments significantly diminished Cd accumulation in previous-season peppers by 0.068-0.077 mg/kg (P<0.01). No significant alterations in Pb levels were observed across treatments, and Hg, As and Cr remained undetectable in pepper fruits. WDK and JSTX significantly increased the yield of peppers by 32.2% and 15.7%, respectively, while TCBK significantly reduced the yield by 7.8% (P<0.05). In summary, all three treatments, WDK, TCBK and JSTX, were effective in reducing soil Cd content and increasing soil Cr content, but their effects on soil As varied depending on the material, and had no significant impact on soil Hg and Pb. All three treatments could significantly reduce the Cd content of peppers in both current and previous seasons, but had no significant effect on the Pb content of peppers. WDK and JSTX could significantly increase the yield, while TCBK significantly reduced it.

Key words: microbial agents, soil conditioner, heavy metal, dryland, pepper