Interactive effects of soil moisture and temperature on chromium-induced microbial and enzymatic stress

Climatic conditions play a critical role in soil health, as changes in temperature and moisture directly impact soil microbial populations. The presence of potentially toxic elements, particularly chromium (Cr), poses a significant threat to microbial communities and can alter soil chemical properties. Current study investigated the effects of Cr toxicity under varying soil volumetric water contents (30% and 40%) and temperature (25 °C and 40 °C) on microbial biomass and enzyme activities. The experiment was conducted over 60 days with six Cr levels: control, 50, 100, 150, 200, and 250 mg Cr kg^-1 soil. Results revealed a significant reduction in soil microbial biomass carbon, nitrogen, phosphorus, and sulfur at Cr contamination levels above 100 mg kg^-1. Specifically, at 30% soil moisture and 25 °C, microbial biomass carbon, nitrogen, phosphorus, and sulfur were reduced by 59.09, 66.72, 50.82, and 61.03%, respectively. At 40% soil moisture and 40 °C, reductions were recorded 23.77, 46.95, 48.83, and 30.87%, respectively. Additionally, soil enzyme activities declined with increasing Cr levels. Amidase, urease, alkaline phosphatase, β-glucosidase, arylsulfatase, and dehydrogenase activities decreased to 47.98, 50.41, 50.32, 64.34, 46.64, and 48.49% at 30% soil moisture and 25 °C, respectively. At 40% soil moisture and 40 °C, reductions were calculated 32.90, 37.09, 45.39, 55.71, 38.37, and 36.76%, respectively. The findings indicate that chromium contamination and changes in soil moisture and temperature significantly compromise soil microbial biomass and enzyme activities. This study highlights the need for monitoring and mitigating Cr contamination to maintain soil biological health and overall ecosystem functionality.