Potential implications of biochar and compost on the stoichiometry-based assessments of soil enzyme activity in heavy metal-polluted soils

Biochar and compost application in soil has been proved as an environmental management and soil remediation strategy for upgrading soil quality and growth-promoting soil microorganisms. A detailed examination of the fluctuations and stoichiometric interactions between β-glucosidase (BG), N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (AP) after applying biochar and compost to the heavy metal soils was conducted in the paper. However, biochar stimulated the activity of AP and inhibited BG, NAG, and LAP. Compost and biochar-compost might strengthen BG, NAG, LAP, and AP activities. Redundancy analysis discovered that the crucial parameters that affected soil enzyme activity were TN, NO3−-N, and TP. However, the stoichiometric ratio of C/N, C/P, and N/P with the application of the biochar, compost, and biochar-compost could be changed. While alleviating the P-limitation in soils under Cu stress, biochar may also alleviate the C-limitation in soils under As, Cd, and Zn stress. Compost and biochar-compost application alleviated C-limitation in heavy-metal (Cu, As, Cd, and Zn) polluted soil. This work will help us further understand the stoichiometry and energy restrictions of biochar and compost on ecological functional enzymes.