The Effect of Biochar Addition in Potato Fields on Microbial Communities in the Arid Region of Northern China

Biochar is an effective soil amendment for improving soil function; however, the effects of biochar produced at different pyrolysis temperatures on soil microbial community structure and enzyme activities remain insufficiently studied. A field experiment was conducted from 2023 to 2024 in the arid and semi-arid region of Northern China to investigate the effects of biochar produced at different pyrolysis temperatures (T1: 300 °C; T2: 500 °C; T3: 700 °C) and application rates (C1: 10 t ha−1; C2: 20 t ha−1; C3: 30 t ha−1) on soil chemical properties, microbial community structure, enzyme activity, and potato nutrient use efficiency. The results indicated that the C2T2 treatment was most effective in enhancing soil fungal and actinomycete populations, increasing total microbial biomass, significantly improving soil enzyme activities, and ultimately promoting crop yield. Structural equation modeling indicated that biochar regulates soil nutrient supply, drives microbial community succession toward functional specialization, prolongs microbial regeneration cycles, and ultimately enhances potato nutrient use efficiency. The results of this research provide scientific evidence to support the sustainable development of potato farming in the North China region.