Abstract: The aim of this study is to analyze the feasibility of combined application of biochar and nitrogen fertilizer in wheat field from the perspective of functional diversity of soil microbial community. We examined the effects of factorial application of biochar and nitrogen fertilizer on the metabolic characteristics of soil microbial community in wheat field. There were two levels of biochar addition at 0 and 30 t·hm^-2  (B), and three levels of nitrogen addition at 0, 150 (N₁), and 300 kg·hm^-2 (N₂), resulting in six treatments (B, N₁, N₂, BN₁, BN₂ and control (CK)). The BiologECO method was used to assess the metabolism characteristics of soil microbial communities on six carbon sources, including carbohydrates, amino acids, alcohols, esters, carboxylic acids, and amines. Results showed that the metabolic activity of soil microorganisms in different treatments was altered, with a trend of N₁>N₂>B>BN₁>BN₂>CK. The metabolic preferences of soil microbial communities on carbohydrates and alcohols were changed significantly when applied with nitrogen (N₁, N₂) or with lower nitrogen level combined with biochar (BN₁). Soil microbial community richness and evenness were increased by different fertilization treatments. The results of principal component analysis showed that carbohydrates, amino acids, and carboxylic acids were the main carbon sources inducing the differences in metabolism characteristics of soil microbial community under different fertilization regimes. Therefore, the combined application of low nitrogen with biochar (BN₁) was an effective measure to enhance soil microbial community functional diversity and wheat yield.

Key words: biochar, wheat field soil, soil microbial community, Biolog-ECO, metabolism.