| In order to explore the effect of organic materials returning on the extracellular enzyme activity of albic soil, a two-year positioning experiment was conducted in the albic soil area. Four treatments were set up : conventional control treatment ( CK, no straw and no organic fertilizer addition ), straw returning treatment ( S ), organic fertilizer returning treatment ( M ) and straw with organic fertilizer returning treatment ( SM ).The results showed that the application of organic materials increased the content of soil carbon, nitrogen and phosphorus, but had no significant effect on the stoichiometric ratio of C:N, C:P and N:P content. The application of organic materials significantly increased the activity of soil carbon, nitrogen and phosphorus acquisition enzymes, among which the increase of soil nitrogen acquisition enzyme activity was the most significant, and the effect of organic fertilizer ( M, SM ) returning on soil carbon, nitrogen and phosphorus acquisition enzymes was better than that of straw ( S ) returning. The stoichiometric scatter diagram of extracellular enzymes showed that the soil microbial community was limited by both carbon and phosphorus, and the input of organic materials could alleviate the carbon and phosphorus limitation of the soil microbial community. In addition, based on random forest analysis, it was found that soil available phosphorus, microbial biomass carbon, nitrogen and phosphorus were important factors affecting soil microbial carbon and phosphorus limitation indicators. This study deepened our understanding of the stoichiometric characteristics of extracellular enzymes and the demand of microbial community resources in albic soil after the return of organic materials to the field, and provided new ideas and data support for the improvement of albic soil in Northeast China. |