Effects Of Nutrients Addition On Soil Microbial Community Characteristics Of Leymus Secalinus Grassland In North Shanxi

The nutrients addition will affect the content of soil available nutrient and quality of pant litter,and potentially affect the structure and diversity of soil microorganisms.In this study,the Loess Plateau Grassland Ecosystem Observation and Research Station in Youyu,Shanxi was taken as a research object.In2017,8 treatment were set up in a three-factor random block design(control,nitrogen,phosphorus,potassium,nitrogen and phosphorus,Phosphorus and potassium,nitrogen and potassium,nitrogen,phosphorus and potassium).The addition amount of nitrogen,phosphorus,and potassium were all 10 g m-2yr-1 starting from 2018 each year in the beginning of May.Soil samples were collected in August of 2019 and 2020,and the soil microbial community characteristics were researched by Phospholipid fatty acids(PLFA).The results showed that:1.The addition of nitrogen,phosphorus and potassium alone had no significant effect on soil microbial biomass carbon and nitrogen(P > 0.05).The interaction of phosphorus and potassium significantly increased the soil microbial biomass carbon and microbial biomass nitrogen(P<0.05),while the interaction of nitrogen and phosphorus and nitrogen and potassium interaction the interaction with nitrogen,phosphorus and potassium had no significant effect on soil microbial biomass carbon and nitrogen(P>0.05).2.The addition of nitrogen,phosphorus and potassium alone did not have a significant impact on the characteristics of the soil microbial community(P > 0.05).The interaction of nitrogen and phosphorus significantly increased the PLFA content of soil bacteria,gram-positive bacteria,gram-negative bacteria and mycorrhizal fungi(P<0.05).The interaction of nitrogen and potassium,the interaction of phosphorus and potassium,and the interaction of nitrogen,phosphorus and potassium had no significant effect on the characteristics of soil microbial community(P>0.05).3.Soil microorganisms responded significantly to interannual variability(P < 0.05),but were not sensitive to nutrient addition(P>0.05).The analysis results of the mixed linear model showed that nutrient addition had no significant effect on soil microbial biomass carbon and nitrogen(P>0.05),soil total PLFA,soil bacteria,fungi and actinomycete PLFA;treatment year had no significant effect on soil microbial biomass nitrogen and soil total PLFA(P > 0.05).The influence of the amount of soil bacteria and the amount of soil bacterial PLFA were extremely significant(P<0.01).By constructing a structural equation model,it was found that nutrient addition affects the amount of soil bacterial PLFA by changing the total nitrogen content of the soil(R2=0.13).