Responses of bacterial and fungal community to long-term nitrogen application in Loess Plateau
[Objectives]The community variation of bacteria and fungi are crucial factors deciding soil ecological functions.We studied the response of bacterial and fungal communities and their functional roles to long-term nitrogen application levels in Loess Plateau,China.[Methods]The soil samples were collected in 2022 from the five N application treatment plots of a long-term experiment,which was in the State Key Agro-Ecological Experimental Station in Changwu County,established in 1984.The N application rates in the five selected treatments were 0,45,90,135,and 180 kg/hm2(denoted as N0,N45,N90,N135,and N180).The bacterial and fungal community structures,soil enzyme activities related to carbon cycling,and soil properties were determined,and the changes relative to the initial of experiment were calculated.[Results]N application led to significant changes in soil chemical properties and microbial population and community structures.Compared to the initials,long term N application increased soil microbial biomass carbon from 113.0 to 177.5-234.0 mg/kg,microbial activity from 4.92 to 5.83-7.26 g/(m2·s),and plant root biomass from 1.73 to 2.32-2.98 t/hm2,decreased bacterial community richness and diversity index(Chao1 and Shannon)by 4.0%-12.3%and 1.6%-1.8%,respectively,did not changed fungal communities obviously.N application significantly decreased the relative abundance of Proteobacteria,Gemmatimonadetes,Bacteroidetes,Dothideomycetes,and Agaricomycetes by 2.4%-16.4%,2.1%-26.3%,24.1%-50.0%,29.4%-58.8%,and 44.4%-88.9%,respectively,but increased the relative abundance of Actinobacteria,Acidobacteria,Chloroflexi,Ascomycota,and Tremellomycetes by 10.4%-34.7%,37.8%-54.1%,14.3%-28.6%,8.3%-73.8%,and 18.2%-45.5%.N application elevated soil organic C(SOC)from initial 6.50 g/kg to 7.00-7.35 g/kg,dissolved organic C(DOC)from 22.43 mg/kg to 27.60-34.87 mg/kg,NO3--N from 1.38 mg/kg to 1.78-2.25 mg/kg,and decreased C/N from 8.90 to 8.64-7.74.With the increase of N application rate,the soil nitrification increased by 14.3%to 39.6%,aerobic ammonia oxidation functions increased by 25.1%-48.2%,and the activities of xylanase increased by 13.5%to 39.3%,and that of cellobiose hydrolase increased by 50.3%to 126.8%.The changes of soil bacterial richness and diversity were correlated with that of SOC,DOC,NO3--N,and C/N ratios.The Proteobacteria abundance was negatively linked to DOC levels,Actinobacteria abundance was positively associated with SOC,DOC,and NO3--N contents,Ascomycota and Basidiomycota abundances were not significantly correlated with soil physiochemical properties.[Conclusions]In Loess Plateau,bacteria structures are more sensitive than fungal structure to N application rate.The changes of bacterial community composition are positively correlated with soil organic matter,dissolved organic carbon and NO3--N,and negatively correlated with total nitrogen and C/N.Nitrogen application increased the abundance of functional bacteria related to carbon cycle in soil and promoted the secretion of xylosidase and cellobiohydrolase.
nitrogen application ratetotal nitrogenC/Nenzymatic activitymicrobial community structure
万方数据
维普
