典型厚层黑土区农地土壤胞外酶季节变化对土壤侵蚀强度的响应OA

[Objective]Studying the responses of seasonal variations in soil extracellular enzymes to soil erosion intensity on farmland in the black soil region can deepen the understanding of the mechanisms by which farmland soil erosion affects soil ecological functions and provides a scientific basis for the sustainable utilization of soil resources.[Methods]Slope farmland in the typical black soil region of Keshan County,Heilongjiang Province was selected.The 137Cs tracing method was used to estimate soil erosion rate,and soil nutrients,microbial biomass,and soil enzyme activities under different erosion intensity grades were measured under natural conditions in summer(June 2023)and autumn(September 2023).The responses of seasonal variations in soil extracellular enzymes to soil erosion intensity on farmland in the typical black soil region of northeast China were analyzed.[Results]1)Soil erosion rates on the farmland slope based on 137Cs tracing ranged from 479.3 t/(km²·a)to 8 041.2 t/(km²·a).The soil erosion intensity grades were primarily classified as slight,moderate,and severe erosion levels.2)Spatial differences in soil extracellular enzyme activities were observed on the farmland slope during summer and autumn.Compared to summer,the activities of soil β-1,4-glucosidase(BG),β-1,4-N-acetylglucosaminidase(NAG),and leucine aminopeptidase(LAP)increased to different degrees across different slope positions in autumn.The spatial distribution of soil extracellular enzyme activities on the farmland slopes was influenced by both soil erosion intensity grades and seasonal variations.3)The response of soil enzyme activities to seasonal variations was most sensitive in the severe erosion zone.In autumn,soil BG and NAG enzyme activities in the severe erosion zone increased significantly by 18.0%and 24.0%,respectively,compared with summer,while LAP and acid phosphatase(ACP)enzyme activities responded relatively weakly to seasonal variations.4)The contents of soil organic carbon(SOC),total phosphorus(TP),water-soluble organic carbon(DOC),and water-soluble nitrogen(DON)were the key factors affecting soil extracellular enzyme activities.[Conclusion]Soil extracellular enzyme activities on the farmland slopes exhibit significant seasonal variations,and the response of these activities to seasonal variations is most pronounced in the severe erosion zone.These findings are of great importance for deepening the understanding of the mechanisms by which farmland soil erosion affects soil ecosystem functions in the black soil region of Northeast China.