Research On The Effect Of No-till Straw Return On Degradation Of Arable Ecosystems And Loss Of Soil Nitrate Nitrogen Leaching

Due to long-term cultivation and intensive farming and the removal of above-ground biomass,the organic matter content of the originally fertile black soil has been declining for years,and the number of soil microorganisms and their secreted extracellular enzyme activities have significantly decreased.Therefore,this study takes conservation tillage as the core technology for the restoration of arable soil ecosystems in the Northeast black soil region.In order to investigate the effects of no-till straw return on arable ecosystems and soil nitrate nitrogen content in black soil areas,this study was conducted in Lishu County,Jilin Province.Three treatments Conventional tillage(CT),No-till+no-straw return(NT-0)and No-till+total-straw return(NT-100))were selected to determine the changes in soil organic carbon,total nitrogen,microbial communities and soil enzyme activities in 0-5 cm,5-10 cm and 10-20 cm soil layers under different tillage modes and loss of nitrate nitrogen from20-40 cm and 40-60 cm soil layers.The results show that no-till straw return to the soil significantly affects the soil total nutrient content,microbial biomass,structure and enzyme activities and their distribution among soil layers.Soil organic carbon,total nitrogen and water-soluble carbon contents,bacterial,fungal and actinomycete microbial biomass and β-glucosidase,fibrous disaccharidase and β-N-acetylamino glucosidase activities were significantly higher in the soil than in the CT and NT-0 treatments.Soil nitrate nitrogen accumulated in the surface layer in all three treatments,but it was not lost to the lower layer in the no-till straw return treatment.The straw returned to the field promoted the microbial turnover and accumulation of soil organic carbon,and the longterm no-till improved the stability of soil organic matter.No-till,especially no-till straw fallowing,is an effective way to improve the stability of arable ecosystems in black soil areas and to mitigate the effects of soil nitrate nitrogen leaching.