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Effects Of Different Restoration Measures On The Soil Structure?Organic Carbon And Nitrogen Characteristics In Desert Steppe Ecosystem

Posted on:2020-08-06Degree:MasterType:Thesis
Country:ChinaCandidate:S YuFull Text:PDF
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To understanding the soil structure and the characteristics of carbon and nitrogen of desert steppes with different restoration measures,we selected the desert steppes of deep tillage+reseed(S),shallow ploughing+reseed(Q),no-till+reseed(M),fenceing(F)4 and traditional grazing(CK)as the research object.The soil aggregate composition,soil organic carbon and total nitrogen in the soil profile and distribution of different particle size of aggregate,the changes of organic carbon and nitrogen components at 0-40 cm depth were studied.The influences of different restoration measures on soil structure and carbon and nitrogen characteristic in desert steppe were analyzed.The main conclusions are as follows:(1)The mechanical stability and water stability aggregates of 0-40cm soil layer under different treatments were all microaggregates of<0.25mm as the dominant particle size,and the water stability of large aggregates content(WR0.25)was significantly lower than that of the mechanical stability of large aggregates content(DRO 25).The dry sieve DR0 25,MWD,GMD of 0-40cm soil layer and WR0 25 of 10-30cm soil layer were the highest in shallow tillage grassland.With the deepening of soil layer,the contents of<0.25mm micro aggregates of the mechanical stability and water stability of the grasslands under different treatments decreased,and the soil structure tended to be stable.(2)The soil organic carbon content at the 0-30 cm soil layer and the total nitrogen content at the 0-20cm soil layer were the highest in the shallow ploughing grassland with 9.93-14.90 g/kg and 0.17-0.22 g/kg respectively.The soil carbon and nitrogen reserves at 0-40cm depth were the highest in ploughing grassland(47.72 and].09 t/hm2,respectively).(3)The organic carbon content of the aggregates at the 0-10cm soil layer was the highest in the grazing grassland,and the variation range was 0.99-2.41 g/kg.At the 10-40cm soil layer,they were the highest in shallow ploughing grassland,followed by deep tillage and no-tillage grassland,and fencing and grazing grassland were lower.The total nitrogen contents of the aggregates changed irregularly at the 0-40cm soil layer.The soil aggregates of<0.05mm contributed the most to the total organic carbon and total nitrogen at the 0-40cm soil layer of the grassland under each treatment.(4)In the 0-40cm soil layer,the soil particle organic carbon content was lower in the tilled grasslands,and higher in the no-tillage,fencing and grazing grasslands.The contents of easily oxidized and the water soluble organic carbon at 0-20cm soil layer were higher in no-tillage grassland.The carbon contents of microbial biomass was the highest in the fencing grassland at the 0-30cm soil layer.(5)At the 0-40cm soil layer,the microbial biomass nitrogen was the highest in the shallow-ploughing grassland and the lowest in the grazing grassland,the variation range was 73,19-47.57mh/kg.The nitrate and ammonium nitrogen contents were the highest in grazing grassland and the lowest in fencing grassland.The content of alkali-hydrolyzed nitrogen was the highest in deep ploughed grassland.In this study,shallow ploughing with reseeding can promote the formation of soil aggregates and enhance their stability.Compared with no-tillage,deep tillage and fencing,shallow ploughing was more beneficial to soil carbon and nitrogen accumulation in desert steppe.
Keywords/Search Tags:desert steppe, restoration measures, aggregate stability, organic carbon, total nitrogen, carbon and nitrogen components
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