| Based on a long-term location nutrient cycling experiment on oasis farmland soil in Fukang Station of Chinese Academy of Sciences, Fukang, Xinjiang, China, the thesis is designed to investigate the effect of long-term fertilization on the evolution of farmland soil carbon pool and spatial distribution characteristics of water stability of aggregates in the arid area of oasis. The no-fertilization treatment (CK), chemical fertilizers treatment alone(NPK), chemical fertilizer plus organic manure treatment (NPKM) and chemical fertilizer plus straw (NPKS) were used to explore the soil inorganic carbon (SIC) and organic carbon (SOC)variation in the content and storage of the soil profile and the fertilization years. The activated carbon fractions content and water stability of aggregates in the spatial distribution of long-term fertilization were analyzed. The main results were as follows:(1) The impact of SOC and SIC content in fertilization treatment, soil depth and fertilizer time were a significant difference (P<0.01)(P<0.01). Long-term fertilizer application(NPK, NPKM and NPKS)had significantly higher SOC and SIC content (P<0.05), which compared with no fertilizer application treatment(CK), SIC was increased by6.9%,9.5%and11.4%, respectively, and SOC was increased by1.52%,2.08%å'Œ1.95%. In different soil depths, SIC average content for fertilization treatments from9.11g·kg-1in the0～20cm depth increased to9.96g·kg-1in the40～60cm depth, on contrast, the SOC average content from4.95g·kg-1in the0～20cm depth reduced to2.32g·kg-1in the40～60cm depeh. The SIC content first decreased and then stabilized with the fertilization of years in the depth of 0-60cm, and the SOC content increased significantly with the fertilization of years.(2) Long-term fertilizer application had a significant influence on farmland SIC and SOC stocks, but the same fertilizer treatments had no significant influence on SIC stocks in different fertilization times. On contrast, that had a significant influence on SOC stocks, various fertilizer treatments except CK had significantly higher SOC stocks with the fertilization of years increases. The soil carbon storage (SIC and SOC) and grain yield showed significant positive linear correlation.(3) After long-term applying fertilizers, the active carbon fraction in surface layer (0-20cm) content and stocks are significantly higher than the bottom (20-60cm), the surface particles of carbon stocks was about80%, which show the proportion of surface particulate carbon stocks on the whole profile-level particulate carbon storage plaied a leading role, while the surface of soluble organic carbon and dissolved inorganic carbon stock changed in whole soil profiles.In each fertilization treatment, long-term fertilizer application had a significant influence on the surface of the active carbon fractions content stocks, especially combined application of organic and inorganic fertilizers was significantly higher than other fertilization treatments. The underlying, long-term fertilizer application had a significant influence on light fraction carbon and dissolved inorganic carbon content, and combined application of organic and inorganic fertilizers significantly higher than other treatments.(4) Micro-aggregates (<0.25mm) was improved that be in the whole profile level as the dominant particle size of arid oasis farmland water-stable aggregates fractions, long-term fertilization conducive to the formation of aggregates. Especially combined application of organic and inorganic fertilization treatment can significantly increase surface water-stable macro-aggregates (>2mm and0.25-2mm) content, no significant effect on the level of micro-aggregates in each section.(5) Long-term application fertilizer can increase all levels of organic carbon content of the aggregates, in particular organic and inorganic fertilizer significantly increased water-stable aggregates (0.25-2mm) organic carbon content. The results indicated that long-term organic inorganic fertilizers increase the water-stable macro-aggregates organic carbon sequestration.(6) A combined application of organic and inorganic fertilizers significant increased the content of water-stable aggregates, its stability and soil total organic carbon in the active component significantly correlated. |
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