| Soil organic carbon is an important index of soil fertility, the effect of stability of fixation and the soil organic carbon reserves. Soil organic carbon stability is determined by soil characteristics and the external environment factors. Nitrogen and carbon elements with two life the most basic elements of ecological system, in the cycle of nature not only make an important contribution to the global warming, and the circulation process were coupled, mutual influence and effect of their own. So the research on the effects of different nitrogen levels on soil organic carbon stability, has important significance in theory and practice.In this paper the farmland wind sand soil and alluvial soil as the research object, using the method of field experiment and indoor analysis combined, in different nitrogen treatments of aeolian sandy soil and alluvial soil total organic carbon, organic carbon, dissolved organic carbon, microbial biomass carbon and humus composition and spectral properties were studied, so as to further to clarify the effects of different nitrogen treatments on Aeolian Sandy Soil and alluvial soil organic carbon stability, formulate effective measures for the control of soil carbon reserves and organic carbon in soil, thereby reducing carbon dioxide emissions, but also provide the technical measures and theoretical basis for actual agricultural production.The results of the study show that: the long-term application of different amount of nitrogen fertilizer had a certain influence on the soil organic carbon increased with the increase of nitrogen fertilizer, the amount of soil total organic carbon, showing a trend of decrease after the first increase, basically the same in the two kinds of soil change trend, slightly different. Among them, in the alluvial soil, when the amount of nitrogen fertilizer was 270kg/hm2, soil organic carbon content was the highest, and the wind sand when the dosage of nitrogen fertilizer was 240 kg/hm2, the soil organic carbon content was the highest; with the nitrogen fertilizer, the content of soil easily oxidized organic carbon increased first and then decreased, alluvial soil in N168 treatment reached the maximum value at 4.54g/kg, sandy soil easily oxidized organic carbon content was the highest in the treatment of up to 3.48g/kg for N240.Different amount of nitrogen fertilizer had a certain influence on the oxidation stability of soil organic carbon. Among the different treatments, soil organic carbon oxidation stability trend is different, among them, the aeolian sandy soil organic carbon oxidation stability coefficient in 0.43 ~ 0.57, N270 oxidation stability coefficient was the highest 0.75, N168 oxidation stability coefficient low of 0.43. In the alluvial soil changes in soil organic carbon oxidation stability coefficient range of 0.29 ~ 0.66 N270, the maximum value is 0.66, the minimum value of 0.29 in N312 treatment, there were significant differences between different treatments(P0.05 < 1). At different nitrogen levels in water soluble organic carbon and microbial biomass carbon are all relatively obvious, in sandy soil and the aeolian sandy soil, all are the maximum value in N240.This shows that the nitrogen level had influence on the activity of soil organic carbon, organic carbon activity in a certain range, but with the increasing of nitrogen application amount of organic carbon decreased activity, enhance the oxidation stability of organic carbon, is conducive to soil organic carbon fixation, excessive nitrogen fertilizer can make the stability of soil organic carbon decreased.Different amount of nitrogen fertilizer had a certain influence on the composition and optical properties of soil humus. Hu Minsu(HM) thick humus content in aeolian sandy soil and alluvial soil, with the increase of nitrogen application amount change is not very obvious, but also increased to some extent; humus(HE) in determination of the same trend with HM, was also a small increase; with the increase of nitrogen application amount, Hu Min acid content increased slightly. Aeolian sandy soil and alluvial soil treatment and reached the highest at N240; fulvic acid organic carbon content increased with the increase of nitrogen rate fell, but in the high nitrogen amount appeared to rise, indicating nitrogen corresponding mechanism of fulvic acid content is not significant. Through the infrared spectrum of nitrogen fertilizer on water quality of different analysis shows that in the sandy soil, the amount of nitrogen fertilizer can make the aliphatic compounds and polysaccharides and steroids content increased; while in the alluvial soil nitrogen fertilizer instead of aliphatic compounds and polysaccharides, steroids reduce.Different amount of nitrogen fertilizer had a certain influence on the stability of soil organic carbon. Among the different treatments, the aeolian sandy soil and alluvial soil total soluble N240 treatment group H2SO4 was the highest content was 2.72g/kg, the alluvial soil than sandy soil, soluble group soluble group HCl hydrolysis and H2SO4 hydrolysis to obtain the changes are basically the same, but the total soluble group HCl hydrolysis in general the total soluble group was higher than that of H2SO4 hydrolysis to obtain the.Different nitrogen levels had a certain influence on the soil organic carbon degradation and activity. Among them, the soil organic carbon activity index, with the increase of amount of nitrogen, showed decreased trend... |
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