Effect Of Long-term Continuous Cropping Cotton Soil Structure And Aggregate Stability Of Organic Carbon For Straw

In this study, the long-term continuous cropping of cotton locate a testing ground for the study of soil, through stratified sampling, measurement of soil aggregates under conditions of dry sieving structure and organic carbon, organic carbon component of acid hydrolysis and mineralization of soil organic carbon content to reflect the carbon component changes in the characteristics, analyzes the relationship between long-term continuous cropping cotton field soil aggregates structure and organic carbon fractions between straw to investigate the long-term stability of the Soil cotton field. Oasis Cotton straw for the rational use of technology to improve cotton field soil fertility and achieve scientific theory provide sustainable use of resources and guidance to regional agricultural development. The main conclusions are as follows: 1. Straw and long-term continuous cropping of cotton fields 0-60 cm soil layer >2mm sieve size fractions of dry aggregate content increased with soil depth increases, even as each was no significant difference between the life; no straw with the next >2 mm size aggregates content increased with continuous cropping significantly decreases with increasing soil depth increases. With the increase of continuous cropping, and improve the overall treatment of straw on the long-term mechanical stability even as the cotton fields of the three soil; no straw treatment under various soil MWD values with increasing continuous cropping showed a decreasing trend, either Straw Straw is still no deal, each Cropping MWD values with increasing soil depth increases. Straw treatment can improve the long-term continuous cropping of cotton fields 0-60 cm soil organic carbon levels aggregates, aggregates with increasing grade arabica organic carbon content greater increase in continuous cropping, the smaller size of the aggregates of organic carbon content of higher than the larger grain size, aggregates of soil organic carbon content of each grain with increasing continuous cropping of a certain increase; no straw treatment with exhibits contrary trend. Straw treatment under various size aggregates of organic carbon content than those without straw treatment. Whether or no straw Straw, the contribution rate of organic carbon in soil aggregates from> 2 mm size fraction of aggregates ah about 50%-70%, and with the increase of soil depth increases, while <2 mm size fraction of organic carbon in the contribution rate of aggregates showed a contrary trend. 2. Straw can promote the accumulation of continuous cropping cotton fields 0-60 cm soil TOC, and with continuous cropping increased TOC content increased; straw processing at each Cropping 0-60 cm soil organic carbon of the active ingredient(I and II) content increases as the number of years even after showing the first increase in a decreasing trend, while the biodegradable component content of the active ingredient content showed the opposite trend. Straw can significantly increase the long-term continuous cropping of cotton field 0-60 cm soil organic carbon content of active ingredients and biodegradable ingredients, the same trend with the TOC, and content of each component are 0-20cm> 20-40cm> 40-60 cm soil. Straw treatment under 0-60 cm soil organic carbon activity index(LIc) were less than no straw treatment, and in addition to continuous cropping 15 a outside, with the continuous cropping increase LIc decreased, 30 a reach a minimum; and straw conditions Under the 0-60 cm soil layer of soil organic carbon refractory index(RIc) were higher than non-treated straw and exhibit activity index(LIc) opposite trend, 0-20 cm soil RIc increased with continuous cropping on the rise, 20-40 cm and 40-60 cm soil in addition to continuous cropping 15 a, with continuous cropping increase RIc downward trend, 30 a reaching the maximum. 3. straw treatment significantly increased the 0-60 cm soil carbon mineralization(MC) and the content of MR, even with the increased number of years as an upward trend, with increasing soil depth is reduced, and the TOC content in the same trend, and the treatment of straw under the MC and MR were higher than those without straw treatment. Straw treatment, the soil mineralization rate(MC/TOC) increases overall continuous cropping is decreasing; no straw treatment of organic carbon mineralization rates even as the overall increase in number of years with a stable trend. Straw were increased long-term continuous cropping cotton fields mineralization of soil organic carbon accumulation emissions, with the extension of the incubation time increases. Straw treatment of soil respiration under three soil treatment entropy lower than those without straw, with the increase of continuous cropping decreases soil respiration entropy cash for each soil layer 40-60cm> 20-40cm> 0- 20cm; no straw treatment of soil respiration under continuous cropping with increasing entropy increases with straw handle opposite trend.