Effects Of Conservation Tillage On Soil Organic Carbon Fractions And Content

By setting long-term positioning experiments in Town of Lee’s,DingxiCity,Gansu Province,determining the different depths of soil organic carbon(SOC),humus total carbon (HOC),hot-water extraction carbon (HWC),readilyoxidation organic carbon (ROC) and dissolved organic carbon (DOC) content it’sunder no-tillage with straw mulch(NTS),ploughed tillage with straw mulch(TS),no-tillage(NT) and conventional tillage(T) for spring wheat-pea rotation corprotation, the results show that:(1) The two crop rotations of conventional tillage pattern under, under fourdifferent tillage patterns,the average contents of SOC, HOC, HWC, ROC and DOC insoil layer of0～30cm followed the order as NTS>T>TS>NT, The deal with thedifferent levels of SOC, HWC, ROC and DOC size relations are0~5cm>5~10cm>10~30cm; The changes of the HOC are same to the changes of SOC in NTSand NT, in TS and T changes is5~10cm>10~30cm>0~5cm,.The two crop rotations of conventional tillage pattern under, compared with Ttreatment, the conservation tillagepatterns of NTS、TS and NT increased the contentsof SOC, conservation tillage isbeneficial for carbon sequestration, among of them,NTS treatment was moreadvantageous to improving the soil organic carbon contents,by which to alleviategreenhouse influence. Thus, it should be recognized as the keyapproaches to sustainable agriculture and environment.(2)In2009~2011,the two crop rotations of conventional tillage pattern underevery treatment in0~30cm soil layer,SOC,HOC,HWC,ROC and DOC distributiontrend:2011>2010>2009.Under the conservation tillage SOC,HOC,HWC,ROC andDOC is increasing year by year in the short term.(3) The two crop rotations of conventional tillage pattern under Straw mulch andNo-tillage was make for increasing soil carbon pool management index, conventionaltillage was obviously superior to conventional tillage, Which covered by no-tillagestraw carbon management index in performance.(4) In both conventional tillage rotation sequences SOC, HOC, HWC, ROC and DOC of the relationship between the size without apparent change trend, but all arepositively correlated with SOC, and HOC,HWC,ROC and DOC four soil organiccarbon content change of relative than SOC change sensitive,in evaluation of differentcultivation measures the influence of soil organic carbon, HOC and HWC,ROC andDOC relative content also is an ideal target.For dry farming, tillage and straw mulch can effectively reduce carbon lossesresulting from agricultural soils due to farming, reduce cropland soil carbon releaseand enhanced soil carbon sequestration, and thus significantly increase SOC, HOC,HWC is, the ROC and DOC content. Two measures to maintain and improve soilfertility in rainfed land to enhance soil carbon sequestration potential of rainfed landis very good agricultural management practices.