Effect Of Defferent Corn Stover Incorporation And Land Use Pattern On Composition Of Soil Humus In The Surface And Subsurface Layer

In order to explore the changes of soil organic matter and humus composition under different straw mulching and land use patterns,the long-term micro-area test of black soil in the experimental field of Agricultural university for 12 years,as well as chenjiadian and songyuan were carried out.The soil samples treated by field experiments in jiutai district were studied Potassium dichromate oxidation method,humus composition modification method,wet sieve method and other test methods were used to determine the content of soil surface and sub-surface organic carbon,carbon of each component,soil nutrients and soil aggregates at all levels,further improve the physical and chemical properties of the soil,supply certain nutrients,increase the content of organic matter in the soil,improve the structure of the soil,and loosen the soil.The main conclusions are as follows:(1)in the case of not fertilizer,straw deep(C3)also increased the soil surface(0 ~ 20 cm)of extractable humus(HE),humic acid(HA),fulvic acid(FA)content and relative content,PQ value increases,reduces the soil organic carbon(SOC)and humin(HM)content and relative content,1/3 straw returned(C1)reduces the soil surface(0 ~ 20 cm)of HA and FA content,two-thirds of straw returned(C2)can improve the surface(0 ~ 20 cm)soil SOC,HE,HA,FA,HM and PQ levels;Straw depth also increased soil SOC,HE,HA,FA and HM in subsurface layer(20 ~ 40cm).(2)in the case of fertilizer application,straw application of fertilizer increased the SOC,PQ and HM content in the surface soil(0 ~ 20cm),and reduced the content and relative content of HE,HA and FA in the soil.3/3 straw mulching(CF2)increased the content of HE,HA and FA in subsurface(20 ~ 40cm)soil,and 2/3 straw mulching(CF1)increased the content of SOC and PQ in subsurface(20 ~ 40cm)soil,and reduced the content of HM.(3)in the case of different land use modes,the soil organic carbon content is NG>CS>BS>BS+CS.The natural growth of vegetation and the land for returning straw to the field for corn are conducive to improving the soil organic carbon content.NG soil had higher content of HE,HA,FA and HM,followed by CS soil HA.The ratio of humus components to organic carbon in soil with different land use patterns is: fusulin carbon(FAC)< humin carbon(HAC)< humin carbon(HMC).CS soil humus degree in the surface is the largest,BS in the subsurface soil humus degree significantly accelerated.NG is beneficial to the increase of the proportion of HA in soil organic carbon in surface soil,NG is not conducive to the increase of the relative content of FA in surface soil,and CS treatment is higher than BS.The FA content of subsurface soil in the natural vegetation growth area(NG)decreased,while the soil HM content in the corn land(CS)increased.In general,the natural growth of vegetation and the land for returning straw to field are conducive to the increase of soil organic carbon and humus component carbon content,and the acceleration of soil humination process,but not conducive to increasing the proportion of soil humus in soil organic carbon.(4)in the field experiment,the enrichment and tillage treatment in chenjiadian area reduced the pH value and alkali-hydrochloric nitrogen content of soil surface and subsurface,and increased the humus degree of soil surface and subsurface.Enrichment process increases the effective phosphorus content in soil,HE,HA,FA,HM content,increased the surface soil SOC,conductivity,HE,FA and HA content,in addition to 0.25 ~ 2 mm graded aggregate content is significantly higher than the other grade,compared with conventional tillage,straw returned more conducive to the surface and the surface formation of rough aggregate(> 2 mm)and fine aggregate(0.25 ~ 2 mm),is not conducive to form micro aggregate(0.25 ~ 0.053 mm)and powder clay(< 0.053 mm),The content of coarse aggregate(>,2mm)and fine aggregate(0.25 ~ 2mm)in the enrichment treatment was significantly higher than that of CK.The organic carbon content of the enriched straw returning to the field in the surface and sub-surface soil in jiutai area is higher than CK,and the organic carbon content of the enriched soil is sub-surface >.In songyuan area,the soil organic carbon content was reduced by the enriched straw returning to the field,and the organic carbon content was subsurface < surface layer.