| How to make use of corn stover is an important problem to be solved urgently in Chinese agriculture.Many studies have shown that the practice of corn stover application to soil is an important measure to improve the utilization ratio of corn stover and increases soil fertility.However,the influence of different ways and years of corn stover application on humus composition and humic acid structural characteristics in soil is not well understood.This study is beneficial to explore the difference of ways and years of corn stover application on humus composition and humic acid structural characteristics in soil,and provide theoretical basis for improving the soil fertility and carbon sequestration.Cultivation experiment was carried out to deals with the change of decomposition rate of corn stover and humus in soil.Micro area experiment was carried out to compare the difference of ways of corn stover application on humus composition and structural characteristics in soil.Field experiments were conducted to study the changes of soil humus composition and the structure with the increase of years.Results showed:(1)After the adding the corn stover,the decomposition rate of the corn stover increased rapidly and reached to the peak(194~1103mg/kg/d)in 0-24 days,and then the decomposition rate decreased gradually and tended to be stable in 25~300 days.The cumulative decomposition rate of stover showed a rapid growth in the early stage and a slow growth trend in the later period.The decomposition rate was the fastest when the full amount of corn stover was mixed with the black soil,which could be 82%.(2)Different ways of corn stover application had no significant effect on soil pH and electrical conductivity,The content of N,P and K in surface soil showed an upward trend with the increase of the application of the corn stover,corn stover deep incorporation promote soil available nutrient content increased significantly in the subsoil.varied with the time going on,it displayed an decreasing trend on the content of soil available nutrient.(3)Adding corn stover significantly increases the content of organic carbon in soil,the organic C contents in the soil decreased with the amount after the application of corn stover.When full-amount corn stover was mixed with soil,it was beneficial for the accumulation of organic C.corn stover incorporated to shallow layer(C1)with different amount had a great effect on SOC in the surface soil,corn stover deep incorporation(CSDI)increased significantly in the subsoil.varied with the time going on,CSDI displayed an decreasing trend on the content of SOC.(4)Adding corn stover and different ways of corn stover application(C1 with different amounts and CSDI)can improved the organic carbon contents of soil humic components,PQ,ΔlogK of HA and FA significantly.with the time going on,CSDI displayed an decreasing trend on the content of organic carbon in soil,FA,HM,ΔlogK of HA and FA.HA was opposite.PQ value changes significantly.(5)Cultivation experiment,micro area experiment,field experiment showed that corn stover application to soil can reduce the condensation degree,oxidation degree and thermal stability of HA,increase the content of aliphatic chain hydrocarbon,lower in aromaticity,make HA simpler in structure.In cultivation experiment,the structure of HA make simpler with the amount after the application of corn stover or full-amount corn stover was mixed with black soil.In micro area experiment,C1 treatments make HA simpler in structure with the amount increase after the application of corn stover,and the change is more obvious in the surface soil.In field experiment,CSDI is significant changes in HA,especially in the subsoil.With the days going on,in treatment CSDI,HA displayed an increasing trend in condensation and oxidation degrees and became lower in aliphaticity,higher in aromaticity,and more complicated in structure.(6)In field experiment,CSDI(2014)increases the content of crop yield by 6%.With the days going on,crop yield is higher than CK,tend to be lower. |
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