Effect Of Biochar Addition On Decomposition Of Organic Carbon In Chinese Fir Plantation Soil

Biochar,has been suggested as one of the possible means to mitigate global warming.However,its role is underestimated in soil organic carbon mineralization and the input of fresh organic carbon.Firstly in this study,two kinds of biochar,produced by the litters of Schima superba and Cunninghamia lanceol,were produced at different pyrolysis temperature(from 250? to 750? at 100? interval)and the characteristics of biochars,such as carbon contents,yield,dissolved organic carbon(DOC),pH,volatile matter and ash,as well as production efficiency related to pyrolysis temperature were determined.And secondly,the fresh litter and three kinds of biochar(350?,550? and 750 ?)were chosen add to soil,respectively,though incubation conduct incubation experiment last for 84 days at 25?,we want to investigate the effect of biochar on the mineralization of native soil organic carbon and the decomposition rate of biochars.The major results are summarized as follows.With the pyrolysis temperature increase,carbon content,C/N value and ash,gradually increased.On the contrary,yield,dissolved organic carbon and volatile matter decreased.The pH of biochar is alkaline(except produced from 250?).Regression analysis shows that,he volatile substances of two kinds biochars were in significantly liner relationship with the pyrolysis temperature(p<0.01),statistical anaylisis show that under the same temperature level,the ashes,carbon contents and volatile substances indicators of black carbon produced by two different litters have not reached significant level.While,nitrogen content,C/N value and dissolved organic carbon reached significant level.Stable isotope 13C was used to study effects of biochar addition on decomposition of soil organic carbon.During the whole incubation process,the results showed that soil CO2 release rate had the similar trend with different biochars addition treatments,CO2 release rates were faster at the early stage of incubation proess,which slightly dropped from first to third day of the incubation process,while,increased from third to seventh day then change is slow,gradually tended to be stable.At theearly stage(0 to 14 d),the release rate of soil CO2 followed order BC350>BC550>BC750>CK,after adding biochar,soil mineralization rate are more relatively quick;at the late stage(14-84d),biochar added treatments shows no significantly difference between soil CO2 and control treatments.Indicating that biochar addition,at the early stage,it promoted the mineralization of soil organic carbon.The decomposition rate of biochars has two different stage,the early stage of the decomposition rates were faster,which slightly dropped,then keeped low.At the whole incubation process,the order of the decomposition rates of biochar was BC550>BC350>BC750,as 1.79%?1.74%and 0.64%.With the litter of Schima superba adding to soil,the decomposition rate of biochars was 1.94%,1.98%andl.17%.With the litter of Schima superba addition,the mineralization of biochars increased 10.42%?9.68%and 45.29%?Indicating that the litter of Schima superba addition,It promoted the mineralization of biocahr.