Effects Of Changing Carbon Input On Soil Organic Carbon Components In Camphor Plantation

Soil organic carbon(SOC)is an important component of soil carbon pool and an important index to measure soil quality,which affects the global carbon cycle.Active organic carbon,such as microbial biomass carbon(MBC),dissolved organic carbon(DOC),easily oxidized organic carbon(EOOC),light fraction organic carbon(LFOC),is more active and easier to be utilized.It is easily affected by environmental conditions,plants and human factors.However,plants mainly input organic carbon into soil through decomposition of litter and root turnover and secretion.Therefore,studying the effect of carbon input on soil organic carbon composition is helpful to improve the availability of soil carbon and regulate the storage of soil carbon pool,thus influencing the global carbon cycle.In this study,camphor forest in Changsha Forest Botanical Garden of Hunan Province was taken as the research object,Through DIRT(Detritus Input and Removal Treatments)experiment(Control check CK,Remove litter RL,Double litter DL,Remove root RR,Remove litter and root RRL,Remove litter and double litter RRDL),the dynamic changes of soil carbon composition and its influencing factors in soil at different depths after changing carbon input were studied.The main results are as follows:1.Soil chemical properties under different carbon inputs were studied.The results were as follows:the response of soil pH to carbon inputs varied greatly in different seasons,and soil pH under DL treatment increased significantly in summer,reaching 4.65;Soil pH under RL,DL,RRL and RRDL treatments increased significantly in autumn,reaching 4.75,4.61,4.55 and 4.58,respectively.Soil pH under RL and DL treatments increased significantly in winter,reaching 4.93 and 4.99,respectively.SOC content was significantly increased by RL and DL treatments in summer,RL,DL and RRL treatments in autumn and all treatments in winter,and DL treatment had the highest SOC content in all seasons,in which the content reached 23.85 g/kg in summer,an increase of 148%compared with CK.The response of soil TN to carbon input in summer and autumn was the same as that of SOC.In winter,soil TN content increased significantly under RL,DL,RRL and RRD treatments,also showing the largest increase in DL treatment.In winter,DL reached 1.73 g/kg,an increase of 78%compared with CK.In summer and autumn,soil TP content was significantly increased under DL,RR and RRDL treatments.In winter,soil TP content was significantly increased under DL treatment,and the increase rate was the highest under DL treatment,in summer,it reached 0.2883 g/kg,an increase of 26%compared with CK.2.The soil organic carbon components under different carbon input were studied.The results are as follows:RL,DL and RRL treatments in summer,RL and DL treatments in autumn,and RL,DL and RRDL treatments in winter all increased soil LFOC content,and the increase of DL in summer was 0.37 g/kg,which was 311%higher than that of CK.Soil HFOC content was increased by RL,DL and RRL treatments in summer,RL,DL,RRL treatments in autumn and RRL treatments in winter,and the increase of DL in summer was 23.47 g/kg,which was 242%higher than that of CK.All treatments could increase soil DOC content,but different soil layers had different responses.Taking the surface layer as an example,the increase amplitude of RL treatment was the largest in summer,RRL and DL in autumn and winter,respectively.The soil DOC content under autumn RRL treatment was 245.41 mg/kg,which was increased by 78%compared with CK.In summer and autumn,soil EOOC content was significantly increased under RL and DL treatment.In winter,only DL treatment significantly increased soil EOOC content,which also showed the largest increase in DL treatment,reaching 5.3 mg/gC in summer,which was 166%higher than CK.The response of MBC to the input of soil carbon source was consistent in all seasons,which showed that soil MBC content significantly increased under DL treatment,and reached 359.01 mg/kg in winter,which was 37%higher than that of CK.3.Impact factor to study the components of soil organic carbon,and the results were as follows:the soil chemical properties and components are closely related to the soil organic carbon,of which only TP and MBC,TP and no significant correlation between DOC,TN and TP,MBC and correlation between DOC significantly(P<0.05),and the different characteristics of other correlation between carbon components significantly(P<0.01).Seasonal influence on LFOC,HFOC,root treatment on the influence of DOC,litter,season,and the interaction of both no significant impact on EOOC,besides,litter,root,season,soil depth,and their interactions on the soil LFOC,HEOC,DOC,EOOC,MBC extremely significant effect(P<0.01).In conclusion,different carbon inputs had significant effects on soil carbon components,but the changes of each component were not the same and changed with the seasons.The addition of litters promoted the accumulation of SOC,DOC,EOOC,LFOC and HFOC,and the removal of litters promoted the accumulation of SOC,DOC,EOOC,LFOC and HFOC to a certain extent.However,the effect of litters on soil carbon componented gradually decreased with the seasons,and the removal of roots was not conducive to the accumulation of SOC,MBC,EOOC,LFOC and HFOC in soil.The sensitivity of each treatment to different carbon input was different,and some components are transferred in the soil layer.