The Promotion Effects Of Different Reclamation And Fertilization Measures On Soil Organic Carbon And It's Mechanisms

The reclamation of the damaged land in coal mining areas is an important measure to restore and improve the productivity of farmland.Soil organic carbon is the core of soil fertility,and its different components are highly heterogeneous.Therefore,studying the characteristics of soil organic carbon sequestration under different reclamation methods can provide a scientific theoretical basis for the restoration of reclaimed farmland in coal mine areas.In this study,three typical reclamation methods of covering reclamation,mixed pushing reclamation and topsoil stripping reclamation under different fertilization measures were taken as research objects.In the grouping of soil organic carbon,a combined physical-chemical fractionation method was used to observe the characteristics of various fractions of soil organic carbon under different fertilization treatments.Furthermore,the quantitative relationship between the organic carbon content of each fractions of the soil and the external carbon input is further analyzed,and the characteristics of soil carbon sequestration are discussed.The main results and conclusions obtained are as follows:?1?Each fertilization treatment significantly increased the organic carbon storage of the reclaimed soil organic carbon in the coal mining area,and the most obvious effect was the treatment of applying organic fertilizer.Compared with CK treatment,about covering reclamation,M treatment significantly improved the total organic carbon and the organic carbon reserves of active fractions;About mixed pushing reclamation and topsoil stripping reclamation,The HMNPK treatment significantly improved the total organic carbon and the organic carbon reserves of each fraction,among which the most obvious effect was the activated organic carbon component.The results show that organic fertilizers,especially high-level organic fertilizer combined with chemical fertilizers,are effective measures to quickly restore the soil organic carbon reserves in coal mine reclamation areas,in which the activated organic carbon fractions can respond more sensitively to different fertilization measures.?2?In the correlation between the amount of organic carbon sequestered in the reclaimed soil and the amount of externally accumulated carbon input,the covering reclamation showed a significantly positive linear relationship?p<0.05?,and the performances of mixed pushing reclamation and topsoil stripping reclamation were both extremely significant positive correlations?p<0.01?.It showed that none of the reclaimed soil has reached carbon saturation.The carbon sequestration efficiency of soil organic carbon in different reclamation methods showed topsoil stripping reclamation?43.0%?>mixed pushing reclamation?20.9%?>covering reclamation?15.9%?.It showed the topsoil stripping reclamation had the best effect on the restoration of soil organic carbon,and the newly fixed organic carbon mainly entered the unprotected carbon fraction first.?3?In covering,mixed pushing and topsoil stripping reclamation,the fractions with the highest changes under unit carbon input(1 t C·hm^-2)were all unprotected carbon fraction(0.23,0.09,0.18 t C·hm^-2).reclamation could increase the coarse aggregates contents,i.e.increase the friable unprotected coarse and fine particle C,and combined application of high manure with NPK application performs better than with NPK together.However,as the newly increased soil carbon are quite active,so long-term organic manure input is necessary for the recovery of soil function in coal mine reclamation.In summary,the use of topsoil stripping reclamation methods and the application of high-level organic fertilizer combined with chemical fertilizers are more conducive to the restoration and improvement of soil organic carbon in reclamation farmland of coal mine.