Relationship between soil organic carbon with other soil physical and chemical indexes of different land use types.

【Objective】This study aimed to research the relationship between soil organic carbon and other soil physical and chemical indexes.【Method】Field investigation and laboratory analysis using grey correlation and stepwise regression analysis were applied to analyze soil properties including total nitrogen,available P,available K,pH and microbial C in Aohan County of Huanghuadianzi Small Watershed.Eight land use types,Prunus sibirica land,Caragana microphylla land,Populus simonii land,Ulmus pumila land,Pinus tableulaeformis×Prunus sibiricaland,secondary forest of natural bush land,natural grasslandand agricultural land were adopted to explore the correlation between soil organic carbon and other soil physical and chemical indexes.【Result】The results showed that soil organic carbon contents of Prunus sibiricaland,Caragana microphyllaland,Populus simonii land,Ulmus pumilaland,natural grassland,Pinus tableulaeformis×Prunus sibiricaland,secondary forest of natural bush land and agricultural land with 0-100cm soil layer were 7.72,5.23,7.40,6.11,3.14,10.26,17.51and 5.33g/kg,respectively and the differences were significant(P0.05).The grey relational coefficients between soil total nitrogen,pH,microbial biomass carbon,soil available K,available P and organic carbon were 0.70,0.66,0.63,0.57and 0.55,respectively.An optimal stepwise regression equation between organic carbon and other soil chemical indexes was built as well.【Conclusion】The contents of soil organic carbons of different land use types were in a decreasing order of secondary forest of natural bush landmixed plantation forestpure plantation forestagricultural landnatural grassland.The grey relational coefficients were in a decreasing order of total nitrogenpH microbial Cavailable Kavailable P.An optimal stepwise regression equation between soil organic carbon(Y) and total nitrogen(X 2) and pH(X 5) was obtained(Y=-6.269 8+ 19.383 2 X 2-0.010 2 X 5,R 2 =0.85).