Variation of soil microbial biomass carbon,soil microbial biomass nitrogen and nitrogen mineralization potential in different soil types on the Loess Plateau Carbon mineralization potential in soils under different degraded sandy land Comparison of mineralization rates and nitrogen potentials in foreshore reclamation long-term cultivated paddy soils and adjacent upland soils Effect of fertilization constitution on sulfur fertility development and supplied S ability of red paddy soil NITROGEN SUPPLY POTENTIALITY OF UPLAND SOILS Long term impact of different soil management on nitrogen supplying potential in rice based cropping system