Response of soil physical, chemical and microbial biomass properties to land use changes in fixed desertified land

Fixed dunes are indicators of successful recovery of desertified land after several years of vegetation restoration. Land use profoundly influences soil properties; however, the effects of changes in land use, after the dunes are fixed, on soil physical, chemical and microbial biomass properties are still unclear. This study investigates the soil physical and chemical properties and soil microbial biomass in a desertified land located in the Xiaojihan desertification control station in northern Shaanxi province, where land use changed from shrub land to arboreal land, arable land and nursery garden. No significant changes in soil properties were found when shrubland was changed to arboreal land. However, changing the fixed desertified land from shrub land to arable land and nursery garden decreased soil porosity, but significantly increased soil bulk density (BD), soil organic matter (SOM), cation exchange capacity (CEC), total nitrogen (TN) and available nutrients (N, P, K). Soil microbial biomass carbon (MBC), nitrogen (MBN) and phosphorus (MBP), as well as microbial quotient (MBC/SOC, MBN/TN, MBP/TP), decreased significantly. No significant changes were detected in soil texture, total phosphorus (TP) and total potassium (TK). Results of this study indicated that agricultural land use can improve the fertility of fixed desertified land; however, soil microbial biomass could decrease. Therefore, conversion of fixed dunes to agricultural usage is full of risks.