A soil quality assessment under different land use types in Keriya river basin, Southern Xinjiang, China

Abstract

The process of oasisization leads to the transformation of natural land use to farmlands in the Keriya river basin. In order to investigate changes in soil quality during the process of oasisization, we established five experimental fields in the oasis-desert ecotone of the Keriya river basin, including farmlands(FL) and four typical natural lands natural forest (NF), saline and alkaline land (SAL), desert (D) and sand land (SL)) of the main local land cover. In this paper, a minimum data set of soil indicators was selected including soil water content indicator, pH, soil nutrient indicators and soil salinity indicators, with 100 soil samples collected within five land use types. Observations found significant differences in the fifteen soil indicators. These were used to calculate a soil quality index (SQI) and assessed using multivariate analyses (cluster analysis and principal component analysis, PCA) in order to determine the soil quality of the different land uses. Data indicated a clear difference in soil quality among the studied areas: low soil quality (SQI<0.55) in SAL, D and SL; intermediate soil quality (0.55<SQI<0.70) in FL and NF. Results suggested that the soil of the oasis-desert ecosystem has low soil water content, high concentrations of salt and a structureless soil with very low organic matter, but concentrations of soil nutrients increased and land improvement occurred after land use shifts from natural land uses to cultivation. The four natural lands have distinct soil characteristics, which should be considered during the process of soil reclamation.