Variation in soil nutrients in grasslands along the Kunes River in Xinjiang, China

Abstract

Nutrients in the soil are important determinants of soil fertility, and influence crop yields. In recent years, soil fertility along the Kunes River in Xinjiang, China has decreased due to changes in land use and overgrazing. This study evaluated the distribution and spatial variation of soil nutrients in grasslands by taking and analysing 273 samples from 30 locations along the Kunes River; each sample was taken within a 1 m depth of the surface. Quality indicators referring to soil properties, including alkali nitrogen (N), available phosphorus (P), available potassium (K), organic matter (OM) and pH were analysed. In addition, the trace elements, iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) were estimated. The results showed that N, K, OM and Fe in the soil decreased as the depth from ground surface increased. Moreover, the pH of surface soil at higher elevations (>990 m) was lower than that at lower elevations (<990 m). In the surface soil, correlation coefficients of elevation, OM and pH with other indices were significant, but those of Mn, Cu and Zn were not. Significant changes in the amount of N, P, K and OM in the surface soil increased from west to east along the river. The amount of soil OM was low in this area, from 1.40 to 5.63 mg kg−1; this suggests a need to improve the soil's OM by such means as changing land use and agricultural practice. Understanding the variation in and characteristics of soil nutrients may be beneficial for grassland conservation, responsible use and sustainable agriculture.