[Distribution and enrichment characteristics of soil nutrients in the nebkhas profile of Nitraria tangutorum in Gahai Lake Area, Qaidam Basin.]

Abstract

As a special bio-geomorphic landscape in the Qaidam desert area, Nitraria tangutorum nebkhas play a critical role in fixing quicksand, improving soil quality, and maintaining the stability of regional ecological environment. Taking the N. tangutorum nebkhas with coverage of approximately 15%, 25%, 45% and 60% in Gahai Lake area of Qaidam Basin as the research objects, we analyzed the vertical distribution and enrichment characteristics of soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP) and available potassium (AK). The results showed that the contents of SOM, TN, TP, TK, AN, AP and AK varied in the range of 1.67-10.22 g·kg-1, 0.05-0.42 g·kg-1, 0.31-0.54 g·kg-1, 15.87-18.84 g·kg-1, 2.26-11.68 mg·kg-1, 0.80-15.00 mg·kg-1 and 45-161 mg·kg-1, respectively. Vertically, soil nutrients in the N. tangutorum nebkhas with 15% coverage showed a decreasing trend first then increased, and then decreased again with the increase of soil depth, except for TP, which did not show any significant change. In the nebkhas with 25%, 45% and 60% coverage, SOM, TN, AN, TP and AP all showed a decreasing trend with increasing soil depth ,whereas TK and AK did not change significantly with soil layer. Above the nebkhas ground level of N. tangutorum, SOM, TN, TK, AN, AP and AK were all enriched, especially in the surface layer.Aamong all the nutrients, the enrichment rate of AN reached 5.19. In addition, below the nebkhas ground level of N. tangutorum, TN, AN, TK, AK and AP also showed enrichment. SOM, TN, AN, TP, AP, TK and AK were all significantly positively correlated with soil water content, and negatively correlated with altitude. All nutrients except TP were mainly affected by altitude. In conclusion, soil nutrient content of N. tangutorum nebkhas was the highest in the surface layer, the enrichment effect of which was not only reflected in the interior of the nebkhas, but also below the ground level of the nebkhas. Our results could provide reference for the scientific utilization of N. tangutorum nebkhas and ecological environment protection in Qaidam Basin area.