Effects of aeolian processes on soil nutrient loss in the Gonghe Basin, Qinghai–Tibet Plateau: an experimental study

Abstract

The Gonghe Basin of northeastern Qinghai–Tibet Plateau is threatened by aeolian processes, soil nutrient loss, and desertification, where human activities have greatly increased over recent decades. However, the interactions between aeolian processes and soil nutrient loss remain poorly understood. Therefore, in this study, we employed a wind tunnel to simulate aeolian processes and soil nutrient loss affected by human activities such as tillage and trampling by livestock. Field investigations, wind tunnel experiments, and experimental analyses were conducted to assess the impacts of human activity (wholesale destruction of vegetation) and aeolian processes on soil nutrient loss and desertification in the Gonghe Basin. After grassland soil surface was disaggregated, sediments removed by high aeolian intensity (≥16 m s−1) ranged from 294.02 to 1012.73 g m−2, and wind erosion depths varied from 4.09 to 11.27 mm. High wind velocities resulted in losses of total soil organic matter (SOM) and total nitrogen (TN) by 7.56 and 0.38 kg ha−1, respectively. Under very high wind velocities (≥22 m s−1), losses of SOM and TN were 26.99 and 1.41 kg ha−1, respectively. Wind tunnel experiments indicate that in the Gonghe Basin, there were no significant correlations between wind velocity and the removal of SOM and TN; however, positive correlations were observed between wind velocity and total phosphorus (TP) and total potassium (TK). Aeolian processes remove TK and TP from the soil surface, which has a potential impact on vegetation because that K and P are essential nutrients for plant growth. In addition, most nutrients are enriched within fine particle fraction of soil. Nutrient loss caused by aeolian processes may therefore result in the degradation of farmland and grassland, which consequently may have triggered desertification in the Gonghe Basin.