Distribution Pattern of SN in Qinghai-Tibet Plateau and Its Relationship with Environmental Factors

Studying the distribution pattern and driving mechanism of Soil Nitrogen (SN) in the agricultural areas of the Qinghai-Tibet Plateau is of certain significance for the rational use of N fertilizer, improving the quality of land use and protecting the environment. The SN content of cultivated soil in Qinghai-Tibet Plateau agricultural areas was analyzed by combining geographical and meteorological factors. It was found that the average Soil Total N (STN) in farmland was 2.4690 g/kg, which was the first class standard (>2.0 g/kg) of nutrient classification standard in the second national soil census. Horizontally, the areas with low N are mainly concentrated in the southwest of the Qinghai-Tibet Plateau and the high in the southeast and eastern regions of the Tibetan Plateau. From the vertical distribution pattern of 2000 m to 5000 m, it gradually decreases with the increase of altitude. The climatic factors affecting the STN are daily average temperature ≥ 10°C accumulated temperature > annual evaporation > daily average temperature ≥ 0°C accumulated temperature. The climatic factors that affect the Soil Available N (SAN) are daily average temperature ≥ 10°C accumulated temperature > daily average temperature ≥ 0°C accumulated temperature > annual evaporation> annual sunshine hours> monthly average maximum temperature > annual precipitation amount.