Effects of mineral and particle composition on the nutrient and salt content of farmland soil in the Hotan region

In this study, we analyze the soil mineral and particle composition as well as the reasons for the low soil nutrient content in the Hotan region. A grid sampling method was used to set up 255 sampling points in a cultivated land, and the correlations among soil mineral composition, particle composition, nutrients, and salts were analyzed. The soil particles in the Hotan region were mainly sand (50.30% by mass) and silt (41.40%), with only 8.30% clay. The sand content was significantly negatively correlated with organic carbon, total nitrogen, available nitrogen, total phosphorus, available phosphorus, total potassium, total salt, available iron, available manganese, available copper, and available zinc (PP−1), medium to low levels of total nitrogen (0.76 g·kg−1), total potassium (16.24 g·kg−1), and available potassium (182.71 mg·kg−1); the salinization degree (total salt content 2.99 g·kg−1) was moderate; the available iron (28.4 mg·kg−1) and zinc (1.6 mg·kg−1) contents were at high and extremely high levels, and the available manganese (9.1 mg·kg−1) and copper (0.7 mg·kg−1) contents were at medium levels, which might be related to the rich adsorption sites provided by silt. The mineral composition mainly comprised primary minerals, such as quartz (73.4%), with a relatively high calcite content (12.1%) in secondary minerals, whereas the clay mineral content was low (10.2%). The clay mineral content was significantly positively correlated with total potassium, organic carbon, available iron, available manganese, available copper, and available zinc (PP−1) (P<0.05). The low clay mineral content and high sand content are the reasons for the low soil nutrient content in the Hotan region. Therefore, increasing the application of organic fertilizers and clay minerals to provide nutrients and promote aggregate formation may be an effective measure for improving the fertility of farmland soil in the Hotan region.