Comprehensive evaluation of agricultural soil fertility along the Weihe River Basin in Shaanxi Province, a tributary of the Yellow River

The comprehensive evaluation of agricultural soil fertility is an important link for ecological protection and sustainable agricultural development in the Weihe River Basin of the Shaanxi section of the Yellow River tributary. In this study, the Weihe River Basin of Shaanxi Province is taken as an example, as the research area. Agricultural soil samples are collected from 13 representative locations along the Weihe River Basin in Shaanxi Province. Eight physical and chemical fertility indicators are measured, including soil pH, electrical conductivity, organic matter, total potassium, available potassium, total phosphorus, available phosphorus, and total nitrogen, as well as three biological fertility indicators, namely urease, sucrase and catalase. Using principal component analysis (PCA) and Nemerow index method (Nemerow), a composite index of soil fertility in the area is calculated and the two are validated against each other to arrive at a qualitative status of soil fertility in the area. The analysis and testing results indicate that: ① The soil pH in this area is generally high, with a mean value of 7.99 and weak alkalinity. The mean content of organic matter is 17.295 g/kg, while the mean contents of total potassium, total phosphorus, and total nitrogen are 6.17 g/kg, 1.06 g/kg, and 1.27 g/kg, respectively. The mean contents of available potassium and available phosphorus are 133.46 mg/kg and 16.02 mg/kg, respectively. ② The results of comprehensive fertility assessment of Weihe River soil in Shaanxi Province indicate that the average fertility score by PCA is -0.0015, while the average comprehensive fertility score using Nemerow index method is 1.342. Based on the criteria for soil fertility evaluation using principal component analysis and Nemerow index method, it shows that the agricultural soil in the Weihe River Basin in Shaanxi has a moderate level of comprehensive fertility, with moderate nutrient content in the soil that can meet the growth requirements of general crops, making it suitable as a planting base for ordinary farmland. ③ The main factors affecting fertility are arid climate and geographical location, followed by human factors. This study promotes the utilization of agricultural soil resources in the Weihe River Basin and has important research significance for ensuring food security, economic development, and ecological construction in Shaanxi Province.