ABSTRACT
Selenium (Se) plays an irreplaceable key role in nutrition, including lipids, proteins, and other microelements. The surface soil in Guanzhong area is basically alkaline, therefore, the evaluation standard of Se-rich soil is only for alkaline soil. When soil Se and crop Se showed significant linear correlation, a regression model was established. According to the principle of geochemistry statistics, the grading boundary of Se content in surface soil was determined by two methods: Cumulative frequency method and iterative elimination method. The statistical values of low value area, low background area, and background limit obtained by the two methods are basically the same, and the lower limit of abnormal area is 0.22 mg/kg. According to the geochemical anomalies of Se in surface soil and the results of the membership function of Se in wheat and soil, it is reasonable to define the evaluation standard of alkaline selenium-rich soil in Guanzhong region of Shaanxi Province as 0.22 mg/kg.
