Characteristics and Planting Safety Assessment of As Content in Dryland Soil and Maize in Guizhou Province

Abstract

In order to understand the distribution characteristics of As content in dryland soils and maize seeds in Guizhou province and to evaluate the safety of maize cultivation, 468 natural soil samples, 1260 dryland surface soil samples, and 980 corresponding maize seed samples were systematically collected to determine their As content and basic physicochemical properties. The degree of contamination of the samples was evaluated by using the single-factor contamination index method. The results showed that: ① the range of ω(As) in dryland soil was 0.35-758.53 mg·kg-1, with a geometric mean of 23.28 mg·kg-1. The independent sample T-test showed that the As content of dryland soil in Guizhou province was significantly higher than that of natural soil ω(As) 21.29 mg·kg-1 (P<0.01), indicating the existence of arsenic accumulation effects in dryland soil; compared with the screening value of the "Agricultural Land Soil Pollution Risk Management and Control Standard" (GB 15618-2018), the excess rate of soil samples was 33.81%. ② Corn seed ω(As) ranged from 0.001 to 0.868 mg·kg-1, with a mean value of 0.064 mg·kg-1, and 0.61% of the corn seed samples exceeded the limit value of "Limits of Contaminants in Foods" (GB 2762-2017), with the exceeding points distributed in Bijie City, Qianxinan Prefecture, and Tongren City. ③ When corn seeds were used as feed and grain, maize could be safely grown in dryland soils in Guizhou province. This study showed that the soil As pollution in the dryland of Guizhou province was relatively serious, and overall safe maize cultivation can be achieved; however, the cultivation of maize around the As-related non-ferrous metal mining areas is still of concern.