This article investigates trends in changing values of arsenic concentration in the plow layer under different conditions of soil moisture in the central region of Thailand. The study consists of two experiments: (1) examining the relationship between the vertical dynamics of As and soil moisture, and (2) exploring the effects of soil surface water evaporation on As speciation transformation and vertical dynamics. The experiments were conducted at the greenhouse facility of the Faculty of Environmental Culture and Ecotourism at Srinakharinwirot University. The evaporation rate of the greenhouse was measured to be 0.000104 mm/m2/h, and the soil permeability coefficient was 0.0014 cm/s. The effects of soil moisture on the vertical distribution of arsenic was found to be significant (p<0.05), particularly on Day One, in the layer 0–10 cm. In layers 11–20, 21–30, and 31–40 soil with 40% moisture showed higher concentrations of arsenic than soil with moisture levels of 10% and 20% (p<0.05). The pattern of As available for vertical movement in the plow soil layer showed great variability, especially in the 11–20 cm, 21–30 cm, and 31–40 cm layers. The most notable increase was observed at a 40% moisture content. The principal component analysis (PCA) test found that PC1 was most influential on the soil layers 21–30 cm and 31–40 cm, while PC3 highlighted arsenic concentrations in layers 0–10 cm and 41–50 cm. The movement of arsenic through evaporation from below the plow showed great variability between layers with the most stable concentrations being observed on the 14th day. However, the research showed that arsenic moves vertically in acidic soil rather than evaporating to the soil surface.