SOIL ACIDIFICATION OF CULTIVATED LAND IN HAINAN ISLAND, CHINA

Based on the soil pH data of cultivated land in Hainan Island in 1980s and 2010s, this study focused on research on soil acidification characteristics of cultivated land in Hainan Island, identified the change pattern of soil pH in the two periods, and studied the spatial and temporal changes of soil pH of cultivated land in Hainan Island in the recent 30 years using geostatistics, clarified the characteristics of soil pH change in Hainan Island, revealed the area of soil acidification in the Island, and identified significant areas of acidification, providing data support for controlling soil acidification in Hainan Island and tropical areas. The results showed that the soil in Hainan Island was generally acidic with a soil pH of 5.3, and varied by city and county. The average soil pH in Changjiang and Dongfang (western Hainan Island) and Sanya (southern Hainan Island) was the highest, reaching 5.7, while that in Qiongzhong was the lowest at 4.8. In the past 30 years, the grade distribution of soil pH in Hainan Island has changed to some extent, and the proportions of the third and fifth grades have gradually increased. The pH of cultivated soil in Hainan Island has declined overall, and its average pH decreased to 5.3 from 5.7 in the 1980s.