Soil acidification of cultivated land in Tiandeng County,Guangxi

[Objective]In order to improve the cultivated land quality and to provide scientific basis for sustainable development of agriculture, the status of soil acidification of cultivated land in Tiandeng County, Guangxi was analyzed by comparing soil data collected during two investigation periods. [Method]The soil data including soil type, location condition, management and utilization status of soil, and physico-chemical properties,etc., were collected from Tiandeng County, Guangxi in 2007. These data were compared with those collected from corresponding sampling sites in the second soil survey, in order to study the changes in soil pH of cultivated land to analyze the dynamic variation rule of soil pH during the time course between two investigation periods. [Result]The average soil pH of Tiandeng County was found to decrease by 0.73 unit and the percentage of acid soil samples increased from 9.8 to 55.8%. The cultivated land soil developed from non-limestone parent material was acidified acutely, while the soils developed from limestone parent material or soils containing high carbonate were acidified to a relatively lesser extent. The acidification of soils was found to be most pronounced after continuous cropping in dry lands, followed by rice cropping, paddy rice-upland crop rotation and corn-soybean rotation. The degree of soil acidification was positively correlated with the amount of nitrogen fertilizer application and apparent value of soil nitrogen. A high negative non-linear correlation was found between the degree of soil acidification and organic matter contents of soil and total nitrogen in paddy field. [Conlusion]The results indicated that the soil acidification in Tiandeng County, Guangxi was relatively severe due to excessive application of nitrogen fertilizers and less organic fertilizer, low quality of soil parent material and lesser organic matter content of the soils.