广西天等县耕地土壤酸化的初步研究

Soil acidification of cultivated land in Tiandeng County,Guangxi

【目的】研究广西天等县耕地土壤的酸化情况,为提高耕地质量、促进农业可持续发展提供科学依据。【方法】收集2007年启动的测土配方施肥项目资料,与第二次土壤普查资料作比对,分析两个时期该县耕地土壤pH值变化情况,并进行相关性分析。【结果】相对于第二次土壤普查,该县耕地土壤pH值总体平均下降0.73个pH值单位,微酸性至强酸性土壤样点所占百分比由9.8%上升到55.8%。非石灰岩母质发育的耕地土壤酸化程度较重,石灰岩母质发育的耕地或碳酸盐含量较高的耕地相对较轻。旱作连作土壤酸化程度较重,水稻连作次之,水旱轮作和玉米—黄豆轮作相对较轻。土壤酸化程度与氮肥投入和作物吸收带走氮素的盈余量呈正相关,与土壤有机质含量、水田土壤全氮含量均呈非线性高度负相关。【结论】广西天等县耕地土壤酸化现象比较突出,先天成土条件以及后天有机肥投入量少、过量施用氮素是其主要原因。

[Objective]In order to improve the cuhivated 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.