茶园土壤pH变化对土壤中铝特性的影响

土壤中铝的毒性强弱取决于铝的形态。为了解茶园土壤中铝的特性,以江苏省7个长期定位观测茶园为研究对象,采用化学连续提取法测定不同条件下土样中不同形态的铝含量,研究茶园土壤pH升高或降低过程中铝的形态转化及其影响因素。结果表明,茶园土壤在酸化过程中活性铝溶出明显增强,不同形态的铝含量有明显差异,依次为腐殖酸铝(Alh)铝的水合化物和氢氧化物(Aloh)交换态铝(Alex)有机态铝(Alo)水溶态铝(Alw)无机吸附态铝(Alino);土壤pH、有机质和酸容量是影响铝形态的重要因素;茶园土壤酸化过程中铝的水合化物和氢氧化物、无机吸附态铝以及水溶态铝会转化为交换态铝。土壤pH升高,交换态铝转化成羟基铝;有机结合态铝会影响其他铝形态的转化,腐殖酸铝在土壤pH升高时转化为铝的水合化物和氢氧化物。

Effects of Soil pH on Characteristics of Soil Al in Tea Plantations

The toxicity of aluminum (Al) in soils depends on its chemical forms. Tea (Camellia sinensis L.) is typical acidophilous and poly-Al plants. In order to understand the characters of Al in tea plantation soils, forms of active Al were studied based on the analysis of soil samples at different tea plantations in different years with sequential chemical extraction procedure, the transformation of Al forms and affecting factors for active Al in the plantation in the process of soil pH increased or decreased were discussed to understand the characteristics of Al. The results showed that digestion of active Al was enhanced during the soil acidification, the difference of Al contents in different forms were significant, decreased in the order of humic acid aluminum (Alh) > Al of hydrous oxide and hydroxide (Aloh) > exchangeable Al (Alex) > organic combined Al (Alo) > water soluble Al (Alw) > inorganic adsorption Al (Alino). Alh and Aloh constituted the dominant part of the total active Al, accounting for more than 80% of the total Al. Soil pH, organic matters and acid capacity were the important factors of Al forms. Aloh, Alino and Alw were translated into Alex during the process of soil acidification, but the situation was opposite with the increase of soil pH. Alo affected the transformation of other Al forms, the content of Alh decreased and was translated to Aloh with pH increased, on the contrary, the content of Alh increased with the process of soil acidification, meanwhile, it promoted the hydrolysis of Alino.