黔西北茶园土壤活性铝的形态分布及影响因素

土壤中各形态活性铝的质量分数决定了铝毒性的强弱,为了解茶园土壤中活性铝的形态分布及其影响因素,以采集于贵州西北部的106个茶园土壤样品为材料,采用化学连续提取法测定土壤中各形态活性铝的质量分数并分析其影响因素. 结果表明:不同类型土壤中w(Tac-Al)(Tac-Al为活性铝)表现为黄壤＞黄棕壤＞棕壤＞褐土；土壤中各形态活性铝质量分数分布略有差异,表现为w(Hy-Al)(Hy-Al为铝的水合氧化物与氢氧化物)＞w(Ha-Al)(Ha-Al为腐殖酸螯合态铝)＞w(Ex-Al)(Ex-Al为可交换态铝)＞w(Or-Al) (Or-Al为有机结合态铝)＞w(In-Al) (In-Al为无机吸附态铝),其中,结合较稳定的Hy-Al和Ha-Al占优势,二者质量分数之和在w(Tac-Al)中所占比例接近70.0%. 相关性分析显示,土壤中各形态活性铝质量分数之间均呈极显著正相关(P＜0.01),其中,w(Hy-Al)与w(Tac-Al)之间的R高达0.975(P＜0.01),接近线性关系；w(Tac-Al)随着土壤pH的降低而升高,随着w(有机质)的增加而增大. 因此,土壤中w(Tac-Al)并不由w(总Al)决定,而是受土壤pH和w(有机质)等因素的综合影响. 

Distribution of Active Aluminum Forms and Affecting Factors in Tea Plantation Soils from Northwest Guizhou

The toxicity of active aluminum in soils is mainly associated with its chemical forms. In this study, forms of active Al in a tea plantation in northwest Guizhou were studied based on analysis of 106 soil samples with sequential chemical extraction procedure, and the affecting factors for active Al in the plantation were discussed. The results showed that the total Al contents in different soils decreased in the order of tan soils＞brown soils＞yellow soils＞yellowish-brown soils. However, w(Tac-Al) in different soils decreased in the order of yellow soils＞yellowish-brown soils＞brown soils＞tan soils. The slight difference existed in the distribution pattern of active Al contents for different soil types. Hy-Al and Ha-Al, which were relatively stable forms, constituted the dominant part of the total active Al content, accounting for nearly 70.0% of the total. The average content of different active Al forms was as follows:Hy-Al＞Ha-Al＞Ex-Al＞Or-Al＞In-Al. In the present study, some highly significant correlations were found between different active Al chemical forms with correlation analysis. Especially, the correlation coefficient between w(Hy-Al) and w(Tac-Al) was up to 0.975 (P＜0.01). Additionally, the contents of Tac-Al in the soils from the studied region were found to generally increase with an increase in soil acidity and soil organic matter. The total Al content was not responsible for the total active Al content in soils. It was found that soil acidity and soil organic matter were the affecting factors of active aluminum in the soils.