植茶年限对土壤酸度及其团聚体交换性酸分布的影响

为明晰土壤酸度与团聚体交换性酸对植茶年限的响应特征，采用野外实地调查和室内分析相结合的方法，以植茶16、23、31和53 a的土壤为研究对象，开展不同植茶年限对土壤酸度及其团聚体交换性酸分布的影响.结果表明:①随着植茶年限的延长，土壤pH逐渐降低，交换性氢、交换性铝和交换性酸含量均呈升高的趋势.各植茶年限土壤0~20 cm土层pH均低于>20~40 cm土层，而交换性氢、交换性铝和交换性酸含量则表现出相反的变化趋势，且交换性氢含量在植茶23 a后的增幅可达21.29%. ②土壤交换性氢、交换性铝和交换性酸含量均随团聚体粒径的减小而升高，各粒径团聚体交换性氢、交换性铝和交换性酸含量随植茶年限的延长而逐渐升高. ③各植茶年限土壤团聚体交换性氢的分配比例均远低于交换性铝.随团聚体粒径的减小，各植茶年限交换性氢的分配比例均呈升高的趋势，而交换性铝的分配比例则呈降低趋势. 0~20 cm土层各粒径团聚体交换性氢的分配比例均以植茶53 a时较高，为17.97%~19.69%；>20~40 cm土层各粒径团聚体交换性氢的分配比例以植茶16 a时较高，为19.51%~22.77%，而各粒径团聚体交换性铝的分配比例则呈相反的趋势.研究显示，长期植茶会导致土壤酸化，随着植茶年限的延长，土壤pH逐渐降低，交换性氢、交换性铝和交换性酸含量均升高，不同粒径团聚体对交换性酸的保持能力存在明显差异. 

Effect of Tea Plantation Ages on Soil Acidification and Distribution of Exchangeable Acidity within Soil Aggregates

In order to determine the correlations between the acidity and exchangeable acidity of soil aggregates and the tea plantation ages, soil samples were obtained from tea plantations with different ages (16, 23, 31 and 53 a) and the distribution of exchangeable acidity within soil aggregates under different tea plantation was studied based on the method of field investigation and laboratory analysis. The results showed that: (1) Soil pH value gradually presented decreasing trends and the contents of exchangeable hydrogen, exchangeable aluminum and exchangeable acid showed an increasing trend along with rising ages of tea plantations. Among the four tea plantation ages, soil pH value in the 0-20 cm soil layer was significantly higher than that of >20-40 cm soil layer. It was an opposite tendency for the exchangeable hydrogen, exchangeable aluminum and exchangeable acidity with the decreasing particle sizes of soil aggregates, and the content of exchangeable hydrogen increased by 21.29% after the plantation age of 23 a. (2) The content of exchangeable hydrogen, exchangeable aluminum, and exchangeable acidity increased with the decreasing particle sizes of soil aggregates, and the content of exchangeable hydrogen, exchangeable aluminum, and exchangeable acidity increased with rising ages of tea plantations. (3) With the decrease in size of soil aggregates, the ratios of exchangeable hydrogen increased by 18.41%-22.77%, while the ratios of exchangeable aluminum presented opposite trends. Higher values of the exchangeable hydrogen ratio were found in the tea plantations with ages of 53 a (17.97%-19.69%) in the 0-20 cm soil layer, while higher values of the exchangeable hydrogen ratio were found in tea plantation age of 16 a (19.51%-22.77%) in the >20-40 cm soil layer. However, the ratios of exchangeable aluminum presented opposite trends. Along with rising ages of tea plantations, soil pH value presented decreasing trends, while it was an increased tendency in exchangeable hydrogen, exchangeable aluminum, and exchangeable acidity. The retention ability of exchangeable acid was obviously different in all particle sizes of aggregates.