Abstract: In order to understand the change rule of exchangeable Ca and Mg content under different soil texture and tree-age condition, this paper choose sandy and loam 2 kinds of walnut tree orchard, one in primary fruit period and the other in full fruit period, and tested the exchangeable Ca and Mg contents in soil. The results showed that there were remarkable differences in contents of exchangeable Ca and Mg in different soil texture. Relatively speaking, the loam had strong adsorption and immobilization capacity of Ca2+, and also high Ca2+ content. There were significant differences in contents of exchangeable Ca and Mg between loam and snay soil（P＜0.05）. Under loam condition, there were also big differences in soil exchangeable Ca and Mg contents between 2 different tree-ages. Soil types had certain effect on the change of soil exchangeable Ca/Mg. Exchangeable Ca and Mg showed significant negative correlation between loam and sandy soil. While under the same soil condition, Ca and Mg showed significant positive correlation. The ratio of exchangeable Ca/Mg was negatively correlated with the content of exchangeable Mg.

Key words: soil texture, tree-ages, exchangeable calcium and magnesium

摘要： 为了解不同土壤质地和树龄条件下土壤中交换性Ca、Mg含量的变化规律，选择砂土、壤土两个类型的初果期、盛果期两种树龄核桃园，测定土壤交换性Ca、Mg含量。结果表明，不同土质中交换性Ca、Mg含量差异较大，壤土相对来说吸附、固持Ca2+能力比较强，含量较高，与砂土质地土壤中交换性Ca、Mg含量的差异均达到显著水平（P＜0.05）。壤土条件下不同树龄之间土壤交换性Ca、Mg含量也有较大的差异。土壤类型对土壤交换性Ca/Mg大小的变化有一定的影响。壤土与砂土之间Ca、Mg均呈现显著负相关，而同一土壤条件下Ca、Mg之间呈显著正相关。交换性Ca/Mg与交换性Mg含量呈显著负相关。

关键词: 土壤质地, 树龄, 交换性钙镁