[目的]比较不同亚纲变性土之间线性膨胀系数的差异，并通过对比不同亚纲土壤物理属性，解释产生差异的内在机制。[方法]新疆北部地区（简称北疆地区）是夏旱变性土（含变性土壤）主要分布区，本研究调查了具有变性特征的14个土壤剖面，并搜集了我国其他12个省市140个变性土剖面相关数据，分析了不同亚纲变性土的线性膨胀系数（coefficient of linear extensibility，COLE）、黏粒和蒙皂石含量及其相关关系。[结果]北疆地区夏旱变性土（含变性土壤）的COLE、黏粒和蒙皂石含量在5个亚纲中最低，其土壤膨胀收缩特性主要受伊利石一蒙皂石混合型矿物组成和混层比的影响，而其他4个亚纲较夏旱变性土（含变性土壤）具有更明显的变性特征。潮湿变性土、湿润变性土和夏旱变性土（含变性土壤）0-100cm土层的黏粒和蒙皂石含量大于0-30cm土层，而干润变性土0～30cm土层含量高于0～100cm土层。寒变性土随着剖面深度的增加，黏粒和蒙皂石含量无明显变化。潮湿变性土0～100cm土层蒙皂石含量显著高于干润变性土和夏旱变性土（含变性土壤），且0～100cm土层的COLE值也显著高于夏旱变性土（含变性土壤），5个亚纲表层土壤的COLE差异不显著。随着黏粒含量的增加，干润变性土蒙皂石含量和潮湿变性土COLE随之增大，表层蒙皂石含量对COLE影响更大。[结论]北疆地区蒙皂石和伊利石一蒙皂石混合型矿物组成是土壤变性的内在影响因素，变性土中蒙皂石与黏粒呈线性相关，黏土矿物组成对表层土壤膨胀收缩有决定性作用。
[ Objectives ] To explore the dominant factors affecting vertic characteristics of vertic soils, clay content and mineral compo- sition were compared among suborders of vertisols. [ Methods ] Northern Xinjiang is the main distribution area of Xererts （ including vertic soils）, and we analyzed 14 soil pedons of vertic soils from northern Xinjiang, and collected data of 140 vertic soil profiles from 12 provinces of China. Data of coefficient of linear extensibility （ COLE）, clay content and smectite were analyzed. [ Results ] COLE, contents of clay and smectite of Xererts（ including vertic soils）were the lowest in the five suborders and the swelling and shrinking characteristics of soils in northern Xinjiang were mainly affected by the higher illite-smectite mixing layer content. The other four suborders had more obvious vertic properties than Xererts（ including vertic soils）. Contents of clay and smectite of Aquerts, Underts and Xererts （including vertic soils）at 0-100 cm were higher than those at 0-30 cm,while the case for Usterts was just in contrary. With increasing depth, clay and smectite did not change significantly for Cryerts. Smectite content of Aquerts was significantly higher than those of Usterts and Xererts （including vertic soils）, and COLE value at 0-100 cm soil layer was significantly higher than that of Xererts（ including vertic soils ）. However, COLE values of the five suborders were not significantly different at surface. With increasing of COLE of Aquerts, clay content and smectite content of Usterts increased and the change of surface smectite was linearly related with COLE. [ Conclusions ] Illite-smectite mixing layer content and smectite content of Xererts （ including vertic soils） in northern Xinjiang were the intrinsic factors of soil vertic characteristics, while smectite content was closely related to clay content. Clay mineral composition plays a decisive role in controlling swelling and shrinking of surface＇s vertisols.
Journal of Nanjing Agricultural University