Effects of clay mineralogy on soil fertility of the arable Iand in the tropics.

从亚洲（泰国、马来西亚、印度、柬埔寨、斯里兰卡、孟加拉国、菲律宾、印度尼西亚、越南、缅甸和东马来西亚）、南美洲（巴拉圭、巴西和哥伦比亚）和非洲（尼日利亚、科特迪瓦、塞拉利昂、利比里亚、扎伊尔和卢旺达）的可耕地中收集土壤样本，并对其进行矿物学和理化特征分析。对上述土壤数据进行多元统计分析（主成分分析），提取控制土壤肥力的3个因子，即固有潜能、有机质状态和速效磷状态，从而定量评价土壤肥力。对这些样品应用了同样的程序，并确定了两个因素，即岩性和风化状态，并证明了它们对表征土壤材料的性质是有用的。所有这些因素都与每种土壤的优势粘土矿物类型密切相关。

Soil samples were collected from arable land in Asia (Thailand, Malaysia, India, Cambodia, Sri Lanka, Bangladesh, Philippines, Indonesia, Vietnam, Burma and East Malaysia), South America (Parguay, Brazil and Columbia) and Africa (Nigeria, Ivory Coast, Sierra Leone, Liberia, Zaire and Rwanda) and analyzed for mineralogical and physico-chemical characterization.Multivariate statistical analysis (principal component analysis) was applied to the above mentioned soils data and three factors controlling soil fertility, i.e.inherent potentiality, organic matter status and available phosphorus status were extracted, each of these enabling quantitative soil evaluation. The same procedure was applied to those samples and two factors, i.e.Iithology and weathering status, were identified and proved to be useful for characterizing the nature of soil materials. All such factors were closely related to the type of predominating clay minerals of each soil.