Clay mineralogy of soils from upper north Thailand

A total of about 80 soil samples from 20 profiles distributed in Upper North Thailand were examined for the composition of the clay mineralogy. The soils from upland areas consisted of principally kaolinite and those from lowland areas (paddy fields) showed a mixed mineralogy characterized by the presence of kaolinite or illite, or both. Such characteristics of the clay mineralogy were almost the same as those reported so far, and the results are summarized in the APPENDIX. In this report the description deals with which showed some “exceptional” features of clay mineralogical compositions as follows: Mae Suya soil (a Typic Haplustult) which showed randomly mixed layers containing large amounts of illite and illite-vermiculite in addition to kaolinite; Mae Lana Jobo soil (an Oxic Paleustult) which was dominated by gibbsite with considerable amounts of vermiculite and kaolinite; and Khok Yai soil (an Oxic Haplustalf) which was characterized by the presence of mixed layers with large amounts of illite and illite-vermiculite coexisting with kaolinite, halloysite, and gibbsite. Such characteristics of the clay mineralogical composition were very different from those of common upland soils of Thailand.