SOME PHYSICAL PROPERTIES OF TWO SOILS FROM THE BANGKOK BASIN

R. F. ALLBROOK*

ABSTRACT: Two soil profiles from the padi growing area of the Bangkok basin, Thailanti are described and classified as fine clayey non acid mixed isohyperthermic vertic tropaquepts. The lack of change in pH on drying and the sulfur analysis supports the non acid nature of the soils. Clay mineralogy was not done so mineralogy is only deduced. Shrinkage is significant and the COLE values are high hence the vertic great subgroup. Particle size analysis suggests that the soils are bisequent. A shrinkage line was plotted having a slope of one. This implies that stable pores do not exist in the size range 0.2mm- 30mm, possibly due to the low sand content. The soils have a low air filled porosity. The majority of pores are in the micropore range thus a low hydraulic conductivity would be expected. Surface water flooding, a desirable feature for padi growing, could therefore be maintained despite a relatively deep water table.

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Earth Sciences, University of Waikato, Hamilton New Zealand. Research completed at Faculty of Environment and Resource Studies, Mahidol University, Salaya, Nakornpathom 73170, Thailand.
*Corresponding author.

Received May 26, 1993