Problem hydromorphic soils in North-east Thailand. 1. Environment and soil morphology

摘要: The Roi Et soil, a Gleyic Acrisol (FAO, 1974) is one of the main soils on extensive seasonally wet, low terrace in north-east Thailand. soil looks poor and produces traditionally yields paddy rice crop/year. With fertilizers dry-season irrigation, problems water-logging, surface salinity acidity caused germination both dryland crops. X-ray stereo radiographs, macro- micromorphological data indicate that processes have taken place this include perforation homogenization by roots fauna; iron mobilization redistribution; clay translocation; alteration formation secondary silica; slaking alternated with ploughing. translocated appears to be fossil clay. Two stages under (seasonally) wet conditions are indicated, later one, alteration, continuing at present. has considerable macroporosity, due worms termites, mainly subsoil. ploughpan deep subsoil porosity. (Abstract retrieved from CAB Abstracts CABI’s permission)