Properties, Environment and Fertility Capability of Sandy Soils in Northeast Plateau, Thailand

Abstract

A study on properties, environment and fertility capability of sandy soils in Northeast Plateau, Thailand was carried out using nine soil areas as study sites. Field study included pedon analysis and soil environment observation and sampling of soils for laboratory analysis. Laboratory study consisted of physical, chemical, mineralogical and micromorphological analyses of soil samples by standard methods and soil fertility capability determination using a software computer program. Results of the study revealed that these soils comprise sandy Entisols, sandy Alfisols, sandy Ultisols and coarse-loamy Ultisols on mainly sandy alluvium with generally undulating to flat surface landscape. With the strong influence of sandy parent materials and tropical savanna climate most of the soils even with different profile features show common properties of being acidic, having low natural fertility status and with poor exchange properties. Nevertheless, the soil system still favor cation exchange and their poor fertility can be considered most adversary to crop practices. Fertility capability units of these soils include Sdaekp, Sdhekp and SLdhekp for the upland soils, and Lgaekp and Lghekp for the lowland ones indicating less serious problem for the lowland soils. Major common constraints for their overall fertility capability are their poor exchange properties (e), low available potassium (k) and phosphorus (p). For the upland sandy soils, in addition to their poor fertility status, the soils have low water holding capacity and with rapid infiltration rate (S) making them very susceptible to moisture deficiency. The lowland soils, however, have good moisture regime for paddy rice with a strong potential for denitrification in anaerobic condition of subsoils (g) during cropping season. General recommendations for management of these soils include split application of complete fertilizer, surface organic matter management, low rate liming and monitoring of potassium availability in cropping practices.