Properties and agricultural potential of skeletal soils in southern Thailand

Study on properties and agricultural potential of skeletal soils in Southern Thailand placed a major emphasis on representative skeletal soils that can be found in large extent, moderate extent and limited extent in the region. Study method included field investigation and pedon analysis of the representative soil and collecting soil samples from their genetic horizones, and laboratory analysis on their physical and chemical properties to evaluate their vital properties and their agricultural potential. Eight representative soil series included Chumphon series, Khao Khat series, Nong Khla series, Phato series, Ranong series, Phayom Ngam series, Sawi series and Yi-ngo series. Results of the study revealed that most of them are upland soils mainly occupying undulating and rolling terrains with a major slope tange of 3-8 percent. Most of them are deep to very deep, highly leached, well developed Ultisols. The skeletal materials in these soils vary but the ones that can be found frequently are ironstone nodules. Their basic fertility status is generally poor and problem on available phosphorus in most soils exists. Their high extractable acidity is also a vital adversary property that can affect their exchange properties markedly whereas the presence of skeletal materials in the soils does not appear to pose any serious problem on their uses and management. These soils are not suited for paddy rice but they are moderately suited for upland field crops and livestock pasture, and well suited for tree crops including fruit trees with different degrees of problem on topography and the presence of skeletal materials. Since these soils have been used mainly for rubber and fruit tree production, land use problem on them can be coped with quite well by the use of existing agricultural technologies. Therefore, sustainability in their use, at present, is somewhat achieved.