Rapid expansion of cropping is occurring in Cambodia outside of the areas traditionally used for lowland rice. Soils and landscapes in these areas are poorly described at present, hampering efforts to develop sustainable soils management and crop production systems. In the present project, soils and landscapes in Tram Kak district Takeo province were investigated by a semi-detailed soil survey. A soil-landscape map was developed for the district in which 9 units were recognised. The main soil-landscape units in order of their likely capability for non-rice crops were: Prey Khmer, Prateah Lang, and Bakan Soil groups. Most of the occurrence of the deep sands of the Prey Khmer Soil group was in close proximity to the quartzite ridge on the western border of Tramkak with smaller occurrences in the southeast of the district overlying a sandstone rise, and in the north of the district as reworked alluvial sediments from a small river. Deep sandy soils belonging to Prey Khmer Soil group, which occupied about 34 % of the district, were low in most plant available nutrients and acidic with Al saturation up to 80 %. However, not all the profiles had excessive levels of exchangeable Al. In total, the Prateah Lang Soil group occupies about 60 % of Tram Kak district including both clay and loamy sub-soil phases, although the distribution of each phase was not defined. The clay sub-soil phase was strongly acid in the sub-soil whereas two out of three profiles of the loamy sub-soil phase were strongly alkaline in the sub-soil. However, all Prateah Lang soils had extremely low exchangeable K, and low levels of N, P, S and micronutrients Cu, Zn and B. By contrast extractable Mn levels were high in the surface layers of most Prateah Lang profiles. For the production of crops such as maize, mung bean, soybean and peanut, both farmers’ assessment and the yield of field trials showed lower productivity on the Prateah Lang soils, presumably due to waterlogging and low water storage constraints compared to Prey Khmer soils
