This group of soils is well drained, dark colored heavy clay that occupies in karst topography and basaltic terrain in ustic moisture regime . Soil fertility is commonly moderate. Soil reaction is neutral to moderately alkaline. Soils in this group are Chai Badan (Cd), Dong Lan (Dl) Lop Buri (Lb), Nam Len (Nal) and Wang Chompoo (Wc) series.
                  Upland and tree crops are grown in this group. Crop production is relatively high in managed soils.

Problems: Very heavy clay that crack and lack of water in dry condition and stick in moist condition.

Management for upland crops or vegetables: Application of 2-3 ton/rai compose fertilizer or animal manure or mixed green manure (broadcast 8-10 kg/rai sword bean , 6-8 kg/rai cow pea or 4-6 kg/rai Crotalaria juncia) and mix with soils before flowering. Chemical or liquid LDD fertilizer will also be applied according to recommendation . Farm ponds are recommended to preserve water to be used in dry season.

Management for orchard: Soil preparation in 50*50*50 pit is to mix 20-35 kg compose fertilizer or animal manure. Conserve the soils by cover crops, mulching, and contour or fencing the tree with vetiver. Application of compose fertilizer or animal manure with chemical or liquid LDD fertilizer at vegetative growth, before and after harvesting. Farm ponds are recommended to preserve water to be used in dry season.