This soil group consists mainly of poorly drained and fine-textured that commonly occur on low-lying terrain of brackish water deposits, former tidal flat or flood plain. This soil group is strong acidic and moderate fertility. Soils in this group are Ayutthaya (Ay), Bang Khen (Bn), Bang Nam Prieo (Bp), Maha Phot (Ma) and Tha Kwang (Tq)

Problems: Because of strong acid, the soils then fix plant nutrients and toxicity will be released. Soil texture is massive and cracking when dry and difficult to be prepared. Lack of fresh water in dry season but water is logging in rainy season.

Management for rice: Prepare and mix crop residue into moist soils and leave for 3-4 weeks.If managing by green manure, it should be the mixture of 4-6 Kg/rai of 50-70 days Sesbania rostrata and 16-20-0 chemical fertilizer or LDD liquid organic fertilizer in the soils and leave for 1-2 weeks.Reduce acidity by application of broadcast 500 kg/rai lime. Top dressing again 35-40 days after transplanting. Farm ponds are recommended
to preserve water to be used in dry season or second rice crop or short season crops after first rice. After harvesting second crop, 2-3 ton/rai compose or animal manure with chemical fertilizer or LDD liquid organic fertilizer should be applied.

Management for vegetable or orchard: Raised bed to 6-8 meters wide with 1.0-1.5 meters drainage canal. Reduce acidity by application of broadcast 500 kg/rai lime. Apply 2-3 ton/rai compose fertilizer or animal manure with chemical fertilizer or LDD liquid organic fertilizer. Apply 20-35 kg of compose fertilizer or animal manure and 5 kg of lime into 50*50*50 meters pit to grow orchard. Apply compose or animal manure with chemical fertilizer or LDD liquid organic fertilizer at vegetative growth, before and after harvesting. Farm ponds and water management are recommended. Broadcast of 500 kg/rai lime will be applied again if acidity is increased.