This group of soils includes typical acid surface soils that commonly contain high salt content at the soil surface. Most areas have been left abandoned and salt-tolerant plants are commonly grown. Soils in this group is Cha-am (Ca) series.

Problems: Massive structure, strong acid with accumulation of salt, difficult to be prepared, lack of water in dry season and water logging in rainy season.

Management for rice: Prepare and spread 1,000-2,000 kg/rai lime into moist soils, logging water into soils to leach acid and salt. Mix crop residue with soils and leave for 3-4 weeks or apply 50-70 days green manure with LDD organic fertilizer or 16-20-0 chemical fertilizer, 35-45 days after transplanting.Farm ponds are recommended to preserve water to be used in dry season and to leach and control salt in the field.

Management for vegetable or orchard: Raised bed to 6-8 meters wide with 1.0-1.5 meters width and 0.5-1.0 meters depth drainage canal. Spread 1,000-2,000 kg/rai lime into the top soil beds and logging water into soils to leach acid and salt. Soils improvement with 2-3 ton/rai compose fertilizer oranimal manure and chemical or LDD organic fertilizer. Mix 20-35 kg. compose fertilizer or animal manure with 7 kg of lime in 50*50*50 cm. pit for growing orchard. Apply chemical or LDD liquid organic fertilizer with compose fertilizer and animal manure at vegetative growth, before and after harvest. Apply spread of 1,000-2,000 kg/rai lime into acid sulfate soils.