11. Group Soil Series No.11

This group consists of typical acid sulfate soils that are very strongly acidic ( plot > 4.5 at the surface ). This group of soil occur mainly on the coastal plain of brackish water deposit. Most areas are used for cultivation of paddy rice but liming is necessary. Soils in this group are Don muang (Don), Sena (Se) and Tanya Buri (Tan) series.

Problems : Massive structure (crack when dry and stick when moist), very strong acid within 50-100 cm. depth, fixing plant nutrients and induce toxicity, lack of fresh water (acidity), water logging in rainy season.

Management for rice :Prepare and spread 500-1,000 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 ecommended to preserve water to be used in dry season or for second rice.

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 500-1,000 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 or animal manure and chemical or LDD organic fertilizer. Mix 20-35 kg. compose fertilizer or animalmanure 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 harvesting. Apply 500-1,000 kg/rai broadcast lime into acid sulfate soils.