21. Group of Soil Series No.21

This group includes somewhat poorly drained, medium-textured soils that are commonly stratified with sand and silt layer that occur mostly on flood plain or alluvial plain. They are moderately low fertility. Soil reaction is strong to medium acid. Soils in this group are Petchaburi (Pb) and Saphaya (Sa) series.                 Most areas are covered with paddy rice in rainy season and cash crops in dry season if water supply is available.

Problems : Sandy and silty layer soils induce lack of water, but overland flow or water logging in rainy season in some places.

Management for rice : Leveling and raised bed to preserve water then 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 Sesbinia rostrata or S. speciosa and 16-16-8 chemical fertilizer or LDD liquid organic fertilizer. Top dressing with 16-16-0 chemical fertilizer, 35-45 days after rice transplanting. Farm ponds are recommended to preserve water to be used in dry season or second rice crop. If vegetables or legume will be planted, furrows would be constructed with application of 2-3 ton/rai compose fertilizer or animal manure with chemical or liquid LDD fertilizer.

Management for vegetable or orchard : Raised bed to 6-8 meters wide with 1.0-1.5 meters drainage canal. Raised bed around the areas then apply 2-3 ton/rai compose fertilizer or animal manure with chemical fertilizer or LDD liquid organic fertilizer. Apply 20-25 kg of compose fertilizer or animal manure into 50*50*50 meters pit to grow orchard. Apply compose fertilizer 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 to preserve water to be used in dry season.