Wisai Tai (วิสัยใต้) is a subdistrict of Sawi in Chumphon. Chumphon Horticultural Research Centre, part of the Department of Agriculture, is based in Village 2 along Highway 41. It is a specific research institution within the wider tambon.
Agricultural water management is another documented local theme. The Royal Development Projects Board records the Ban Phraek Haeng weir and water-distribution project serving farming communities in Villages 6, 7 and 9. These references help identify the tambon's agricultural setting without assigning the research site's soil or drainage conditions to every village. Institutional visits require the centre's own arrangements.
