... 7 0-8 0%. Differences in regional rainfall have resulted in the identification of 3 major agri-ecological zones: • Nam-Ngai (Quang Nam & Quang Ngai): 200 0-2 600 mm ; • Binh–Phu (Binh Dinh & ... sustainable management of sandy soils. Proceedings of 'Management of Tropical Sandy Soils for Sustainable Agriculture', pp 35 7-3 61, 27 Nov-2 Dec 2005, Khon Kaen Thailand. FAO: Bangkok. ... tropical monsoon climate with an annual temperature of around 24oC-27oC on average (minimum 20oC-21oC and maximum 31oC-32oC). Total heat accumulation per annum is 8,000oC– 9,500oC,...