Sandy soils of Cambodia
Seng, V., Bell, R.W., White, P.F., Schoknecht, N., Hin, S. and Vance, W. (2007) Sandy soils of Cambodia. In: Management of Tropical Sandy Soils for Sustainable Agriculture: Symposium on the Management of Tropical Sandy Soils, 27th November – 2nd December, 2005, Khon Kaen, Thailand .
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Siliceous sedimentary formations underlie much of Cambodia, consequently there is a propensity for sandy surface soils. Only the soils fringing the Tonle Sap lake, those of the alluvial plains along the major rivers (especially the Mekong), and soils developed on basalt deviate from the characteristic of sandy soils. Substantial areas of sandy, high permeability soils are used for lowland rainfed rice production. Due to their inherent high hydraulic conductivities, standing water in rice fields of the deep sandy soils drains rapidly after rainfall predisposing rice crops to drought and high rates of nutrient leaching. However, loss of soil water saturation may limit rice yield by inhibiting nutrient uptake more often than drought, per se. Prospects for growing field crops in sandy lowland soils are contingent on the amounts and reliability of early wet season rainfall or on amounts of stored water after harvesting rice. Apart from drought, waterlogging and inundation are significant water-related hazards that influence the growing of field crops in lowland soils. In addition, soil fertility constraints in the early wet season and dry season will likely differ from those encountered by rice due in part to the different soil water regime they encounter. In particular soil acidity, low nutrient status, hardsetting and shallow rooting depth have been identified as significant constraints for field crops. Vast areas of sandy upland soils occur in Cambodia but are only poorly described. Low soil fertility is likely to limit upland farming systems on the sandy uplands and erosion is a concern for their sustainable use. There is a need to hasten the pace of research and resource assessment of these uplands so that land suitability assessment and sustainable farming systems are available to guide the expansion of agriculture in these areas.
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