Use of lake bottom sediment as physical amendments for sandy soils in Songkla lake basin
2006
Charlchai Tanavud(Prince of Songkla University. Hat Yai Campus, Songkhla (Thailand). Faculty of Natural Resources. Department of Earth Science) | Chao Yongchalermchai(Prince of Songkla University. Hat Yai Campus, Songkhla (Thailand). Faculty of Natural Resources. Department of Earth Science) | Omthip Densriserekul(Prince of Songkla University. Hat Yai Campus, Songkhla (Thailand). Faculty of Natural Resources. Department of Earth Science)
Characterization of physical and chemical properties of the sand and sediment led to the conclusion that both materials possess physical and chemical limitations to plant growth. Low water holding capacity was the major physical factor limiting the establishment of vegetation on the sand, whereas poor aeration associated with low saturated hydraulic conductivity was the main physical constraint in the sediment. These observed limitations are primarily related to their particle size distribution, which varies markedly between the two fractions. Hence, a possible solution to these physical constraints is to manipulate the particle size distribution by mixing the sand and the sediment. In this study, a series of sand-sediment mixtures, containing 0, 20, 40, 60, 80 and 100 percent sediment by weight, were prepared by mixing the sand and sediment in a blender and subsequently packed by subjecting to three wetting and drying cycles. Thereafter the optimum ratio of sand to sediment was determined from the relevant physical properties of the mixtures, particularly plant available water capacity and oxygen diffusion rate. Result revealed that potentially a mixture of 80 percent sand and 20 percent sediment appears to pose fewer limitations to plant growth than sand, sediment or any other mixtures of the two. The use of less than 20 percent sediment in the mixture would result in reduced plant available water capacity, which can be a limiting factor to plant growth, while greater than 20 percent sediment tends to increase the probability of inadequate aeration, particularly under high rainfall conditions. An assessment of the response of plants to the physical properties of the sand-sediment mixtures under field conditions remains to be done, but the outlook for improving marginally productive sandy soils and solving sediment disposal problems in Songkla Lake Basin appears promising.
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