An assessment of the soil-conditioning capacity of gums exuded by some trees in sierra leone: I. hydraulic conductivity measurements
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Chemistry Department, Fourah Bay College, University of Sierra Leone, Freetown, Sierra Leone
Int. Agrophys. 1995, 9(1): 55–65
Gums exuded by two trees viz., Anacardium occidentale and Parkia bicolor growing widely in Sierra Leone have each been applied in various concentrations to two local soils with poor structure. Changes in the value of the saturated hydraulic conductivity (K) of each soil sample, brought about by the application of the gums, have been used as the index for determining soil conditioning effect; the K of a carefully selected loamy soil (untreated with conditioner) is used as reference. Poly(vinyl alcohol) (PVA) was also applied in identical concentrations to the same soil samples; this permitted a comparison to be made between the effectiveness of this established synthetic soil conditioner and the plant gums. The results show that the plant gums as well as the PVA exhibited positive soil-conditioning effect by altering the K of the soils with poor structure to the value obtained for the loamy soil. It was further observed that prior treatment of the soil samples with CaCl2 enhanced soil-conditioning capacity. In almost all cases the relative effectiveness of the conditioners was in the order: gum from P. bicolor > gum from A. occidentale > PVA. The results are explained in terms of factors known to influence soil-polymer interactions.