Effects of dispersible soil clay and algae on seepage prevention from small dams

Abstract

A field experiment was conducted on a red-brown earth (Natrixeralf) to find the effectiveness of spontaneously dispersed clay from sodic soils and mechanically dispersed clay (by puddling) from calcic and sodic soils in reducing the seepage loss of water from a series of small dams (pits). The effect of inoculating algae in the pits on reducing seepage was also investigated. A plastic lined pit was used for water balance control to measure incoming rainfall and evaporative loss. The results showed the effectiveness of dispersed soil clay in sealing the surface soil materials in the banks and beds of the pits. The dispersed clays from sodic soils were very effective in reducing the seepage to zero. When the clay concentration was above 8 g L−1 the sealing was complete, irrespective of spontaneous or mechanical dispersion from sodic soils. The mechanically dispersed clay from calcic soils were less effective in sealing because of the deposition of flocculated materials in the pore systems formed domains and generated microporosity. In calcic pits, the inoculation of algae reduced the seepage by 13 to 23% and increase in biopolymer (chlorophyll and polysaccharide) production was only small.