EFFECTS OF DISPERSIBLE SOIL CLAY AND ALGAE ON SEEPAGE PREVENTION FROMSMALL DAMS

A field experiment was conducted on a red-brown earth (Natrixeralf) to find the effectiveness of spontaneously dispersed clay from sodic soi ls and mechanically dispersed clay (by puddling) from calcic and sodic soils in reducing the seepage loss of water from a series of small da ms (pits). The effect of inoculating algae in the pits on reducing see page was also investigated. A plastic lined pit was used for water bal ance control to measure incoming rainfall and evaporative loss. The re sults showed the effectiveness of dispersed soil clay in sealing the s urface 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 s odic soils, The mechanically dispersed clay from calcic soils were les s effective in sealing because of the deposition of flocculated materi als 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) producti on was only small.