Reducing water seepage from earthen ponds

Small earthen reservoirs have proved to be a promising answer to the problem of storing water on arid-land farms. However, these little ponds or tanks can lose very large amounts of water through seepage. To reduce such losses is a vital need. In the present experiments, chemical, physical, and biological methods for reducing seepage were evaluated in small ponds created in a permeable, calcareous, silt-loam soil. The chemical method involved treating the top 10 cm of soil with sodium carbonate (Na2CO3). The physical method involved compacting the soil. And the biological method (the so-called ''bio-plastic sandwich'') consisted of successive layers of soil, manure, vegetative material and soil. The chemical treatment proved less efficient than the other two. Compared to the untreated soil, the physical and biological methods reduced the mean cumulative seepage rates (measured 350 days after the initial wetting) by 72% and 67%, respectively. Both of these treatments seem to be cost-effective and ready to be applied to the farm ponds of Pakistan.