Ecological approach to waste land development.
The use of an ecological index (EI=P×D/Tr×EPT, where P=annual precipitation, D=number of rainy days per annum, Tr=range of maximum temperature averages, and EPT=potential evapotranspiration) to characterize the potential of a degraded site for afforestation is described, and on this basis a case study presented of a strategy for planting highly eroded areas in Bagalkot Division, Bijapur District, Karnataka. Previous planting in the area has involved trench mound planting of Eucalyptus, mechanized planting of Hardwickia binata, and (in better areas) neem [Azadirachta indica]. This has given unsatisfactory results. The new strategy (formulated on the basis of the calculated EI) suggested that the area was only suitable for grassland development, and planting of a few local and hardy species. Methods of soil working and planting are described. These involved planting tree seedlings in pits with shoulder trenches, formation of micro-catchments for water harvesting, planting of the associated mounds with Agave and Prosopis (seeds), and planting the spaces between plants with fodder plants. Costs are outlined. Data are tabulated on the survival and growth of 10 tree species planted in the 1989 rains. Survival in April 1990 was 96%, and casualties (35%) were replaced in the 1991 rains, from which a final survival of 93-100% was obtained. Best growth was by Albizia lebbeck, Azadirachta indica and Dalbergia sissoo. The other tree species planted were Emblica officinalis [Phyllanthus emblica], Ficus, Inga dulcis, Hardwickia binata, Pongamia pinnata, Tamarindus indica and Zizyphus jujuba [Ziziphus mauritiana]. The planted area remained green most of the time, and water yield in a well adjoining the plantation increased.