Rehabilitation of gypsum-mined lands in the Indian Desert

The economic importance of mining in the Indian Desert is second only, to a griculture. Land disturbed by, mining, however, has only recently, been the focus of rehabilitation efforts. This research assesses the success of reh abilitation plans used to revegetate gypsum mine spoils within the environm ental constraints of the northwest Indian hot-desert ecosystem. The rehabil itation plan first examined both mined and unmined areas and established as sessments of existing vegetative cover and the quality, of native soils and mine spoils. Tests were made on the effect of the use, and conservation, o f available water through rainwater harvesting, amendment application (for physical and chemical spoil modification), plant establishment protocols, a nd the selection of appropriate germ plasm. Our results show that the resul ting vegetative cover is capable of perpetuating itself under natural condi tions while concurrently, meeting the needs of farmers. Although the mine s poils are deficient in organic matter and phosphorus, they, possess adequat e amounts of all other nutrients. Total boron concentrations (> 5.0 mg kg(- 1)) in both the topsoil and mine spoil indicate potentially phytotoxie cond itions. Electrical conductance of mine spoil is 6-10 times higher than for topsoil with a near-neutral pH. Populations of spoil fungi, Azotobactor, an d nitrifying bacteria are low. The soil moisture storage in rainwater harve sting plots increased by 8% over the control and 48% over the unmined area. As a result of rehabilitation efforts, mine spoils show a steady, buildup in organic carbon, and P and K due to the decomposition of farmyard manure and the contribution of nitrogen fixation by, the established leguminous pl ant species. The rehabilitation protocol used at the site appears to have b een successful. Following revegetation of the area with a mixture of trees, shrubs, and grasses, native unplanted species have become established. Spe cies diversity,, measured in terms of species richness, increased after one year and then gradually, declined over time; the decline was the result of the loss of annual species. The stud), not only, develops methods of gypsu m mine land rehabilitation but also helps in understanding processes of reh abilitation success in arid regions and emphasizes the importance Of long-t erm monitoring of rehabilitation success.