Browns turned to greens
NEW Delhi's Bhatti and Asola mines, abandoned after endless quarrying, were homes to hectares of extensively degraded gullies and ravines devoid of vegetation. Mining had threatened the hydrological balance as well as reclamation of the soil in this area.
A team of botanists from Delhi University led by C R Babu, director of the Centre for Environment Management of Degraded Ecosystems, has recently pioneered the revegetation of these lands. He has made one ha of this area greener and also promises to restore the original vegetation that existed more than a hundred years ago. Babu explained that the team's first step to revegetate the area was to develop a microbial community which could survive in such an environment. Following that, an effective innoculation technology was undertaken. The bacterium was then immobilised in a gel made of water and nutrients. To associate the microbe with the seed, the seed was encapsulated with the immobilised bacterium containing gel. This resulted in an artificial seed with microbes to fix nitrogen. The final products were beads containing these seeds, which were then sprayed.
Babu intends to restore the indigenous vegetation ideal for wildlife. The steep slopes of the terrain have been revegetated with perennial grasses as they prevent runoff of surface water. Acacia, Butea, Albizia and Cassia plants also co-exist. Their roots help in restoring the porosity of rocks clogged by silt. Babu, along with his colleagues, selected a large number of species which were native to the Aravallis and were part of the original vegetation. The team collected 20 different legumes, eight species of Acacia, 50 grasses and 50 microbes associated with these legumes and grasses. These microbes accelerate establishment of the vegetation as some of these fix nitrogen, some solubilise insoluble nutrients, some detoxify nutrients and some make nutrients easily available to higher plants.
Babu was the first to devise this ecological restoration technology used in Bhatti and Asola mine region. These two areas are of importance to the capital, since they are located in the watershed region. They constitute the catchment area as a bulk of the rainwater enters this area. Explaining the technology Babu says that under harsh conditions, a vegetation cover which provides organic matter is the best bet for weathering rocks and stabilising the soil. Legumes and grasses, which are drought-resistent and secrete acids to weather rocks, possess such charcteristics. They can produce readily decomposable biomass and fix up their own nitrogen. This is the reason the team collected legumes, grasses and microbes.
Within five years, the entire rocky terrain is expected to be transformed into a richer, greener area. The best thing about this technology is that it cost just about Rs 10,000 to revegetate one ha of land. For revegetating the same area, the forest department is known to spend lakhs.
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