SR-3/99-2000 : Bio-Drainage

Abstract

The problem of soil degradation is widespread in India, affecting about 1,880 lakh hectares or 57 per cent of the total area of the country. Of this, 1,620 lakh hectares are affected by soil erosion and in situ degradation i.e. waterlogging, salinisation, and nutrient depletion affect 250 lakh hectares. The area affected by soil degradation in 1947 was probably about 1,100 lakh hectares. The cumulative effects of degradation over time may lead to an economic loss of 11-26 per cent of annual agricultural output. The losses due to erosion is around 1,180 lakh hectares or 36 percent of the total area of the country uneconomical to cultivate because of a significant loss in productivity, while a further 150 lakh hectares is unmanageable and uneconomical to use.

With the increase in water resources for agricultural uses, a major portion of the useful agricultural land in irrigation commands have either become unproductive or barren due to waterlogging, increased salinity or sodicity. In recent few decades this problem has adversely affected agricultural yield. The problem has occurred due to over irrigation, inadequate surface drainage, obstruction of natural surface/subsurface drainage, obliteration of a natural drainage, seepage from canals and reservoirs, rising of water table and the poor water management practices. In the report waterlogging and soil salinity both on global and Indian context have been described.

To solve the twin problems of waterlogging and salinity in the irrigated command area various drainage or traditional reclamation measures viz. controlling the intensity of Irrigation, providing drainage system, lining, improving natural drainage, preventing seepage or adopting modern technology of application of water etc. are considered. It is Learnt that the traditional approaches are not only difficult, but expensive too. Therefore the methods of bio-drainage, which is an agronomic solution provides natural means of drainage for excess water of the area through trees and plants, capable of transpiring more water like water pumps. The method is sustainable, economically beneficial and ecologically safe. In this th e plants like Eucalyptus etc. having capability of withdrawing a lage amount of water and salt serve to control waterlogging and soil salinity both. The works carried out Rajasthan canal and area in our country are encouraging. Many species of exotic plant 'eucalyptus', are not only capable of surviving in adverse conditions of waterlogging and soil salinity, their high degree of evapotranspiration from their canopy crown makes them more suitable to combat or to reduce the problems considerably. The cost-effective plantation and high bio-mass production, utility in paper and pulp production, in cosmetics and pharmaceuticals are some of the additional benefits. The improvement in soil, water and environmental conditions of such areas can provide land for shelter and agriculture for human beings. Though, there are controversies on plantation of this exotic plant, having its origin in Australia. This may be due to their unplanned, random growth or mismanagement. There should not be any doubt that this plant is a useful remedy on long term basis.

The report presents a review of the literature on the pioneering works of this area and highlights lessons learned in India, elsewhere and new trends and practices. It gives detail description of the origin, classification, hydrological and environmental aspects of its plantation. It also describes the status of waterlogging and soil salinity in various irrigation canal commands. Eucalyptus plantation as a bio-drainage means is described in particular towards solution of the widespread problems of waterlogging and salinity. A large number of eucalyptus species along with their tolerance to different classes of salinity have also been described. The study reveals potential application of Eucalyptus in this area.