Bio-drainage for salinity control: Myth or reality for Indian monsoonal climate

Bio-drainage for salinity control: Myth or reality for Indian monsoonal climate

wca2014-2448 P S Minhas 1,* 1Director, National Insitute of Abiotic Stress Management, Baramati, Pune, Pune, India

The prime requirements for rehabilitating salinity afflicted land are that of reverting the flux of water for leaching salts beyond active root zone. Though engineering approaches like surface and subsurface drainage have been standardized for rehabilitating the saline waterlogged soils, their adoption on large scale is hindered by high capital investment, associated operational and maintenance problems in addition to suitable alternatives for drainage water disposal. As an alternative, use of plantations (bio-drainage) is being advocated as ‘eco-friendly’ option without any long term experimentation and verification.  The main force behind such a notion is high water use and deeper rooting systems of tree. In fact plantations, especially Eucalyptus have been shown to draw down water-table, of course their spatial extent being governed by tree transpiration rates and hydraulic characters of soils. We determined the sap flow values for a whole life cycle (10 years) of irrigated Eucalyptus plantations at various densities. The annual values increased from 53-140 cm (increment of about 14cm/y) between 2 to 6 years and stabilized thereafter indicating little advantages of trees over crops (rice/maize/cotton-wheat) will occur only after about 5 years of plantations. The values improved considerably with density plantation (96-160 cm/y) but for these to be effective, land requirements would be very high. The other issue related to plantations is salt accumulation, once the deeper rooted trees skim out the water.  All these factors indicate towards the myths being created for bio-drainage without presenting the real data from long term experimentation and validation. The alternatives proposed to overcome salt problems are ‘walking plantations’, boundary plantations and even integrating sub-surface drainage and tree plantations. The utilization of recent tools in GIS and RS for prognosis of hot spot areas to be covered under plantations, further information on high density plantations of tolerance tree species, hydraulic parameters of soils and models to predict salinity with plantations should help in afforestation designs and highlight management options and priorities

Vigyan Bhavan & Kempinski Ambience

10 - 14 February 2014 Delhi, India