Biodrainage potential of Eucalyptus tereticornis for reclamation of shallow water table areas in north-west India

Abstract

Ground water table (g.w.t.) levels were measured twice a month for 2 years in 50 observation wells installed inside and outside the two 18-year-old and 350 m apart plantations of Eucalyptus tereticornis (Mysure gum) at Dhob-Bhali research plot located in Rohtak district of Haryana state (north-west India). Throughout the study, the g.w.t. underneath the plantations remained lower than the g.w.t. in the adjacent fields. The average g.w.t. in the plantations was 4.95 m and the average g.w.t. in the control located in adjacent fields was 4.04 m. Interestingly, the spatial extent of lowering of g.w.t. in the adjacent fields was up to a distance of more than 730 m from the edge of a plantation. Drawdown in the g.w.t. developed due to the effect of a plantation was similar to the cone of depression of a pumping well and the drawdown in the g.w.t. developed due to the joint effect of both the plantations was similar to the combined cone of depression of two pumping wells. There was no correlation between soil salinity and the g.w.t. The fluctuations in g.w.t. caused fluctuations in g.w.t. salinity in the plantation as well as in the adjacent fields, but there was no net increase in g.w.t. salinity underneath the plantation. Sinker roots of Eucalyptus tree reached the zone of capillary fringe up to a depth of 4.40 m, indicating that the Eucalyptus trees were absorbing capillary water of the g.w.t. Thus, in shallow g.w.t. areas of semi-arid regions with alluvial sandy loam soils, the plantations of E. tereticornis act as bio-pumps and therefore, we recommend closely spaced parallel strip plantations of this species for the reclamation of waterlogged areas.