Use of tree seedlings for the phytoremediation of a municipal effluent used in dry areas of north-western India: Plant growth and nutrient uptake

Impacts of municipal effluent (ME) irrigation on soil physicochemical properties and its remediation by tree species were assessed with a view to utilize this resource in growing woodlot, controlling land degradation and improving environmental quality in suburban areas. Acacia nilotica L. (babool), Dalbergia sissoo L. (sissoo) and Eucalyptus camaldulensis seedlings planted in July 1998 were irrigated with ME at ½ PET (T2), 1 PET (T3), 2 PET (T4), and with canal water at 1 PET (T5). The control was soil without seedlings irrigated with ME at 1 PET (T1). Application of ME increased minerals concentration from T2 to T4 in both soil and seedling in June 1999 and 2000. The increase in soil pH, EC, SOC was by <2.00-fold and availability of potassium (K), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) by >2-fold, NH4–N by 10.44-fold and PO4–P by 6.57-fold in T4 than those in T5 treatment in 2000. Available NH4–N, PO4–P, Mg and K were higher in 0–15 cm soil layer but continued irrigation and low soil carbon influenced leaching of NO3–N, Na, Cu, Fe, Mn and Zn resulting their higher concentrations in 60–90 cm soil layer (P < 0.01). Lower soil nutrients in T3 than in T1 suggested soil amelioration by the planted seedlings and because of lowest concentration of most of the nutrients E. camaldlensis showed highest soil amelioration capacity. But nutrient utilization efficiency was highest in A. nilotica for K, Ca, Mg, Na, Fe, Cu and Zn, D. sissoo for N and P, and E. camaldulensis for Mn. Thus, planting tree seedlings, particularly E. camaldulensis, under ecological amelioration could in this way help in controlling land degradation and enhancing biomass and aesthetic benefits, although long-term application of effluent would lead to mineral/salt accumulation in soil and plants.