Growth and mineral accumulation in Eucalyptus camaldulensis seedlings irrigated with mixed industrial effluents

Effects of mixed industrial effluents on growth, dry matter accumulation and mineral nutrient in Eucalyptus camaldulensis seedlings were studied. The objective was to evaluate the adaptability of E. camaldulensis to effluent, tolerance to excess/deficiency of mineral elements and ultimately to determine suitable combinations of industrial/municipal effluent for their use in biomass production in dry areas. Different irrigation treatments were: T1: good water; T2: municipal effluent; T3: textile effluent; T4: steel effluent; T5: textile effluent+municipal effluent in 1:1 ratio; T6: steel effluent+municipal effluent in 1:2 ratio; T7: steel+textile+municipal effluent in 1:2:2 ratio; and T8: steel+textile effluent in 1:2 ratio. High concentrations of metal ions and low concentrations of Ca, Mg, K, Na, N and P in soil and seedlings of T4 resulted in mortality of the seedlings within a few days. Addition of the textile/municipal effluent increased the survival time of the seedlings for two to three months in T6, T7 and T8 treatments. Among the remaining treatments, the seedlings of T2 attained 131 cm height, 1.97 cm collar diameter, 19 total branches and produced 158 g seedling−1 of dry biomass at the age of 10 months. The seedling of T3 produced the least growth and biomass. Growth equivalent to that of the seedlings of T1 treatment was achieved when municipal effluent was mixed with textile effluent (T5). There was a decrease in soil pH, EC, SOC, NH4–N, NO3–N, PO4–P and basic cations and increase in the concentration of Cu, Fe, Mn and Zn with T4 treatment. The reverse trend was observed in T3 where a high concentration of Na might have reduced Mg and micronutrient concentration in seedlings potentially affecting root and leaf growth. Mixing of effluents may be useful in tree irrigation to increase biomass productivity, which is evidenced by improved growth in T5 and survival in T6, T7 and T8 treatments. Further, reduction of toxic concentration of metal ions in effluents may be helpful for a long-term field application.