Phytoremediation concept: biomass production and growth of Populus deltoides under compost leachate irrigation

Compost leachate is produced by conversion of municipal waste to compost. It contains significant amounts of organic materials, nutrients, soluble salts and small amounts of some heavy metals. Adding compost leachate to the soil can pollute it, and also improve soil fertility. In this study, we investigated absorption and growth performance of Populus deltoides under irrigation with leachate of the Compost Plant of Rasht. At the beginning of the growing season, in mid-March 2013, cuttings were processed from young, one-year-old seedlings of Populus trees in the greenhouse of the Safrabaste Poplar Research Station. Cuttings were planted in pots filled with loamy-sandy soil in the vicinity of the area with 40cm depth. Compost leachate was taken from a collection reservoir where leachate from the open composting of organic municipal wastes and various gardening and plant wastes had been collected. Five treatments were applied to plants: (C) tap water (control), (P) pure leachate, (3:1) three units (by volume) of leachate mixed with one unit of tap water, (1:1) and (1:3). The growth of tree diameter and height was measured bi-monthly. Aboveground (stem, branches and leaves) and root biomass was inventoried at the end of the growing season. Concentration of elements was determined every three months. Overall, growth parameters in 1:1 and 1:3 treatments were similar together and there were no significant differences between them (P < 0.05). Pure treatment had minimum growth because of a high concentration of solvable salts in leachate such as sulphur that causes salinity and high EC in soil. Treatment1:3 exhibited the greatest overall aboveground and root dry mass. Total aboveground dry mass of leachate treatments and water was 202.25 and 47.58 g, respectively.