We tested the hypothesis that reduced leaching and prolonged residence time in the soil profile will enhance the uptake of nutrients, the biodegradation of OM and the die-off of enteric bacteria introduced by effluent irrigation. A lysimeter simulation study was conducted where Eucalyptus trees were planted in tree soils and either fertigated or irrigated with oxidation ponds effluent (OPE). Irrigation was three times daily, every day. The trees were very resistant to increasing salinization of the soil solution, caused by low leaching fraction. Data from the 2nd year of the experiment is presented. Applied nitrogen was nearly completely intercepted in the soil-tree system, which was yet less efficient with respect to phosphorus (except in the more calcareous clay soil). The simulation study showed that inasmuch as the trees withstood elevated salinity levels and the soil-plant effectively intercepted organic and inorganic pollutants, the long term quality of the soil was endangered.