Agronomic Responses and Solute Leaching Under Fertigation With Synthetic Wastewater in Two Nutrient-poor Sandy Soils

In this study, the agronomic response of radish and the leaching behavior of nutrients, salts and trace elements were investigated under fertigation with synthetic waters reproducing treated domestic wastewater, industrial effluent and landfill leachate. The water compositions were derived from a systematic review of 75 wastewater-fertigation studies and were evaluated in two nutrient-poor sandy soils through batch tests and a 40-day laboratory pot experiment. Mixed-effects models identified significant Soil & times; Water & times; Time interactions for 13 of the 14 drainage-water variables. Nitrate, sodium, chloride and potassium showed high mobility, whereas trace-element concentrations in drainage water remained low. For biomass, Soil and Water had significant main effects on all variables, whereas no Soil & times; Water interaction was detected. The nutrient-containing waters increased radish biomass relative to the deionized-water control, with the highest total dry biomass recorded under industrial-effluent fertigation in the Siliceous Riparian Sandy Entisol. In contrast, separate analyses of leaf elemental concentrations detected significant Soil & times; Water interactions for cadmium, copper, magnesium, manganese, lead and zinc. Foliar sodium reached 25.7 g kg(-)& sup1; dry matter under landfill-leachate fertigation in the Calcareous Sandy Calcisol, indicating a potential crop-quality concern. Although the synthetic waters enhanced short-term biomass production, they also promoted substantial leaching of nutrients and salts. Therefore, their agronomic use in sandy soil requires careful control of water composition, application rate and drainage, together with validation using real wastewater in longer-term and field-scale experiments.