Effect of wastewater and compost on leaching nutrients of soil column under basil cultivation

This study was conducted to determine the effects of wastewater and compost on soil leaching nutrients, under basil cultivation. To this regard, a factorial test based on completely randomized design with two factors and three replications was applied. The experiment was carried out in the greenhouse of Bu-Ali Sina University, Hamedan, Iran. The first factor was water quality: fresh water (W1), raw wastewater (W2) and treated wastewater (W3) the second factor was compost level: 0 (C1), 40 (C2), 80 (C3) and 120 t ha−1 (C4). Therefore, 12 treatments (W1C1–W3C4) were investigated. 36 cubic (30 cm × 30 cm × 126 cm) metal lysimeters were designed. Lysimeters contained a three-layer soil (from top to bottom) including: 30 (clay), 40 (clay loam) and 40 cm (sandy loam), respectively. After lysimeters preparing, basil was planted in the top soil. Eleven watering with an average interval of 10 days were used during planting season. Nitrate, phosphate and potassium of leaching water were analyzed after each watering. Also, the basil yield and nutrients were analyzed in three harvesting stages. The result showed wastewater and compost could increase all leached nutrients comparing to the control. In all treatments, cumulative concentrated nitrate, phosphate and potassium in soil profile ranged from 36.13 to 142.05, 0.33 to 1.05 and 57.6 to 125.34 mg/l, respectively. The minimum and maximum amounts of nitrate, phosphate and potassium in drainage water were 2.56 and 21.40, 0.01 and 0.16 and 1.04 and 16.35 mg/l, respectively. Also, using wastewater and compost increased the basil yield and nutrients. In most of treatments, nitrate concentrations were greater than the standard rate allowed for human consumption. Based on the result, potential for nitrate, phosphate and potassium leaching from wastewater and compost amended could be reduced by establishing a plant cover.