SPINACH (Spinacia oleracea L.) RESPONSE AND ACCUMULATION OF SALTS IN SOIL UNDER SURFACE AND SUBSURFACE WASTEWATER IRRIGATION

Demand for higher agricultural yield has enhanced the use of wastewater for irrigation. This study was carried out to compare surface- and subsurface irrigation on the growth, water use efficiency (WUE), nutrient uptake of spinach (Spinacia oleracea L.) and accumulation of soluble salts in the soil. Results showed that crop response was significantly affected with the wastewater irrigation. Subsurface wastewater irrigation increased plant growth than surface irrigation. Higher biomass was produced with the application of sewage and municipal wastewater. The lower biomass was noticed in the industrial wastewater. Higher application of wastewater significantly reduced WUE. An enhanced WUE was achieved with subsurface irrigation. Higher concentrations of nutrients in the plants were achieved under 100% both surface and subsurface irrigation than 50% irrigation. Surface irrigation enhanced concentrations of elements in plants. Calcium and Mg concentrations in plants were obtained as sewage water > industrial waste water > municipal wastewater > fresh water. Heavy metals concentrations in plants remained identical to other elements under both irrigation systems. Higher accumulation of salts occurred in the 2nd layer (30-60 cm) of the soil column under 100% surface irrigation. Wastewater differed for soil Ca in the order of sewerage water > industrial wastewater > municipal wastewater > fresh water. Potassium and Mg concentrations were higher in the 3th layer (60-100 cm) of soil under subsurface irrigation. Wastewater differed for K concentration in soil: sewage water > municipal wastewater > industrial wastewater > fresh water. Higher EC was seen in the middle layer of columns where greater accumulations of cations occurred. Irrigation with 100% PE increased EC more than 50% PE irrigation water.