Drip Irrigation with Sewage Effluent Increased Salt Accumulation in Soil, Depressed Sap Flow, and Increased Yield of Tomato

Abstract

AbstractSewage application is a cost‐effective method for meeting the challenge of irrigation in water‐short regions. However, there is concern about the accumulation of salt from sewage effluent in soil. Experiments were conducted for 3 years in a greenhouse to investigate the effects of water quality on salt accumulation in soil and on sap flow for drip‐irrigated tomato. The types of irrigation water used in the experiments included secondary sewage effluent, groundwater, and blended water that was obtained by mixing the secondary sewage effluent and the groundwater in equal volumes. The results demonstrated that soil bulk electrical conductivity (ECb) increased with irrigation rates, and sewage application produced a more rapid increase than did blended water and groundwater treatments. Irrigation throughout the growing season could produce a 21–44% increase in salt content from its initial values to values at harvest, and salt accumulation occurred mainly at the 30–45 cm depth of soil. Sewage irrigation was likely to decrease sap flow but increased tomato yield and improved fruit quality parameters excluding ascorbic acid compared with groundwater irrigation. These results suggest that secondary sewage application using drip irrigation increases salt accumulation in the root zone, and depresses crop transpiration to some extent, but does not have a negative influence on tomato yield and fruit quality. Copyright © 2017 John Wiley & Sons, Ltd.