Field comparison and crop production modeling of sweet corn and silage maize (Zea mays L.) with treated urban wastewater and freshwater

Abstract

In Australia, interest in wastewater reuse has grown. While wastewater can potentially offer a nutrient advantage over conventional irrigation, crop yield increases may be offset by effects of high salinity. Effects of wastewater irrigation on crop production and soil health were investigated in two ways: a field experiment addressing short-term effects and modeling longer-term impacts. The field experiment was established at the Shepparton Wastewater Treatment Plant in Shepparton, Victoria, to compare effects of wastewater irrigation to conventional irrigation. Silage maize and sweet corn (Zea mays L.) were grown over the summer of 2012–2013 under the following flood irrigation treatments: wastewater and freshwater with and without fertilizer. Both harvests produced yields and qualities comparable to commercial farm standards, and no significant differences were found between water types. Maize production with long-term wastewater irrigation at various salinities was modeled, and no significant yield losses were observed after 50 years of simulated irrigation. Topsoil electroconductivity doubled after the field trial and simulation results predicted significant soil salt accumulation by factor of 2. Mean wastewater sodium absorption ratio of 4.52 and electroconductivity of 1.52 dS/m indicate potential for sodicity-related soil problems for long-term irrigation. Management of soil health may be necessary.