Water productivity in cultivating the cowpea under different production systems

Abstract

The increase in irrigated areas and the water crisis in numerous regions have encouraged the use of irrigation systems and management that afford greater efficiency in the use of water. Wastewater is one option for maximising this efficiency. The aim of this study was to evaluate the indicators of water productivity in the cultivation of irrigated cowpea under different production systems. The study was carried out in the experimental area of the Sewage Treatment Station (ETE) located in Tianguá, Ceará. The experiment consisted of six production systems (treatments) in subdivided plots distributed in a completely randomised design (CRD) with fifteen replications in a (2 x 3) factorial scheme, i.e. two sources of water and energy: drinking water + electricity from the electrical grid (conventional system) and wastewater + solar photovoltaic energy (alternative system), and the different sources of fertiliser (mineral and organic), in addition to the control treatments. The water productivity indicator that expresses the relationship between the yield of the crop and the volume of water applied was determined, and the index in economic terms between crop yield and the volume of water applied. The system using wastewater and organic fertiliser showed better water productivity, 0.422 kg m-3, while the system that used drinking water with no fertiliser showed less efficiency, 0.188 kg m-3. Water use efficiency in the systems that used wastewater was higher in relation to the systems that used drinking water. Irrigation with treated domestic effluent increases water productivity and water use efficiency, in addition to being a strategy for agricultural exploitation under conditions of water scarcity