Irrigation water quality from wastewater reuse or groundwater sources: bridging the water-nutrient-food nexus

A field study is done to analyze the effects of water reuse for irrigation with a focus on seed germination, crop morphology, crop yield, nutritional values of edible parts, fertilizer reduction, and benefit-cost ratio. For the study, three different crops, Lablab bean, tomato, and chilli, are considered and every crop type is irrigated with groundwater (GW), diluted treated wastewater (DTWW), and treated wastewater (TWW). The study reveals that the DTWW is optimal for seed germination. Crops irrigated with the TWW have the highest morphological characteristics. Crop yield is highest for the TWW-irrigated Lablab bean and DTWW-irrigated tomato. Chilli remains unproductive until the end due to thermal stress. Nutritional values of the edible parts of the DTWW- and TWW-irrigated crops are lower than the GW-irrigated crops. Crops irrigated with the DTWW and TWW are applied with the reduced quantities of N, P and K fertilizers. Indeed, even when the dosages are low those crops are able to produce higher yields than the GW-irrigated crops which are applied with full fertilization. As the crop yield is high and fertilizer cost is less, the benefit-cost ratio is higher for water reuse irrigation than the GW irrigation.