A novel smart fertigation system for irrigation with treated wastewater: Effects on nutrient recovery, crop and soil

Both southern and northern regions of Italy are experiencing reduced precipitation and increased heat waves due to climate change, negatively affecting agricultural sector. Urban wastewater could be a solution to this problem, providing a constant source for irrigation and reducing synthetic fertilizer use. This research presents a two-year field study on using tertiary treated wastewater for processing tomato crop irrigation through an innovative smart fertigation system, designed to supply the exact doses of NPK nutrients considering those already delivered to the plants via the irrigation water. With the aim of studying the effects of irrigation with treated wastewater, three water sources were compared: fresh water added with chemical fertilizer, tertiary treated wastewater added with chemical fertilizer and tertiary treated wastewater without addition of fertilizer. The proposed system was efficient and consistent with the design, it saved considerable amounts of fertilizers, handling nutrient fluctuations in wastewater. Of the three irrigation water types that have been tested, only the one that used tertiary treated wastewater alone without additional fertilizers was not capable of meeting tomato nutritional needs, despite the fact that significant macronutrient savings were achieved. No negative effects on soil or plant physiological performances were observed. Plants irrigated with wastewater showed similar growth and productivity to those irrigated with fresh water and no significant differences in fruit quality were found, highlighting the benefits of wastewater reuse for crop irrigation.