Simulation of hydroponic production using rainwater and brackish water

Food production is the most water-demanding activity in the world. Thus, the need for using cultivation techniques that mitigate water scarcity is increasing. Hydroponics is a production system usually used under protected environments, providing significant water savings and high crop yields. Considering the importance of developing alternatives for agricultural production, the objective of this work was to develop a model that allows the use of rainwater or rainwater combined with brackish water for hydroponic crops. Rainfall data were used to determine the daily water balance in the model. A spreadsheet was developed to facilitate the use of the model, enabling the determination of the rainwater tank volume required to maintain the electrical conductivity level tolerated by hydroponic crops. Three case studies on coriander and lettuce production, conducted in Juazeiro, Senhor do Bonfim, and Cruz das Almas, BA, Brazil, were presented. The model was evaluated based on the main input variables. The model for an annual tank volume was more sensitive to variations in evaporation. The model for a multiannual tank volume was more sensitive to the number of annual crop cycles. Both water volumes presented less sensitivity to variations in the catchment area.