# HydroLab: A Module for the Investigation of Fertigation Strategies in Hydroponics
## 6 Conclusions and Future Work  
Food security poses a critical challenge as the global population surpasses 7.8 billion and is steadily growing. Traditional soil-based agriculture has the capacity to produce significant quantities of food, but it often comes with negative environmental impacts. In response to this context, hydroponics has emerged as a popular solution. Hydroponics offers an environmentally friendly alternative that promotes higher crop yields and improved quality, while eliminating the reliance on soil. In hydroponics, fertigation is recognized as a pivotal activity, and its demands are subject to numerous factors, including plant species, cultivar, growth stage, utilized substrate, season, and climate conditions. Given the absence of standardized knowledge and the intricacy of the matter, test benches play a fundamental role in exploring and evaluating effective fertigation strategies. The literature presents various test benches designed for investigating fertigation strategies. However, to the best of the authors' knowledge, no test bench has been proposed that is capable of simultaneously exploring multiple types of fertigation strategies. Based on the aforementioned considerations, the objective of this research was to propose a flexible test bench capable of offering a controlled and adaptable environment for conducting experiments and evaluating the effectiveness and efficiency of various fertigation strategies. To fulfill this objective, the researchers developed HydroLab, a module that enables the simultaneous comparison of two types of fertigation strategies and can be remotely monitored and controlled through IoT functionality. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Strategy** & **Height [cm]** & **Weight [g]** & \
\begin{tabular}{c} **Nutrient Solution** \\ **Consumption [L]** \\ \end{tabular} & **Yield [g/cm\({}^{2}\)]** &
\begin{tabular}{c} **Nutrient Solution** \\ **Efficiency [g/L]** \\ \end{tabular} \\ \hline Time-based Fertigation & 23.9 \(\pm\) 0.8 & 218.0 \(\pm\) 7.4 & 10.9 & 2.2 & 20.0 \\ Radiation-based Fertigation & 27.2 \(\pm\) 0.6 & 256.2 \(\pm\) 8.0 & 9.8 & 2.6 & 26.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Logging indicators obtained in the implemented experiment. Height, weight, and nutrient solution consumption were calculated based on the average of the 8 plants in each row. To validate the effectiveness of HydroLab in investigating fertigation strategies in hydroponics, a case study was conducted that compared a time-based and a solar radiation-based fertigation strategy in lettuce cultivation. Throughout the experiment, all variables were carefully controlled and maintained consistent between two independent crop samples, except for the triggering event that initiated the fertigation process. The HydroLab module operated autonomously during the case study, and the authors were able to remotely monitor its proper functioning through the implemented HMI interface. The results of the case study demonstrated that solar radiation-based fertigation outperformed the time-based strategy in terms of effectiveness and efficiency, as indicated by higher yield and nutrient solution efficiency. While these findings are promising, further experiments are necessary before considering radiation-based fertigation as a technological recommendation. Nevertheless, the case study successfully showcases the capability of HydroLab in investigating and comparing different fertigation strategies. Notably, the proposed test bench constitutes a preliminary concept that should be further validated and improved in the future. Some future works identified are:  
* _Nutrient solution module_: In HydroLab, the crop rows receive the same nutrient solution. Therefore, it would be desirable to have a module able to automatically generate a nutrient solution with pre-set values of pH and EC for each crop row;
* _Technological recommendations_: Enhancements are needed to convert HydroLab into a tool capable of providing technological recommendations.