# HydroLab: A Module for the Investigation of Fertigation Strategies in Hydroponics
## 4 Case Study
### Experimental Setup  
HydroLab was utilized as the test bench for the experiment as it allows the cultivation of two independent crop samples. To ensure a fair and controlled comparison, all variables were kept consistent between the two crop samples, except for the triggering event that initiated the fertigation process. The adjustable suspension was set to an _inclination_ of 5\({}^{\circ}\) for both samples, and _lettuce seedlings_ grown under the same conditions were used.  
_Coconut coir_ was adopted as the substrate since [27]: (i) it exhibits excellent water retention capacity, allowing for proper moisture levels within the root zone, which is essential for the growth and development of lettuce plants; (ii) it possesses adequate drainage properties, ensuring the efficient removal of excess water and preventing waterlogging, which can be detrimental to plant health; (iii) the physical structure of its fibers provides a favorable environment for root penetration and aeration, facilitating nutrient uptake and promoting robust plant growth. Coco Elite ([[https://saenzfety.com/wp-content/uploads/products/176/pdf/ft_coco_elite.pdf](https://saenzfety.com/wp-content/uploads/products/176/pdf/ft_coco_elite.pdf)]([https://saenzfety.com/wp-content/uploads/products/176/pdf/ft_coco_elite.pdf](https://saenzfety.com/wp-content/uploads/products/176/pdf/ft_coco_elite.pdf)) (accessed on 18 July 2023)) was used due to its fine particle size, excellent moisture retention, and good aeration properties.  
The module was installed within the _Uniandes Controlled Environment Agriculture Laboratory_ ([[https://revisatoconato.uniandes.edu.co/contaco-21-transformacion-digital/u](https://revisatoconato.uniandes.edu.co/contaco-21-transformacion-digital/u)]([https://revisatoconato.uniandes.edu.co/contaco-21-transformacion-digital/u](https://revisatoconato.uniandes.edu.co/contaco-21-transformacion-digital/u)) n-banco-de-pruebas-para-optimizer-cultivos-hidroponicos/ (accessed on 18 July 2023)) (Figure 5), which is an 18 m\({}^{2}\) glass greenhouse located at 4\({}^{\circ}\) N, 74\({}^{\circ}\) W. This setting ensured that both crop samples experienced the same microclimate conditions, reducing environmental variability during the experiment.  
The utilized _nutrient solution_ is illustrated in Table 3. This recipe was provided by [PERSON] ([[https://saenzfety.com/](https://saenzfety.com/)]([https://saenzfety.com/](https://saenzfety.com/)) (accessed on 18 July 2023)). During the preparation of the solution, meticulous attention was given to pH and EC measurements. As suggested in [28], the pH of the solution was carefully adjusted and maintained within the range of 5.8-6.0, while the EC was between 2.2-2.4 dS/m.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Component** & **Units** & **Cost [USD]** \\ \hline Mesh Filter & 2 & 34 \\ Diaphrag pump & 2 & 80 \\ Raspberry Pi & 1 & 34 \\ Pyramometer & 1 & 950 \\ PLC & 1 & 493 \\ \hline
**Total cost** & & **2563** \\ \hline \hline \end{tabular}
\end{table}
Table 2: _Cont._  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Nutrients** & **Quantity [g/10 L]** \\ \hline Calcium nitrate & 6.10 \\ DTPA Fe & 0.19 \\ Potassium nitrate & 4.20 \\ Magnesium sulfate & 3.60 \\ Monopotassium phosphate & 2.10 \\ Manganese sulfate & 0.19 \\ Zinc sulfate & 0.07 \\ Copper sulfate & 0.06 \\ Solubor Fe & 0.11 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Nutrient solution utilized for the experiment.