Nutrient management in closed-loop soilless crop systems using ion selective electrodes and DSS NUTRISENSE
Dealing with the unknown mineral composition of the recycled drainage solution (DS) is a major challenge in closed-loop soilless crop systems (CLS). Currently, this issue is tackled through periodic laboratory analysis of DS followed by readjustment of the nutrient solution (NS). An attractive alternative approach involves using ion selective electrodes (ISEs) for direct measurement of macronutrient levels in the DS. However, to properly utilise the measurements obtained from the ISEs, suitable models based on mass balance and applied through an online operating decision support system (DSS) are needed.
NUTRISENSE is a DSS operating online, which was designed specifically for managing nutrition in soilless crop systems.
The main function of NUTRISENSE is the readjustment of the supplied nutrient solution (NS) based on the composition of the DS. If an ISE system is used, NUTRISENSE can recalculate daily the composition of the supplied NS based on the data obtained from ISEs to improve the accuracy of nutrient management.
Furthermore, NUTRISENSE automatically transmits the corresponding fertiliser injection rates to a fertigation system that utilizes individual fertiliser stock solutions to implement in real time the new NS composition.
To evaluate the nutrient management efficiency of NUTRISENSE when connected online with ISE, an experiment was conducted with cucumber plants grown in two CLS. The LAQUAtwin sensors (Horiba, Kyoto, Japan) were employed to measure the NO3-, K+, Ca2+, and Na+ concentrations.
In the control CLS, a standard NS composition was supplied, with EC and pH maintained close to the target levels.
In the second CLS (ISE treatment), EC, pH, NO3-, K+, Ca2+, and Na+ levels were daily measured using ISEs, while Mg2+ levels were calculated from EC values and the other cation concentrations based on the anion to cation balance principle.
The data obtained from these measurements were subsequently introduced into NUTRISENSE to calculate the readjusted NS compositions and injection rates for each fertiliser.
The LAQUAtwin ISEs proved to be highly accurate and the EC, pH, NO3-, K+, Ca2+ and Mg2+ values measured in the DS were maintained close to the corresponding target values.
The results showed that the algorithm deployed by NUTRISENSE to daily readjust the composition of the supplied NS using data from ISE measurements, is efficient and scalable for commercial application.
Giannothanasis, E., Christou, V., Ntatsi, G., Thompson, R. and Savvas, D. (2025). Nutrient management in closed-loop soilless crop systems using ion selective electrodes and DSS NUTRISENSE. Acta Hortic. 1416, 437-444
DOI: 10.17660/ActaHortic.2025.1416.57
https://doi.org/10.17660/ActaHortic.2025.1416.57
DOI: 10.17660/ActaHortic.2025.1416.57
https://doi.org/10.17660/ActaHortic.2025.1416.57
cucumber, fertigation, hydroponics, nutrient recirculation, nutrient management
English
1416_57
437-444