Is it possible to increase the mineral content of culinary herbs by supplying the drainage of hydroponically-grown cucumber plants?

In vegetable production, large amounts of water and fertilizers are needed, especially for hydroponic systems.
To avoid losses of resources, the nutrient-rich drainage might be used for cultivation of other crops such as soil-grown herbs.
It was thus tested whether the drainage solution from cucumber cultivation could be used to increase the content of minerals in the leaves of the culinary herbs rocket and basil in a hydroponic system.
The cucumber plants were supplied with water and fertilizer by drip irrigation in a greenhouse.
The herbs received either the original nutrient solution of the cucumbers (control) or their drainage.
The above-ground biomass of the herbs was harvested when they reached marketable size.
The content of mineral elements was assessed from dried leaves.
Basil plants supplied with the drainage of the cucumbers had lower dry mass upon harvest, and lower nitrogen contents of the leaves as compared to the controls.
In contrast, rocket plants showed little significant effects of the fertigation with cucumber drainage on above-ground biomass and N contents in the leaves.
The drainage of the cucumbers had more nitrate and other mineral elements, with exception of K which was less than in the control.
Consequently, the plants that received the drainage had reduced K contents in the leaves.
The use of drainage from hydroponically-grown cucumbers may thus be used for the cultivation of rocket and basil, but it is not possible to increase the concentrations of all mineral elements in the edible parts of these herbs.

IV International Symposium on Horticulture in Europe – SHE2021

L. Schmidt, F. Langner, O. Löhnertz

basil, rocket, fertigation, re-used nutrient solution

https://doi.org/10.17660/ActaHortic.2021.1327.98