Determination of ammonia exposure of potted herbs in organic cultivation

ISHS Secretariat
Determination of ammonia exposure of potted herbs in organic cultivation

Christian Frerichs is a PhD student at the Osnabrück University of Applied Science, Germany, supervised by Prof. Diemo Daum as well as Prof. Gabrielle Broll from the Osnabrück University. His research focuses on strategies to reduce the risk of nitrogen losses by ammonia volatilization and nitrate leaching in vegetable production. To assess this, he has conducted a series of fertilizer and field management trials with basil (Ocimum basilicum L.) in the greenhouse, as well as field-grown spinach (Spinacia oleracea L.). In the poster presentation entitled “Determination of ammonia exposure of potted herbs in organic cultivation”, he described an easy-to-use measuring system for the detection of gaseous ammonia in greenhouse pot plant production. In organic cultivation of pot-grown herbs particularly, ammonium concentrations and substrate pH may temporarily increase, which facilitates ammonia volatilization. Basil growth can be inhibited and plant damage can occur under such substrate conditions. The objective of this project was to distinguish the effect of both ammonical nitrogen species (ammonium and ammonia) on plant performance. An open top chamber approach was developed and evaluated. The results show that when ammonia concentrations were above 0.2 ppm, the open top chamber measurements corresponded with data from passive samplers as well as calculated concentrations based on known substrate equilibrium and air temperature. In this way, Christian used the new approach to compare different substrate storage and fertilization treatments that can reduce ammonical nitrogen exposure in pot-grown basil production. However, plants were affected at concentrations below 0.2 ppm ammonia. Therefore, the sensitivity of the new approach has to be improved in the lower concentration range.

Christian Frerichs won the ISHS Prof. Jens Wünsche Young Minds Award for the best poster at the IV International Symposium on Horticulture in Europe (SHE2021), which was held virtually in Germany in March 2021.

Christian Frerichs, Osnabrück University of Applied Science, Am Krümpel 31, 49090 Osnabrück, Germany, e-mail:

The article is available in Chronica Horticulturae

ammonia exposure
Young Minds Award Winners