During the last few months four students of the University of applied sciences 'InHolland' in Delft have been investigating the oxygen contents in deep flow cultivation systems to achieve their Bachelor. Their main goal was to determine an uniform measuring method and to describe it into a protocol and to compare it with measurements. Deep flow cultivation (=DFT) takes place in a pond of 10-30 cm deep which is covered by a floating panel. The system is being investigated at chrysanthemums, lysianthus and lettuce in greenhouses and leek and lettuce outside. Using this new system new problems arose which were earlier unknown in these crops. Often oxygen deficiency is thought to be the factor. The students enquiry delivered many measuring methods en many symptoms of disturbed growth. However, sometimes symptoms corresponded with low oxygen concentrations, but often there was no match.
In their project the students interviewed growers and researchers and measured in various systems. The result is a measuring protocol with which data are better comparable. Important issues are flowing patterns of the water, time of the day and weather conditions and a systematic identical measurement between the roots in such a way that data are comparable with a next measurement. Last but not least is the importance of using an oxygen meter which is clean and calibrated.