Models of oxygen profiles in growing media and their use as a cultivation tool

To be able to use oxygen control in the root environment as cultivation tool, it is necessary to obtain representative profiles of the oxygen content within substrates. It was the aim of the current project to study whether it is possible to obtain oxygen profiles within substrates using a limited amount of oxygen measurements in the root environment, which are subsequently coupled to a model. In this model, correlations between oxygen and some other growth conditions should be described. Next, it was studied whether this technology can be used to develop a measurement tool for practical use. The following results were obtained: A multi-oxygen sensor was constructed for determination of large numbers of oxygen measurements, which can be simultaneously measured at different locations in growing media (stone wool). Data has been generated, both from measurements at the laboratory and in the green house during growth of tomatoes. Besides oxygen, several other parameters were measured, which may be related to oxygen contents, such as water content, light, temperature, EC, RV. Data sets were analyzed, and a concept model was developed, that describes relationships between the oxygen and other parameters. Our results indicate that it is possible to develop an oxygen measuring strategy, which can be used to determine a representative pattern of oxygen levels in growing media. Also, it seems likely that a sensor can be constructed (i.e., the "software oxygen sensor"), which contains besides sensor hardware, also a (software) model, which describes relationships between different growth conditions.