Any variation of a parameter from optimum conditions results in the microbial activity being limited accordingly. The conversion then is not optimal and the compost produced is not of the desired steady quality. This limits the utilisation, for example as peat substitute material in horticulture. Accordingly, optimum moistening of the biomass is a very important parameter of composting. However, the determination of this quantity still poses a serious problem today. All conventional methods of humidity determination are considerably limited in this field of application. Tests with known conventional humidity sensors have proved that there methods are too inaccurate, too slow or not practicable.
The present contribution describes a measuring instrument which allows the humidity of the organic material to be determined without influencing the composting process. The method for the determination of the water concentration is based on the absorption of electromagnetic radiation by the water molecules.