| For the quality of fodder preservation by ensiling, the oxygen level in the fermentation atmosphere is of great importance and determines the type of fermentation and the stability of the preserved feed. Corresponding investigations were generally based on destructive sampling or simulation.
In the interlinked predecessor projects DaFNE 101073 “Silage sensor RG” and DaFNE 101082 “Silage sensor”, HBLFA Raumberg-Gumpenstein and JOANNEUM RESEARCH demonstrated for the first time the use of optochemical sensor technology for minimally invasive long-term monitoring of oxygen inside a bale of grass silage, with great gains in knowledge. At that time, the method showed excellent applicability for various questions in fermentation research. However, the use of a complete optrode system (sensor+optoelectronics) for each individual measuring point was disadvantageous in terms of cost efficiency.
In order to make the technology accessible for broad research questions, this project DaFNE 101357 “SilageSens Multiplex” now pursued the approach of sequentially reading out several of the low-cost actual sensors with only one of the expensive optoelectronic units. This requires an automated switching of the optical path between the up to 16 sensors and the optoelectronics by means of integrating a fibre switch. Extensive optimisation of the optics, the sensor front ends and the user-friendliness of the software interface completed the work. For low-threshold use under real (outdoor) conditions, the entire hardware was housed in a mobile, custom-made 19-inch flight case.
As a consequence of the predecessor projects, the parallel use of sensors with different measuring ranges was realised. While trace sensors accurately reflect the level of residual oxygen in the silage, sensors with a wide measuring range record the temporal dynamics at the beginning and end of the fermentation process.
After installation, the measuring system was handed over to the HBLFA Raumberg-Gumpenstein for implementation of the sister project DaFNE 101314 “Silage Sensor2”. The results, which also show the functionality of the system, are presented in the corresponding report. From a metrological point of view, the unexpectedly pronounced ageing behaviour of the sensors, especially in maize silage, was particularly remarkable, and corresponding lessons for further use and, if necessary, technical optimisation were derived. |