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„Microbial carbonisation“ compared with composting

„Microbial carbonisation“ (mC) according to Witte was tested as a possible alternative to aerobic composting. In this process, a compost-like end product is to be produced through a low-loss process in a low-oxygen environment.

A comparative trial of the two processes was carried out in Burgenland: Both windrows were set up with on-farm and locally available material and were well homogenised: 13 (vol.-)% wood chips, 15 % sheep manure, 13 % strawless horse manure, 21 % hay, 24 % soy chaff, 21 % barley chaff. The mC windrow was compacted in a moist state with a front-end loader and given a cover of barley chaff to protect it from evaporation.

After setting up, both windrows reached temperatures of 60-70 °C, but the mC windrow did so only in the core, not in the outer area. While the compost windrow again briefly exceeded 70 °C after each turning, the un-turned mC windrow kept temperatures of 40-50 °C inside for much longer.

After about 5 months, the two materials differed significantly. The mC process was inhomogeneous, especially in the outer area. The microbial activity was still significantly higher in the mC material and it had reached a significantly lower maturity.

The main disadvantages of the mC process are the inhomogeneity of the material obtained and the fact that it is not possible to control the timing of the process through targeted turning so that the compost is ready for application at the appropriate time.