Studienarbeit, 2015, auf Französisch
Ophélie Rollin

Summary

Wildflowers mixtures are recently grown as flowering strips on arable fields to increase the diversity in the agricultural landscape, especially in areas dominated by maize grown for biogas production.  According to the suppliers of the mixtures, wildflower mixtures can be harvested and ensiled simultaneously with the maize and, thus, be used for biomethanization. Nevertheless, the addition of wildflower biomass changes the quality of silage and, therefore, impacts the efficiency of anaerobic digestion in biogas plants.

The purpose of this project was to analyze the quality of maize silage that contained 1/3 or 2/3 wildflowers biomass or only wildflowers biomass, with regard to dry matter content, crude ash and patterns of organic acids and alcohols. The quality was compared to that of silage made solely from good and moderately quality maize, as well as to standards for high-grade forage silage. The trials were conducted at laboratory scale with three replicates for each of the wildflower mixtures and ten replicates for each of the maize silage treatments, and analyzed after ten months ensiling.

Dry matter contents, crude ash and pH-values were higher in silage made of wildflowers mixtures than in pure maize silage. However, the concentrations of ethanol, propanol, acetic acid, lactic acid and ammoniacal nitrogen were lower. Surprisingly, silage made of wildflower mixtures met the standards for high-grade forage silage, and not silage made from the pure maize. In maize silage, the concentrations of ethanol and ammoniacal nitrogen were too high, indicating the undesirable activity of yeasts and heterofermentative lactic acid bacteria or clostridia, respectively. Possibly, the higher dry matter content in the wildflower mixtures compensated for the negative effects. Of course, the results of this laboratory trial need to be confirmed by experiments designed to test the digestability of silage made from different mixtures.