From crops to biogas-anaerobic digestion of mixed silage of cover crops and straw: The influence of manure addition and impact on microbial community structures.

Cover cropping is important for nutrient management of agricultural systems as it can retain the nitrogen and make it available for the succeeding crops. It also has a largely unexploited potential for biogas production. This study evaluates the anaerobic digestion of cover crop silage (mainly consisting of red clover), co-ensiled cover crop and straw (with various mix ratios) either alone or with addition of animal manure. The effect of feeding compositions (straw or manure addition) on the microbial community structures was also investigated. Results demonstrated that cover crop (silage) is feasible for either crop-digestion or co-digestion with addition of cattle manure, while manure addition led to higher CH4 yield, volatile solids reduction, and buffer capacity. Microbial community compositions were affected greatly by the feeding, and the digesters fed with high share of straw altered the bacterial community structure most.