Co-ensiling and field wilting investigated as preparation methods for the ensiling of a wet harvested catch crop for biomethane production

Abstract

Early harvested cover crops usually present a high moisture content that makes them difficult to store by ensiling because of effluent production and undesirable butyric fermentation. In order to increase the solid content of ryegrass, field wilting (29.0 %TS) and co-ensiling with wheat straw (27.4% TS) were performed and compared with a direct storage of the crop (18.4% TS). The storage experiments were conducted at lab scale and monitored during 180 days to evaluate the fermentation pathways and changes in microbial community structure and methane potential. The addition of straw did not change the fermentation pathway during the ryegrass silage, while field wilting slowed down and decreased the occurrence of secondary fermentations. Despite the presence of secondary fermentations and VS losses up to 11%, the methane potential was efficiently preserved in all conditions. Wheat straw addition should be considered as an alternative to field wilting when unfavorable weather conditions are met.