Pilot-scale digesters (850 L) were used to quantify CH4 and H2S production when using forage radish
cover crops as a co-digestion feedstock in dairy manure-based digesters. During two trials, triplicate
mixed digesters were operated in batch mode with manure-only or radish + manure (27% and 13% radish
by wet weight in Trial 1 and 2, respectively). Co-digestion increased CH4 production by 11% and 39% in
Trial 1 and 2, respectively. As H2S production rapidly declined in the radish + manure digesters, CH4 production
increased reaching high levels of CH4 (P67%) in the biogas. Over time, radish co-digestion lowered
the H2S concentration in the biogas (0.20%) beyond that of manure-only digestion (0.34–0.40%),
although cumulative H2S production in the radish + manure digesters was higher than manure-only.
Extrapolated to a farm-scale (200 cows) continuous mixed digester, co-digesting with radish could
generate 3150 m3 CH4/month, providing a farmer additional revenue up to $3125/month in electricity