Anaerobic co‐digestion of perennials: Methane potential and digestate nitrogen fertilizer value

Bidragets oversatte titel: Samudrådning af fleårige græsmarksafgrøder: methan potentiale og kvælstofgødningsværdig af afgasset materiale

Dorette Sophie Müller-Stöver, Guotao Sun, Pablo Kroff, Sune Tjalfe Thomsen, Henrik Hauggaard-Nielsen

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review


Co-digestion of crop biomass improves the traditional manure-based biogas yield due to an increased content of easily degradable carbon compounds. In this study, the methane potential of three perennials (grass, legumes, and grass+legume) was determined using various concentrations together with animal manure. The N mineralization dynamics in soil and the N-fertilizer value of the derived digestates was subsequently tested in both a soil incubation study and a pot experiment with spring barley as model crop.
Digestion of all tested crops together with a manure-based inoculum increased the cumulative methane yield 4 to 5 times compared to digestion of the inoculum alone, with the highest increases observed with pure grass as a substrate. However, the biomethane potential decreased along with increasing grass biomass concentration. In the plant pot experiment, all tested digestates increased barley shoot biomass by 40-170%, to an extent statistically comparable to mineral N fertilizer. However, the application of the digestate originating from fermentation with pure grass resulted in lower plant growth and a more fluctuating soil mineral N content throughout the incubation study compared to the other digestates.
The integration of grass-legume mixtures or sole legumes into anaerobic digestion systems as co-substrate for manure seems to be promising, especially when considering their high dry matter and methane yield ha-1 and the possibility to substitute mineral N fertilizer inputs utilizing leguminous biological N2 fixation capacity. This could contribute to the diversification of cropping systems for bioenergy production.
TidsskriftJournal of Plant Nutrition and Soil Science
Udgave nummer6
Sider (fra-til)696-704
Antal sider8
StatusUdgivet - 2016


  • lucerne
  • biogas
  • græs
  • fleårige afgrøder
  • rødkløver

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