TY - JOUR

T1 - Anaerobic co-digestion of perennials

T2 - Methane potential and digestate nitrogen fertilizer value

AU - Müller-Stöver, Dorette Sophie

AU - Sun, Guotao

AU - Kroff, Pablo

AU - Thomsen, Sune Tjalfe

AU - Hauggaard-Nielsen, Henrik

PY - 2016/12/1

Y1 - 2016/12/1

N2 - 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 amounts together with animal manure. The nitrogen (N) mineralization dynamics in soil and the N-fertilizer value of the derived digestates were subsequently tested in both a soil incubation study and a pot experiment with spring barley. Digestion of all tested perennials together with a manure-based inoculum increased the cumulative methane yield four to five times compared to digestion of the inoculum alone, with the highest increases observed with pure grass. However, the methane 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. Considering the high dry matter and methane yield ha−1, the possibility to substitute mineral N fertilizer inputs by leguminous biological N2 fixation capacity, and the digestate fertilizer value, the integration of grass–legume mixtures or sole legumes into anaerobic digestion systems as co-substrate for manure seems to be promising. This could furthermore contribute to the diversification of cropping systems for bioenergy production.

AB - 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 amounts together with animal manure. The nitrogen (N) mineralization dynamics in soil and the N-fertilizer value of the derived digestates were subsequently tested in both a soil incubation study and a pot experiment with spring barley. Digestion of all tested perennials together with a manure-based inoculum increased the cumulative methane yield four to five times compared to digestion of the inoculum alone, with the highest increases observed with pure grass. However, the methane 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. Considering the high dry matter and methane yield ha−1, the possibility to substitute mineral N fertilizer inputs by leguminous biological N2 fixation capacity, and the digestate fertilizer value, the integration of grass–legume mixtures or sole legumes into anaerobic digestion systems as co-substrate for manure seems to be promising. This could furthermore contribute to the diversification of cropping systems for bioenergy production.

KW - alfalfa

KW - biogas

KW - grass

KW - perennials

KW - red clover

U2 - 10.1002/jpln.201500599

DO - 10.1002/jpln.201500599

M3 - Journal article

AN - SCOPUS:84992116336

VL - 179

SP - 696

EP - 704

JO - Journal of Plant Nutrition and Soil Science

JF - Journal of Plant Nutrition and Soil Science

SN - 1436-8730

IS - 6

ER -