The chemical composition and potential nutritive value for ruminants of fresh energy crops, Jerusalem artichoke cv. Topianca (Helianthus tuberosus L.) and cv. No. 1168 (Helianthus tuberosus × annuus), lucerne (Medicago sativa L.) and Garden orach (Atriplex hortensis L.), and their residues after they were subjected to anaerobic fermentation were studied.

The above-ground growth (stems and foliage) of Jerusalem artichoke (Helianthus tuberosus L.) was studied in field experiments in Sweden during 1981 to 1983, in order to investigate the possibility of producing biogas from biomass. Dry matter yields of three varieties were determined at four different harvesting times. The yields varied between 7 and 16 tons of dry matter per hectare. Anaerobic digestion experiments showed that fresh and ensiled above-ground parts of the plant could produce 480–680 litres biogas per kg organic material. The chemical composition of the plant material was determined before and after digestion.