Quality Assessment of Biogas Plant End Products by Plant Bioassays

Biogas technology offers a sustainable process for production of renewable energy, management of biodegradable waste, and production of nutrient-rich digestate products for fertilizing and soil improvement purposes. In order to promote the utilization of such digestate products effectively, we need more information on their quality, safety, and applicability in crop production. We have used plant bioassays to evaluate the quality and potential phytotoxicity of various digestate products obtained from three full-scale biogas plants processing organic waste and by-products from agriculture, industry and municipalities in Finland. Germination, growth and health of three test plants, including barley, Chinese cabbage, and cress, were monitored in the presence of digestate products in concentrations used in field conditions. The results suggest that both solid and liquid end products from biogas plants can be utilized as fertilizers or soil improvers for production of cereal crops such as barley.