Evaluating alternatives for co-product use in European agriculture: Does regional context matter?

Integrated agricultural systems which connect crops, livestock, industry, and consumers through recycling of co-products potentially reduce losses to the environment and utilise inputs more efficiently. This study assesses how co-product use in agriculture affects food production and its environmental performance in multiple European regions, and evaluates how regional context affects the optimum use of available co-products. An exploratory nitrogen flow model, including quantification of greenhouse gas (GHG) emissions, effective organic matter (EOM) inputs, and energy use, was applied to assess co-product use options across four European regions: Ariège (Southern France, A-FR), Drenthe (Northeastern Netherlands, D-NL), Fife (Eastern Scotland, F-SC), and the inner Limfjord catchment (Northwestern Denmark, L-DK). Various use options were assessed for three co-product types: manure, crop residues, and household organic waste. In L-DK and D-NL, more manure was available than in A-FR and F-SC, which strongly affected outcomes of the alternative use options. Manure digestion reduced GHG emission (ranging from -2.0 % to -19.8 % across regions), but EOM soil inputs decreased (-1.1 % to -25.3 %) compared to untreated manure. Crop residue use was important in regions with more cereal production (L-DK and F-SC), improving the regional energy balance when digested (+11.1 % to +195.5 %), or increasing EOM inputs when retained (+2.8 % to +15.9 %) compared to residue removal. What happened with household organic waste had less effect on the indicators, because of the small volumes compared to manure and crop residues. Our study suggests that regional context strongly affects the impact of co-product use options on environmental indicators. Prioritization of co-product utilization should mainly consider co-product type and its regional availability.