Use of by-products as system innovation: GeNeSys Closing cycles through composting Viaene J., Reubens B., Vandecasteele B., Willekens K., De Neve S. Plant Sciences Unit, Institute for Agricultural and Fisheries Research (ILVO), Burgemeester Van Gansberghelaan 109, 9820 Merelbeke, Belgium Contact: 1.How can we valorize insufficiently utilized by-products from the agricultural, horticultural and nature-management sector, possibly in combination with by- products from other sectors? 2.Which approach for biomass enables embracing the complex network of European regulations (Nitrate Directive, Biomass Action Plan, code of good ground care, …)? 3.How can we maintain or increase productivity of soil and crops, retain the soil organic matter, and at the same time avoid groundwater pollution? 4.How can we improve the closure of nutrient and material cycles and decrease the dependency on external inputs (mineral fertilizer, pesticides, cultivation substrate, …) without considerably increasing costs? Outstanding, high quality designer compost is part of the solution because: part of the biomass and nutrients are recycled  more efficient use of production resources compost characteristics fit the expectations of the end-user composting reduces volume and size of the feedstock  facilitates transport and application compost contributes to the supply of effective organic matter nutrients in compost are released slowly  prevents nutrient leaching the mix of organisms in compost  improves soil in biological terms long term application of compost can improve the disease resistance of the soil high temperatures during the process  suppresses weed seeds and germs But despite the numerous advantages: several technological, logistic, organizational, social, legal and economical stumbling blocks need further investigation wide variations in potential feedstock materials and composting circumstances can lead to variations in composition and characteristics of the compost every industry sector needs a specific product to meet its needs As a result, possibilities are underutilized and innovations are not always put into practice. Challenges Research approach Aim: Development of qualitatively outstanding, economically feasible compost products for various applications in agriculture and horticulture in Flanders transdisciplinary and participatory research involving all relevant stakeholder groups (farmers, horticulturists, compost sector, nature sector, scientists, policymakers, etc.) possibilities to incorporate underutilized, often more difficult, ‘green’ by-products from vegetables, discards, manure possibilities to cooperate with nature-management sector for ‘brown’ by-products (wood chips, clippings, sod cuttings, …) Focus: How can we follow up and adjust the composting process (e.g. mass balance, material losses, microbial activity, hygiene)? How can we standardize the quality of the compost products developed in function of the needs of the end-user (e.g. nutrient content and availability, organic matter, biology, presence of pathogens and heavy metals)? How can we obtain a maximum applicability of the compost products (e.g. impact on crop development and health, soil characteristics and processes)? What are the advantages and disadvantages of different scenarios: large-scale vs. on-farm composting, type of composting, …? Strategy: First: Roadmap for scope-definitionDouble-loop process 1. Exploratory research on selected by-products 2. Up-scaling of best valorization pathways