H2020 Circular Agronomics project: efficient carbon, nitrogen, and phosphorus cycles in the European agri-food system and related upstream and downstream processes to mitigate emissions

At AC, an innovative approach (hyperspectral imaging) has been used to assess various soil chemical properties in an undisturbed, unmixed state at ultra-high resolution (~60 μm per pixel), enabling more sensitive analysis of soil profile changes. This has significantly improved our understanding of soil amendments in relation to carbon sequestration. AC has developed a novel approach that combines post-planting (inter-row) application of organic fertilizer with nitrification inhibitors. This combination has enabled cost-effective adjustment of nutrient availability and plant demand. Microfiltered digestate for fertigation (MDF) has proven to be a promising prototype for the direct use of liquid digestate for fertigation with drip irrigation lines, increasing nutrient use efficiency, reducing emissions, and minimizing water consumption. MDF has lower energy demands and is lower cost than membrane filtration. A new solar drying system has been developed to produce bio-based fertilizers.

In intensive dairy farming, CA has promoted the use of precision feeding systems in dairy cows to tailor nutrients to their needs and thus reduce nitrogen excretion in manure and greenhouse gas (GHG) emissions by improving feed efficiency.

Furthermore, as part of the CA research focus, the isolation of potential bacteriophages has been investigated to control the number of ammonia-producing bacteria in the rumen of dairy cows. In extensive dairy farms, the CA focuses on cow physiology and compares different feeding strategies through the respiration chamber, which has made it possible to combine not only feeding with nutrient cycles, but also with gases and GHG emissions, studying the entire nutrient flow. Whey has been separated using innovative electrospun nanofibrous membranes, compared to recent technologies (ultrafiltration, reverse osmosis), with additional concentrate treatment (polishing, drying) for the sweet and sour whey food industry. The acid whey products will no longer be wasted but will be reused in livestock and agriculture. We have developed a novel nitrogen recovery technology, which can be integrated into existing biogas plants using sidestream treatment. Vacuum degassing can process mixed phases (solids and liquids; it does not require filtration or other excessive pretreatment), requires no additional heat, and is therefore more economical than stripping. A novel treatment using commercial enzymes has been developed to stimulate the release of phosphate from phytic acid. The process is flexible and adaptable to the treatment of residues and wastewater from soybean processing plants.

The project has a direct impact at the political/legal, environmental, social, technological, and economic levels. CA has contributed to the development of effective, collaborative policymaking by providing clear, evidence-based policy recommendations that will help policymakers identify policy barriers to closing nutrient cycles. Furthermore, the project has provided new input into CAP improvement debates, as our cutting-edge research has promoted new thinking in policymaking, for example, on the perception of the important role of carbon in agriculture, as well as on the risk vs. possibility debates related to the use of bio-based residues. CA has developed affordable technical solutions that fit into the current structures of European agriculture, minimizing the economic pressure on producers within the European agricultural sector to keep food production costs stable. The societal analysis within WP4 has led to the development of non-technical measures, such as policy actions, towards greater adequacy in agriculture, food consumption, and waste management.