Traditionally, the ever-increasing global demand for food was met by expanding and intensifying agricultural production. However, these practices led to significant environmental impacts. Today, the food value chain is responsible for considerable amounts of greenhouse gas emissions (approximately 26% of global anthropogenic emissions) and eutrophication (approximately 78% of global emissions).

The EU project “Circular Agronomics” therefore aims to evaluate practical and technical solutions for improving the current carbon, nitrogen, and phosphorus cycles in European agricultural systems using life cycle assessment. The project comprises six case studies from different regions of the European Union (Catalonia, Brandenburg, Lungau, Emilia-Romagna, Gelderland, and South Moravia) in which ten different experiments were conducted to test the practical and technical solutions.

The experiments were then assigned to three strategies targeting different areas of agricultural production:

• Nutrient management in plant production
• Nutrient management in animal production
• Waste management and nutrient/carbon recovery

Nutrient management in plant production

This strategy comprises three experiments investigating various management parameters to increase nutrient efficiency in crop production. The results show that higher nitrogen fertilization leads to higher yields but also increases emissions, a phenomenon even more pronounced in a dry climate. Regarding the timing of fertilization, the lowest emissions were observed four weeks after sowing, which can be explained by the higher nitrogen demand of the plants at this stage. Furthermore, a test of different tillage regimes revealed that the minimal tillage variant is the most favorable in terms of environmental impact per kilogram of harvested crop.

Nutrient management in animal production

This strategy was supported by two experiments, one of which demonstrated the positive effects of precision feeding on reducing greenhouse gas emissions and eutrophication due to needs-based nutrient supply. Furthermore, the second experiment showed that extensive management of organic dairy farms can be very efficient with regard to eutrophication if the management intensity corresponds to the natural production potential of the farm's agricultural land.

Waste management and nutrient/carbon recovery

The remaining five experiments investigated improvements in waste management and nutrient/carbon recovery through the use of waste streams as potential nutrient sources. Of the three digestate treatment concepts examined, microfiltration/microsieving showed the lowest environmental impact. Regarding nutrient recovery, struvite technology can recover nutrients with comparatively low environmental impact and subsequently recycle them. Membrane technology appears to be an energy-efficient alternative to centrifuges for whey separation for carbon sequestration.