Bernou van der Wiel

Spatial decoupling of crop and animal production has changed biomass flows in the agro-food-waste system (AFWS). Currently the system depends on continuous input of non-renewable resources, while nutrients brought into the system are lost to the environment. The spatial decoupling concentrates nutrients through animal feed input in animal production specialized areas. Suboptimal management of biomass flows, such as manure, leads to fertilization beyond crop requirements in areas specialized in animal production causing local environmental issues. Whereas, nutrient depletion in areas supplying feed and a decline in soil organic matter in both occurs. To safeguard future food security, preserve natural resources and reduce environmental stresses, it is imperative to address local nutrient (including C) management in the AFWS. In society and research the concept of nutrient circularity is gaining momentum as strategy to do just that. An indispensable first step to improve nutrient circularity in a local area is to assess the current nutrient flows. Substance Flow Analyses (SFA) give inside into the current nutrient flows. Thereafter, scenario studies provide inside on the expected impact of changes in the AFWS. Systemic change, covering a complete system, requires adaptation of many stakeholders. A participatory approach with SFAs through a bottom-up approach can provide access to otherwise tacit knowledge, including data, and facilitate the, till now lack of, implementation of system changes. The aim of this thesis thus is to identify entry points for restoring local nutrient circularity of the AFWS through utilizing stakeholder input. After the introduction in Chapter 1, Chapter 2 reviews scientific literature on SFA’s of AFWS in local areas aiming to restore local nutrient circularity. Through the review 57 papers were selected that fit the selection criteria. These papers were assessed and the characteristics were summarized. This literature review amongst other results shows that there is no consensus on the optimal spatial boundary to be used for a nutrient stock and flow analysis that aims at restoring local nutrient circularity. The reasons for this is that in practice, it is not the spatial dimensions that govern potential to restore nutrient circularity, but rather the level on which policy is implemented and the structure of the AFWS within the study area. Moreover, a focus on P was found. Local nutrient stock and flow analyses, however, need to include N, P, K and C as they are equally essential for food production, their biological utilization in plants, animals and soils is interdependent (stoichiometry) and they are found in the same biomass. On the basis of the review, a six-step methodical framework such analyses can deploy, is proposed. A field survey exploring the local circumstances should be conducted first to support the choices that have to be made, such as the geographical boundary. Including all subsystems of the AFWS and analyzing N, P, K and C flows simultaneously, facilitates assessment of the full potential to restore local nutrient circularity. The six-step methodical framework makes it possible to identify hotspots, which in turn facilitates the development of measures that can help restore nutrient circularity in the local area. Improved nutrient circularity makes it possible to preserve natural resources, reduce negative effects on the environment and human health locally and globally, and safeguard food security in the long term. The methodical framework proposed in Chapter 2 forms the basis for the SFA in Chapter 3. Chapter 3 quantifies the N, P and K flows throughout the AFWS of the nutrient-saturated area, German district Cleves. For flows of biomass potentially available as fertilizers or soil amendments, the analysis is extended to include C. This paper moreover identifies options to improve the nutrient self-sufficiency of the system as a first step towards nutrient circularity within the district. The results indicate that the primary flows in the AFWS in district Cleves are related to agriculture, especially to animal production. The large imports of feed and inorganic fertilizers and the low levels of nutrients exported in food, illustrate the linear nature of the AFWS in the district and explains the nutrient surplus. Animal production in the studied area was highly dependent on feed import, while the application of manure led to losses to the environment. This study denotes that system change with regard to animal production, namely reducing livestock numbers based on local feed supply, using grasslands and by-products from food processing, could support a more circular AFWS. Through the implementation of technologies for the production of bio-based fertilizers, locally available biomass can replace otherwise imported inorganic fertilizers. While, local recycling is desired to reach a self-sufficient local system and conserve organic C, direct application of biomass results in oversupply of especially P due to imbalanced nutrient stoichiometry of supply and demand. Chapter 3 concludes that future research should aim at balancing crop and animal production and evaluating the potential of technologies for creating bio-based fertilizers to facilitate a more circular AFWS. Chapter 4 carries out a qualitative case study and a practical application of the innovation platform approach in the Dutch-German border region Rhine-Waal. The objective of this chapter was to determine challenges and opportunities in the AFWS towards circular nutrient management in a nutrient-saturated and intensive animal production-dominated localized area. The results indicate that challenges and opportunities exist at three levels: the individual actor’s level, the system level and the interconnection of the system with its wider environment. With a variety of stakeholders from animal and crop production to the food processing industry being present in the study area, the current demand and supply of biomass is very diverse. This diversity is identified as a distinct opportunity for the establishment of a biomass exchange network in the area. However, information on demand and supply of nutrients between actors is currently scattered and information sharing hindered by the lack of direct monetary benefits. The lessons learned using the innovation platform approach are a first step towards improving nutrient circularity at a localized scale in nutrient-saturated areas. Findings from Chapter 4 support the approach with stakeholder participation in Chapter 5. Chapter 5 aims to find socially acceptable solutions for circularity in the AFWS system as measure to reduce nitrogen (N) losses and subsequently prevent environmental damage by combining participatory modelling and scenario SFA. A local perspective on the same case study area as in Chapter 3, the animal production-dominated German district Cleves, is taken. Three scenarios with stakeholder input regarding crop allocation, livestock composition, livestock reduction, and manure allocation, following the elimination of feed imports are analyzed. The results show a limited effect of feed import elimination on N losses if no further measures are taken, such as reduced consumption of animal-based products. Further, the study shows that it is important to improve stakeholders' knowledge about approaches to circular AFWS. The discrepancy between stakeholder visions and N circularity provide policy makers with the recommendation to improve stakeholders' visions of a circular AFWS. Chapter 6 synthesizes the findings of Chapters 2 through 5. The approach in Chapter 5, locally reconnecting crop and animal production, is presented as the first entry point to restoring local nutrient circularity in AFWS. This first entry point reduces the nutrient (expressed as N) losses and improves nutrient self-sufficiency. However, it also shows that reconnecting local feed availability and animal production without further adjustment will shift the dependence from feed import to inorganic fertilizer import. Therefore, technological innovations to recover nutrients from locally available residual biomass to be used as fertilizers, are presented as a second cumulative entry point to restoring local nutrient circularity. This cumulative entry point reduces the nutrient losses and improves nutrient self-sufficiency further. However, the dependency on inorganic fertilizers is still increased compared to the reference year. Lastly, human consumption adaptation is presented as the last cumulative entry point to improving local nutrient circularity. The total protein consumption and the percentage derived from animals are reduced. This cumulative entry point reduces nutrient losses further and reduces the import of inorganic fertilizers compared to the reference year. However, the nutrient self-sufficiency is not improved further. The results show that circularity in itself is not the goal. The cumulative approach, addressing circularity through reconnecting crop and animal production, efficiency through technological innovations to recover nutrients from locally available biomass, and sufficiency through human consumption, reduces nutrient losses and dependency on non-renewable resources.