The Azolla Filiculoidis is a subtype of aquatic fern species that thrives on fresh surface water bodies, and has a nutritive profile similar to soybean. In this thesis research, it was examined to what extent the large-scale implementation of Azolla-based livestock feed production will affect the future environmental sustainability performance of the Dutch livestock feed sector, in the context of the transition to a circular agricultural system (CAS). To that end, two novel, circular, Azolla-based feed production systems (FPSs) were designed as alternatives to the incumbent, linear, soy-based FPS. Subsequently, these FPSs were combined into three feed production scenarios: a business-as-usual (BAU) scenario which primarily relies on soy, as well as a local farming project (LFP) and a regional supply chains (RSC) scenario, in which the Azolla-based FPSs become dominant by 2050. The environmental impacts of each scenario were quantified in an ex-ante life cycle assessment (LCA), using the Activity Browser (AB) modelling tool. It appeared that, under the given assumptions, the LFP and RSC scenarios perform substantially better on all included environmental indicators by mid-century. This study opens the way for more profound future-oriented environmental modelling research, and recommends follow-up research on the biogeochemical carbon cycle of agro-industrial production systems in an LCA context, the development of fore- and background data for (circular) feed production, and the advancement of the AB software tool.

Malnutrition is worsening, affecting every country and over 3 billion people. There is evidence that rising CO2 levels will not only indirectly increase malnutrition through climate change effects, but also directly through a downshift in the plant ionome, reducing nutritional quality and increasing hidden hunger. Attempts to calculate the human health impact have been conducted with limited statistical power on a small group of nutrients. The impact on different age-sex groups, countries, and nutrients is still largely unknown. This research aims to fill this gap, creating a meta-analysis of the most data (5,809 entries), crops (43), and elements (31 plus phytate) of any study to date, resolving a methodological gap for disharmonious data and applying this to the GENuS model of global nutritional supply in 2011 for eight nutrients (calcium, copper, iron, magnesium, phosphorus, potassium, protein, and zinc) to see which countries will be able to provide enough nutrients for their citizens in a 550 ppm world compared to at 350 ppm. Bootstrapping reveals a distinct 5% to 12% systemic downshift in the plant ionome. Both C3 and C4 plants respond, disproving the hypothesis that C4 plants are mostly unaffected by CO2 rise and supporting the idea that the CO2 saturation point is not directly linked to mineral uptake.  Elements have a differential response, suggesting that the carbon dilution theory is an inappropriate explanation. Zinc, protein, and iron have the largest decreases, and zinc in chickpeas decreases the most (40%) of all groups. Grains (wheat and rice) and soybeans are the hardest hit crops, decreasing in nutritional value up to 12%. The total nutrient supply decreases by 2.3% to 6.4%, increasing the malnourishment and obesity double burden. Countries will no longer provide enough nutrients from food solely due to changes in the plant ionome, impacting every country. Half of the world will develop new deficiencies. The strongest predictor of resiliency to nutritional changes from CO2 rise is diet diversity. Exacerbating global inequality, the impact will be particularly pronounced in African and Asian countries, and among women aged 25-29 compared to men of the same age group and children aged 0-4 years. Changing plant stoichiometry will have dramatic global implications for hidden hunger, worsening or introducing deficiencies, especially in iron, phosphorus, potassium, and zinc.

Food forests have recently received an increasing amount of attention since they are seen as a possible addition to the Dutch nitrogen-sensitive agricultural sector. Food forests are claimed to positively affect local ecosystem services while producing food for human consumption. Most of the effects and the edible production, however, lack scientific and quantified substantiation. This study aims at quantifying the edible production of food forests in the temperate climate zone, compares it to conventional agricultural systems, and analyses factors that may influence the edible productivity. By monitoring 22 100 m2 plots in eight food forests in the Netherlands and Belgium, it was found that the average food forest of this set of food forests produces 1038 kg edible biomass, 948,344 kcal, 12.39 kg proteins, 104.59 kg carbohydrates, and 22.13 kg fats per hectare. except for carbohydrates in conventional hazelnut production and fats in conventional red and black currant production, the food forests’ edible production, consisting of a diverse set of fruits, turned out to contain significantly lower amounts of energy, proteins, carbohydrates, and fats than conventional apple, pear, red currant, black currant, hazelnut, and dairy production in the Netherlands. Furthermore, no significant relationships were found between age, species richness, or canopy cover and the edible production of the food forests. Management and design, however, are considered factors that likely affect the edible production and need to be analysed in future work. Although food forests have not turned out to be competitive with conventional production systems in terms of edible production, they have many more beneficial characteristics than food production alone. More than conventional agricultural systems, food forests are expected to contribute to biodiversity, carbon capture, natural habitat creation, and soil formation and offer possibilities for social aspects like local community building and education. They are therefore still considered a valuable addition to the Dutch agricultural sector, although less productive and with fewer financial incentives, but more in line with nature-inclusive and circular forms of agriculture and with more focus on social opportunities.