Phosphate rock is a non-renewable source of phosphorus (P) in mineral fertilizer and many countries need to use P fertilizer more efficiently in food production. This study explored the theoretical fertilizer potential of the P-rich bioresources animal manure and sewage sludge to supply the required P fertilizer for crops. We used Norway as a case study and employed multi-regional substance flow analysis with averaged annual data for the period 2009–2011. In a status quo soil balance for agricultural soil, all counties had a positive balance with a national average of 8.5 (range between counties of 2.7–14.7) kg P ha⁻¹. In addition, two fertilizer regimes (FR) were evaluated for the period; FR1 omitted mineral P fertilizer from the balance and assumed bioresource addition matched plant P offtake regardless of soil available P, while FR2 omitted fertilizer from the balance and adjusted bioresource inputs according to whether soil available P was above (adjusted downwards) or below (adjusted upwards) the optimum soil P level. FR1 and FR2 gave a national average P surplus of 1.2 (range −7.0 to 11.2) and 6.2 (range −2.5 to 19.0) kg P ha⁻¹, respectively. The secondary P fertilizer potential of bioresources for meeting P requirements was found to be underestimated in the short term by not taking into account the actual plant-available soil P level. Our conclusion was that the P fertilizer values of manure and sludge have the theoretical potential to meet the P fertilizer requirements of all Norwegian crops assessed in both the short-term and long-term perspective.

Specialized agricultural production between regions has led to large regional differences in soil phosphorus (P) over time. Redistribution of surplus manure P from high livestock density regions to regions with arable farming can improve agricultural P use efficiency. In this paper, the central research question was whether more efficient P use through manure P redistribution comes at a price of increased environmental impacts when compared to a reference system. Secondly, we wanted to explore the influence on impacts of regions with different characteristics. For this purpose, a life cycle assessment was performed and two regions in Norway were used as a case study. Several technology options for redistribution were examined in a set of scenarios, including solid–liquid separation, with and without anaerobic digestion of manure before separation. The most promising scenario in terms of environmental impacts was anaerobic digestion with subsequent decanter centrifuge separation of the digestate. This scenario showed that redistribution can be done with net environmental impacts being similar to or lower than the reference situation, including transport. The findings emphasize the need to use explicit regional characteristics of the donor and recipient regions to study the impacts of geographical redistribution of surplus P in organic fertilizer residues.

To effectively navigate out of the climate crisis, a new interdisciplinary approach is needed to guide and facilitate research that integrates diverse understandings of how transitions evolve in intertwined social–environmental systems. The concept of tipping points, frequently used in the natural sciences and increasingly in the social sciences, can help elucidate processes underlying major social–environmental transitions. We develop the notion of interlinked ‘social–climatic tipping points’ in which desirability and intentionality are key constitutive features alongside stable states, feedbacks, reversibility and abruptness. We demonstrate the new insights that our interdisciplinary framework can provide by analysing the slowdown of the Atlantic Meridional Overturning Circulation and associated flooding of the Ahr Valley in Germany as a social–climatic tipping point. This framework can enable more sustainable and equitable futures by prioritising social–climatic tipping points for interdisciplinary research, identifying opportunities for action, and evaluating the nuanced desirability and acceptability of proposed solutions. Read the free Plain Language Summary for this article on the Journal blog.