A regional-scale soil phosphorus balance for exploring mineral fertilizer substitution potentials – the case of Norway Ola Stedje Hanserud 1,2, Eva Brod 1,3 and Helge Brattebø 2 1.Norwegian Institute for Agricultural and Environmnental research (Bioforsk) 2.Industrial Ecology Programme, Norwegian University of Science and Technology (NTNU) 3.Norwegian University of Life Sciences (NMBU)

Main objective Identifying the theoretical potentials for substituting mineral P fertilizer with P-rich waste sources, using Norway as a case study, disaggregated into its 19 counties

Method Substance flow analysis (SFA) Annual averages for Main P flows to and from agricultural soil, converted to tons of P

National aggregate numbers

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t P/yr Manure as only input

t P/yr Manure as only input

t P/yr Manure as only input 10 negative counties

t P/yr Inputs: Manure Meat and bone meal Full wastewater potential 4 negative counties

Regional importance of wastewater P (tons P/yr) Inputs Output Animal manure Wastewater, potential Meat and bone meal Total withdrawal (yield + losses) Share wastewater of total withdrawal Norway % Oslo & Akershus % Sogn og Fjordane %

Assumptions Manure and wastewater P distributed within each county to substitute mineral P Balanced fertilization of crops (input = output) → overestimation of needed input 100% plant available P in meat and bone meal and manure

Wastewater P plant availability 1.Treatment method with certain treatment effect → total amount P in sludge 2.Total amount of P in sludge → plante available P given treatment method Treatment methodTreatment effect (%) 1 P-efficiency (%)* Chemical (average: 25) 2 Biological Chemical-biological (average: 25) 2 Mechanic15100 * Compared to plant availability of mineral P fertilizer 1 Berge & Mellem 2012, 2 Øgaard 2013, 3 Krogstad et al. 2004

Quantification plant availability RegionTot-P in sludge (t/yr) Plant available P (t/yr) P-efficiency (%) North sea counties Rest of the country Whole country Potential for mineral P substitution with todays technology:510 t P/yr Potential for mineral P substitution with new technology: 2700 t P/yr

Conclusions Regional soil P balances indicate substitution potentials Great theoretical potential in replacing mineral P fertilizer Plant availability of recovered wastewater P differs with technology/infrastructure Needs to be followed up with study of feasibility – Technical/economic/environmental – Social acceptability – Drivers (prices/costs, legislation, targets)