title: Recycling potential of secondary phosphorus resources as assessed by integrating substance flow analysis and plant-availability.
abstract: The plant-availability of phosphorus (P) plays a central role in the ability of secondary P resources to replace mineral fertilizer. This is because secondary P plant-availability varies, often with large fractions of residual P that has no immediate fertilization effect. Therefore, if low quality secondary P fertilizers are applied, they will accumulate in soils that, in the long run, may increase the risk of P runoff and eutrophication. Substance flow analyses (SFA), used to identify potentials for improved P management, have not considered this well-known quality barrier. We, therefore, argue that traditional SFA over-estimates the fertilizer potential of secondary P resources. Using Norway as a case, we present a plant-availability extended SFA methodology that integrates SFA and the concept of relative agronomic efficiency. To account for the plant-available soil P stock and long-term soil interactions, we adjust the Norwegian P fertilization demand based on soil P values. We found that, while the method has uncertainties particularly for long-term estimations, it more realistically estimates secondary P fertilizer potentials and is adaptable to other countries. For Norway, we found the overall secondary P fertilizer potential reduced by 6-55% when considering plant-availability. The most important secondary resource was manure, which had the highest P plant-availability and quantities large enough (10.9kt plant-available P/yr) to meet Norway's entire P fertilization demand (5.8kt plant-available P/yr). However, barriers related to its transportability need to be overcome to efficiently use this resource. Fish sludge was also an important product, with 6.1kt plant-available P/yr but with uncertain plant-availability data. We argue that high quality secondary P resources can theoretically meet Norway's P fertilization demand and, therefore, make Norway mineral P independent. However, it is important that their use is carefully regulated based on plant-availability to eliminate the soil accumulation of both available and residual P.
authors.affiliation: Industrial Ecology Programme, Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway. Electronic address: helen.a.hamilton@ntnu.no.
authors.forename: Helen A
authors.initials: HA
authors.lastname: Hamilton
authors.affiliation: Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, 1431, Ås, Norway; Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway.
authors.forename: Eva
authors.initials: E
authors.lastname: Brod
authors.affiliation: Industrial Ecology Programme, Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway; Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, 1431, Ås, Norway.
authors.forename: Ola
authors.initials: O
authors.lastname: Hanserud
authors.affiliation: Industrial Ecology Programme, Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Müller
authors.affiliation: Industrial Ecology Programme, Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
authors.forename: Helge
authors.initials: H
authors.lastname: Brattebø
authors.affiliation: Norwegian Institute of Bioeconomy Research (NIBIO), P.O. Box 115, 1431, Ås, Norway.
authors.forename: Trond K
authors.initials: TK
authors.lastname: Haraldsen
keywords: Phosphorus; Phosphorus fertilization demand; Plant availability; Relative agronomic efficiency; Substance flow analysis