Title: Phosphorus availability following revegetation with Nootka Lupine at two contrasting sites in Iceland

Phosphorus scarcity is one of the major global environmental challenges. Understanding how phosphorus can be recovered is important for a sustainable future. The objectives of this study were to (i) assess if Nootka lupine, a nitrogen fixing legume, mobilizes phosphorus in Icelandic soils, and (ii) to provide insights into methods that are used to recover and reuse phosphorus. This was done to effectively test the hypothesis suggested in this study; that if Nootka lupine mobilizes soil phosphorus, there would be more phosphorus availability at sites colonised by Nootka lupine as compared to control sites. Soil samples and vegetation biomass data were collected at randomly selected sites colonized by Nootka lupine and control sites at Gunnarsholt and Holasandur, Iceland. Soil samples were analysed for plant-available phosphorus using the Bray method. Other measurements included total phosphorus, total iron, total aluminium and soil physical properties. Biomass was determined by oven dried vegetation samples. Data were analysed using ANOVA and Pearson correlation. The results showed that Nootka lupine sites had significantly (p < 0.05) higher plant-available phosphorus compared to the control sites, which implies that Nootka lupines mobilize phosphorus in Icelandic Andosols and therefore increase plant-available phosphorus. This study thus concluded that Nootka lupine mobilizes soil phosphorus; a potential cost effective method for mobilizing phosphorus for other plants in the ecosystem.