For arable soils, it is not clear whether closing a controlled drainage system leads to P mobilization due to water table rise and associated changes in redox-induced biogeochemical processes. Therefore, we investigated P mobilization at different redox conditions using three spring barley (Hordeum vulgare L.) cropped lysimeters filled with monoliths of arable northeastern German soil profiles. Pore water samples were collected weekly from three different depths, and dissolved (<0.45 μm) element concentrations of total C, P, Al, Fe, Mn, Ca, Mg, and K, as well as inorganic and organic C (DIC and DOC) and P (P i and P o), SO 4 2−-S, and NO 2 −-N and NO 3 −-N were determined. The total P concentration in pore water collected from a given lysimeter at a given time was 1.8 mg P L − 1 maximum. Organic P concentrations in subsoil solutions were positively correlated with Fe concentrations. Grain yield of spring barley ranged between 5.6 and 6.5 Mg ha − 1, and total biomass P uptake was negatively correlated with the stable P stocks of the soil profiles. Results suggest that reductive conditions in subsoils led to dissolution of pedogenic Fe-(oxy)hydroxides and release of P o compounds, the latter of which were more important for biomass P uptake than P released from stable P compounds. Overall, closing the drainage at the field site could represent a moderate P mobilization risk, which would probably be lower compared with a P mobilization risk caused by a heavy rainfall event. Abbreviations: DIC, dissolved inorganic carbon; DOC, dissolved organic carbon; DRW, drying and rewetting; Eh, redox potential; ICP-OES, inductively coupled plasma-optical emission spectroscopy; P i , inorganic phosphorus; P o , organic phosphorus; PVC, polyvinyl chloride; TC, total carbon. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Within this work a method how to analyze the recycling sites in Rostock and the surrounding municipalities is presented. The approach is embedded into the project Prosper-Ro and is part of the development of a decision support system for planning purposes in the mentioned region. The recycling sites are one part of the project and in focus to tackle the challenge of transforming the linear economy to a circular economy. To make the method easy adoptable, it incorporates free available data, like Open Street Map and governmental data, such as ALKIS, to derive a high resolution dataset for the population density as well as the potential waste. This leads to an easy adoptable approach for other municipalities. With Open Street Map and QGIS routing software QNEAT it was possible to create reachability areas for each recycling site in respect to the customer and waste potential. These data lead to a parameter of 250 customers per 1 m 2 of container area in the city area of Rostock which is useful for planning new sites or extending the existing ones. The derived data could be verified by the help of a survey, which shows that the customers in Rostock are mostly satisfied with their recycling sites and want to improve the transformation to an circular economy, for instance by the reuse of electrical devices.