Intensive slurry management and climate change promote nitrogen mining from organic matter-rich montane grassland soils

• Published in: Plant and soil Vol. 456; no. 1-2; pp. 81 - 98
• Main Authors: Schlingmann, Marcus, Tobler, Ursina, Berauer, Bernd, Garcia-Franco, Noelia, Wilfahrt, Peter, Wiesmeier, Martin, Jentsch, Anke, Wolf, Benjamin, Kiese, Ralf, Dannenmann, Michael
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2020; Springer
• Subjects: Biomedical and Life Sciences; Carbon content; Cattle; cattle manure; climate change; Closed ecological systems; Ecology; Environmental aspects; Global temperature changes; Grasslands; International economic relations; Labeling; land use; Life Sciences; Mesocosms; Mineral industry; mineralization; Mining industry; nitrogen; nitrogen fertilizers; nutrient use efficiency; phytomass; Plant Physiology; Plant Sciences; Regular Article; risk; slurries; soil organic matter; Soil Science & Conservation; Soils; Tracers (Chemistry); Germany; N tracing; Productivity; Nitrogen use efficiency; Nitrogen balance; Grassland soils; Slurry fertilization
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-020-04697-9

Aims Consequences of climate change and land use intensification on the nitrogen (N) cycle of organic-matter rich grassland soils in the alpine region remain poorly understood. We aimed to identify fates of fertilizer N and to determine the overall N balance of an organic-matter rich grassland in the European alpine region as influenced by intensified management and warming. Methods We combined 15 N cattle slurry labelling with a space for time climate change experiment, which was based on translocation of intact plant-soil mesocosms down an elevational gradient to induce warming of +1 °C and + 3 °C. Mesocosms were subject to either extensive or intensive management. The fate of slurry-N was traced in the plant-soil system. Results Grassland productivity was very high (8.2 t - 19.4 t dm ha −1  yr −1 ), recovery of slurry 15 N in mowed plant biomass was, however, low (9.6–14.7%), illustrating low fertilizer N use efficiency and high supply of plant available N via mineralization of soil organic matter (SOM). Higher 15 N recovery rates (20.2–31.8%) were found in the soil N pool, dominated by recovery in unextractable N. Total 15 N recovery was approximately half of the applied tracer, indicating substantial loss to the environment. Overall, high N export by harvest (107–360 kg N ha −1  yr −1 ) markedly exceeded N inputs, leading to a negative grassland N balance. Conclusions Here provided results suggests a risk of soil N mining in montane grasslands, which increases both under climate change and land use intensification.