WASTE AND BIOMASS MANAGEMENT & VALORIZATION Mechanism and role of seeded native grasses to immobilize nitrogen on harvested blanket peat forests for protection of water courses Zaki-ul-Zaman Asam 1,2 & Connie O’Driscoll 2,3 & Mohsin Abbas 1 & Mark O’Connor 3 & Muhammad Waqas 4 & Mohammad Rehan 5 & Abdul-Sattar Nizami 6 & Liwen Xiao 3 Received: 20 April 2020 /Accepted: 26 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Forest harvesting activities on peatlands have long been associated with nutrient leaching and deterioration of downstream water quality. This study aims to assess the effect of grass seeding practice on harvested blanket peatlands to immobilize N and reduce its export to water courses. First, a plot-scale field experiment was conducted by seeding with two grass species (Holcus lanatus and Agrostis capillaris) to study the N uptake potential from a harvested area. Secondly, a simulated rainfall experiment was conducted to study the effect of these grasses on reducing N leaching from surface peat using laboratory flume approach. In the end, the role of seeded grasses in removing N from nutrient-rich throughflow water was assessed using simulated overland flow experiment. The results showed that the seeded grasses had the potential to uptake over 30 kg ha -1 of N in the first year after seeding on harvested peatlands, whereas it takes over 2.5 years to establish the same level of N uptake by natural re-vegetation (non-grassed). In the simulated rainfall experiment, the inorganic N (NH 4 + -N and NO 3 - -N) leaching in surface runoff from grassed flumes was 72% lower (453 mg m -2 ) than non-grassed flumes (1643 mg m -2 ). In the simulated overland flow exper- iment, the N retention by grassed flumes was significantly higher (98%) as compared to non-grassed flumes (70%) in the simulated overland flow experiment. Comparatively higher concentrations of NH 4 + -N and NO 3 - -N in soil porewaters of non- grassed flumes suggest that this N retention by non-grassed flumes is less sustainable and is likely to be leached in runoff in subsequent flow events. The results from all three experiments in this study suggest that seeded grasses are a major sink of N on harvested blanket peatland forests. Immobilization of N onsite using the grass seeding and mini-buffer practice could be an efficient and a feasible mean of reducing N export from harvested blanket peatland forests in order to protect the sensitive water courses. However, the sustainability of retention and immobilization of N by grasses needs to be studied further in long-term field-scale experiments on multiple peatland sites. Keywords Water protection . Peatland . Soil . Grass seedling . Water bodies . N uptake Introduction The deterioration of the water quality of peatland-fed headwa- ters has gained increasing interest in recent years. Often, these headwaters are oligotrophic by nature and feed waters con- taining salmonids and freshwater pearl mussels (one of the most endangered species in the world and protected under the EU Habitats Directive within Special Areas of Responsible Editor: Philippe Garrigues * Zaki-ul-Zaman Asam zaki.asam@uog.edu.pk * Abdul-Sattar Nizami asnizami@gcu.edu.pk 1 Department of Environmental Sciences, University of Gujrat, Gujrat, Pakistan 2 Civil Engineering, National University of Ireland, Galway, Ireland 3 Department of Civil, Structural and Environmental Engineering, Trinity College Dublin, Dublin, Ireland 4 Department of Environmental Sciences, Kohat University of Science and Technology, Kohat, Pakistan 5 Center of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia 6 Sustainable Development Study Centre, Government College University, Lahore 54000, Pakistan Environmental Science and Pollution Research https://doi.org/10.1007/s11356-020-11433-4