Risk assessment of replacing conventional P fertilizers with biomass ash: Residual effects on plant yield, nutrition, cadmium accumulation and mycorrhizal status Carla Cruz-Paredes a, ⁎, Álvaro López-García a , Gitte H. Rubæk b , Mads F. Hovmand a , Peter Sørensen b , Rasmus Kjøller a a Department of Biology, Section for Terrestrial Ecology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark b Department of Agroecology, Aarhus University, 8830 Tjele, Denmark HIGHLIGHTS • A conventional fertilizer was compared with biomass ashes. • Barley yield, nutrition, cadmium accu- mulation and mycorrhizal status were evaluated. • P availability was similar for treatments while Cd accumulated only in roots. • Mycorrhizal status was not negatively affected. • The biomass ashes tested can maintain the available P in agricultural soils. GRAPHICAL ABSTRACT abstract article info Article history: Received 27 June 2016 Received in revised form 23 September 2016 Accepted 23 September 2016 Available online xxxx Editor: D. Barcelo Reutilizing biomass ashes in agriculture can substitute inputs of P from finite primary sources. However, recycling of ashes is disputed due to their content of toxic substances such as heavy metals. This study evaluates the poten- tial risk of replacing easily soluble inorganic P fertilizer with P in biomass ashes in a barley crop grown on soil with adequate P status. Two contrasting doses of three different types of ashes were applied to an agricultural field with spring barley and compared to similar doses of triple-superphosphate fertilizer. In the second growing sea- son after biomass ash application, grain, straw and root dry matter yield, and P and Cd uptake were determined. Resin-extractable P was measured in soil and the symbiotic arbuscular mycorrhizal fungal activity, colonization, and community composition were assessed. Crop yield was not affected by ash application, while P-uptake and mycorrhizal status were slightly enhanced with high ash applications. Changes to the mycorrhizal community composition were evident with high ash doses. Cadmium uptake in aboveground plant tissue was unaffected by ash treatments, but increased in roots with increasing doses. Consequently, we conclude that fertilization with biomass ashes can replace conventional fertilizers without risk to barley crops in the short term. © 2016 Elsevier B.V. All rights reserved. Keywords: Fertilization Arbuscular mycorrhizal fungi Phosphorus Barley Cadmium Biomass ash 1. Introduction Biomass ash is a waste product obtained after the incineration of bio- mass fuels for energy production (Karltun et al., 2008). The application of biomass ash to soil offers an alternative for its disposal and for nutri- ent recycling (Patterson et al., 2004). Reutilizing biomass ash in Science of the Total Environment xxx (2016) xxx–xxx ⁎ Corresponding author. E-mail address: carla.paredes@bio.ku.dk (C. Cruz-Paredes). STOTEN-21020; No of Pages 9 http://dx.doi.org/10.1016/j.scitotenv.2016.09.194 0048-9697/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv Please cite this article as: Cruz-Paredes, C., et al., Risk assessment of replacing conventional P fertilizers with biomass ash: Residual effects on plant yield, nutrition, cadmium accu..., Sci Total Environ (2016), http://dx.doi.org/10.1016/j.scitotenv.2016.09.194