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Research article2015Peer reviewed

Ash as a phosphorus fertilizer to reed canary grass: effects of nutrient and heavy metal composition on plant and soil

Lindvall, Eva; Gustavsson, Anne-Maj; Samuelsson, Robert; Magnusson, Tord; Palmborg, Cecilia

Abstract

Fertilization effects and risks of heavy metal enrichment were studied in a field experiment, in which plots of reed canary grass (RCG) were treated annually with three different fertilizers: Ash from co-combustion of RCG and municipal wastes (mixed ash), pure RCG ash, and commercial fertilizer (control). RCG ash is a waste product that is currently expensive to dispose of. The amounts of nutrients applied annually were 100kgha(-1)N, 15kgha(-1) P, and 80kgha(-1)K in all treatments. In the ash treatments, all P derived from ash, whereas N and part of the K were supplemented by fertilizers. The amount of heavy metals exceeded the limits set by the Swedish Environmental Protection Agency for all elements analyzed in the mixed ash and for Ni and Cr in the RCG ash. There were no significant differences between treatments in terms of RCG dry matter yield obtained at harvest in spring, or in heavy metal concentrations in the biomass. Soil samples from 0-5cm, 5-10cm, and 10-20cm below the surface showed significant differences between treatments for the concentration of Cd, Cr, Cu, Pb, and Zn, with higher concentrations in plots fertilized with mixed ash than in the control. Neither spring yield nor soil available P was reduced by using ash instead of mineral P fertilizer, suggesting that pure RCG ash can be used to complement commercial fertilizer, albeit less frequently than here. However, ash derived from co-combusting RCG with different waste materials (mixed ash treatment) should not be used in RCG production due to the high heavy metal content.

Keywords

ash fertilization; element balance; heavy metals; Phalaris arundinacea; reed canary grass; spring harvest

Published in

GCB Bioenergy
2015, Volume: 7, number: 3, pages: 553-564

      SLU Authors

    • Lindvall, Eva

      • Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences

      • Gustavsson, Anne-Maj

        • Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences