| Summary: | Wetlands provide a natural environment for nutrient attenuation; however, these ecosystems may also be used as a source of nutrients for soil fertilisation. Anaerobic digestion (AD) of mown plants from wet areas is a promising option to solve the problem of harvested biomass, while the digestate produced during the AD process can be a valuable nitrogen (N) fertiliser. An incubation experiment was run to investigate the effect of fertilising with digestates produced from four wetland plant species (reed sweet-grass, common reed, tufted sedge, reed canary grass) on inorganic-N dynamics in arable soil typical for the region. The amount of N in all digestates was similar and ranged from 46.8 ± 5.6 to 61.5 ± 3.1 g kg-1 (dw). The inorganic-N concentration in the soil increased during the first two weeks, mainly due to a reduction in NH4-N. Rapid NO3-N production led to the amount of NO3-N almost doubling as a result of fertilisation. In all amended soils the N dynamics were similar and did not differ from those in soil fertilised with digestate derived from maize. The incorporation of N from biomass harvested in wetlands into soils on the adjacent arable land could play an important role in the N cycle of a swampy river valley landscape by reducing the need for additional N inputs and thus reducing the transfer of N from agricultural uplands to the river.
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