The effects of organic fertiliser, arginine, on the chemical composition of soil organic matter in a boreal forest

There is a growing body of evidence that plants uptake a monumental amount of organic forms of nitrogen (N) like amino acids in addition to those in inorganic forms. An amino acid-based fertiliser has been shown to improve seedling development and commercialised. Boreal forests store a substantial amount of carbon (C) in the soil and this is widely known to be further enhanced by the addition of inorganic nitrogen fertiliser via hampered decomposition. However, very little is known about how amino acid-based fertiliser influences C/N cycling in the boreal soils. The organic forms of N supply not only nitrogen but also carbon. If the previously demonstrated suppression of SOM decomposition is owing to altered C:N ratios in substrates, the amino acid-based fertiliser may not have as pronounced effects on the soil as the inorganic fertiliser. 

 We have examined the impacts of the organic fertiliser (100 kg N and 130 kg C ha^-1 year^-1)—arginine—on the chemical composition of soil organic matter in a boreal forest in comparison to non-fertilised, inorganic fertilised (ammonium-nitrate) and C-controlled inorganic fertilised (sucrose + ammonium-nitrate) conditions. The soil organic matter was characterised using two metrics: pyrolysis GC/MS and 13C solid-state nuclear magnetic resonance (NMR), combined with enzymological and metagenomic analysis.

We will be presenting the results following 4-year of the fertiliser treatments. Preliminary results have shown that there is limited evidence that the fertiliser treatments alter soil C/N cycing in four years. Nevertheless, the chemical composition in SOM under the organic fertiliser condition was similar to that under C-controlled compared to inorganic fertiliser treatment.