SoilSoc Research

Research projects Thesis abstracts

Biogeochemistry of Icelandic Andosols

Institute / Organisation / Unit: University of Aberdeen (www.abdn.ac.uk) and the Agricultural University of Iceland (www.hi.is).

Research director / Project Leader: Dr. Graeme Paton University of Aberdeen and Dr. Olafur Arnalds Agricultural University of Iceland.

PhD responsible: Rannveig Anna Guicharnaud (PhD completed in June 2009).

Keywords: Icelandic Andosols biochemistry. Soil carbon pools. Soil nitrogen pools. Soil microbial activities.

Discription: Studying biological parameters of northern latitude soils is of importance because of their high capacity to sequester organic matter. A consequence of climate change and the resulting increasing temperatures in the Arctic may be the shift from such soils being carbon sinks to becoming unmanageable carbon sources. Despite the relative harshness of the climate and the limited growing season, Icelandic soils are productive when cultivated and there is evidence of the emergence of a warmer and wetter climate. A key issue will be a consideration of the impact of intensive cultivation on the soils, landscape and general environmental parameters. This thesis studied the effect of climate, land use, fertilisation and soil pedological properties on Icelandic Andosols biology. Icelandic agricultural soils biological parameters were affected by land use were fertilisation seamed to suppress nitrogen mineralisation in cultivated fields. Furthermore, there were indications that an increase in soil moisture content promoted either nitrogen immobilisation or denitrification limiting inorganic N availability to the standing vegetation. They were adapted to perform around the freezing point. Soil respiration and enzymatic activities were measured down to a soil temperature of -10C. Around the freezing point enzymatic activities and soil respiration was governed by availability of labile carbon. The soil microbial biomass carbon pool was not affected by different climatic variables (rainfall, air and soil temperatures) or fertilisation treatments. In comparison to other soils sampled in Scotland, Icelandic soils had a considerably larger microbial biomass carbon pools but their biological activity was significantly lower. This was mainly related to their pedological properties promoting high carbon sequestration and low C availability to microorganisms.