Nitrous oxide emissions from agricultural soils at low temperatures: a laboratory microcosm study

• Published in: Soil biology & biochemistry 2004-05, Vol.36 (5), p.757-766
• Main Authors: Koponen, Hannu T, Flöjt, Laura, Martikainen, Pertti J
• Format: Article
• Language: English
• Subjects: Agricultural soils; Agronomy. Soil science and plant productions; Biochemistry and biology; Biological and medical sciences; carbon dioxide; Chemical, physicochemical, biochemical and biological properties; CO 2; freeze-thaw cycles; Freezing–thawing; Fundamental and applied biological sciences. Psychology; gas emissions; N 2O emissions; nitrous oxide; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; soil temperature; Temperature; textural soil types
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2003.12.011

We studied in laboratory microcosms (intact soil cores) N 2O and CO 2 emissions from four different agricultural soil types (organic soil, clay, silt and loam) at low temperatures with or without freezing–thawing events. When the temperature of the frozen soil cores was increased stepwise from −8 °C the N 2O emissions began to increase at −0.5 °C, and peaked at −0.1 °C in the organic, clay and silt soils, and at +1.6 °C in the loam soils. However, a stepwise decrease in soil temperature from +15 °C also induced an increase in the N 2O emissions close to the 0 °C. These emissions peaked between −0.4 and +2.5 °C depending on the soil type and water content. However, the emission maxima were from 2 to 14.3% of those encountered in the experiments where frozen soils were thawed. Our results show that in addition to the well-documented thawing peak, soils also can have a maximum in their N 2O emission near 0 °C when soil temperature decrease. These emissions, however, are less than those emitted from thawing soils. The correlations between the N 2O and CO 2 emissions were weak. Our results suggest that N 2O is produced in soils down to a temperature of −6 °C.