Relationship between N_2O and NO emission potentials and soil properties in Japanese forest soils(Environment)

概要

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To determine the relationship between nitrous oxide (N_2O) and nitric oxide (NO) emission rates and soil properties in forest soils, N_2O and NO emission rates in soils were measured in incubation experiments under standardized temperature and water conditions (water content at a water-holding capacity of 60%) using soils packed into a cylindrical core, and variations in the soil properties were also determined. The N_2O emission rates from nitrification and from denitrification were determined separately using a nitrification inhibitor (10Pa acetylene). Soil samples were taken from 25 forest stands in a central temperate area of Japan. The N_2O and NO emission rates were highly variable, even under the standardized temperature and water-holding capacity (60%) conditions. According to a partial least squared regression model analysis, the C:N ratio and pH strongly affected the N_2O emission rate, whereas NO_3^-, water-soluble Al and the C:N ratio strongly affected the NO emission rate. The C:N ratio negatively affected the emission rate of both N oxide gases, suggesting that N mineralization is an important factor in the rates of N oxide gas emission. The acetylene inhibition experiment showed that N_2O emission from denitrification was positively affected by pH, water-filled pore space and filling density, and negatively affected by the C:N ratio, total carbon and total nitrogen.