Accumulation of nitrous oxide and depletion of oxygen in seasonally frozen soils in northern Japan — Snow cover manipulation experiments

摘要: Abstract It has been suggested that soil-thawing and snow-melting are critical triggers for vigorous emissions of nitrous oxide (N 2 O) from soils in cold regions. However, because soil freezing is affected by air temperature snow cover, accurate predictions estimate subsequent this important greenhouse gas difficult to make. In study, we measured situ N O oxygen (O ) concentrations at two experimental sites northern Japan over the period a year, November 2008 October 2009, clarify factors stimulating production low temperatures. The were N-fertilized bare arable lands with different frost depths snowmelt rates, according cover management imposed. Winter-to-spring net fluxes, ranging −0.10 1.95 kg N O–N ha −1 , positively correlated annual maximum depth (ranging 0.03 0.41 m; r  = 0.951***). plots deeper frost, winter-to-spring fluxes represented 58% 85% values. Soil was stimulated when greater than 0.15 m or daily mean 0.05-m below −2.0 °C. greatest depth, 0.10 m peaked 46 ppm fell down 0.12 m 3  m −3 under 0.0 °C. Snowmelt acceleration had no effect on during period.