open access

https://hdl.handle.net/2115/46869

Effects of environmental factors on temporal variation in annual carbon dioxide and nitrous oxide emissions from an unfertilized bare field on Gray Lowland soil in Mikasa, Hokkaido, Japan

英語

temporal variation

2010-08

Blackwell Publishing

Soil Science & Plant Nutrition

56(4)

663-675

Soil is one of the important sources of atmospheric carbon dioxide (CO2) and nitrous oxide (N2O). Studies of CO2 and N2O emission from bare soil may explain the annual change of carbon (C) in soil organic matter (SOM) and help analyzing the N2O production from SOM. Therefore, CO2 and N2O emissions associated with the decomposition of SOM from bare soil are important factors for assessing the C budget and N2O emission in agricultural field. We conducted a study over seven years to assess the controlling factors of CO2 and N2O emissions from unplanted and unfertilized soil in Mikasa, Hokkaido, Japan. Carbon dioxide flux increased in the summer, and there were significant positive correlations between the CO2 flux and soil temperature in the first four years. However, apparent relationships between CO2 flux and WFPS, soil NH4 and NO3 concentrations were not observed. The slope of monthly CO2 emission against mean monthly temperature was positively correlated with monthly precipitation. These results suggest that the response of CO2 production to increase in soil temperature becomes more sensitive in wet soils. The average CO2 emission during the study period was 2.53 Mg C ha^[-1] year^[-1], and uncertainty of the annual CO2 emission was 24%. Annual precipitation explained the yearly variation (CO2 emission [Mg C ha^[-1] year^[-1]] = 0.0021 x annual precipitation [mm year^[-1]] -0.0499, R = 0.976, P < 0.001). Nitrous oxide flux increased from July to October, and was positively correlated with CO2 flux. Based on the ratio of N2O-N : NO-N of fluxes, N2O appeared to be the main product of denitrification. The average N2O emission in the study period was 4.88 kg N ha^[-1] year^[-1], and uncertainty of annual N2O emission was 58.5%. Strong relationships between the monthly emissions of CO2 and N2O suggest that N2O production by denitrification is strongly affected by SOM decomposition. Unlike the CO2 emission, the relationship between N2O emission and precipitation was not observed because of the multiple pathways of nitrification and denitrification for N2O production induced by SOM decomposition.

学術雑誌論文

Accepted Manuscript

The definitive version is available at www.blackwellsynergy.com

0038-0768