Influence of increasing temperature and nitrogen input on greenhouse gas emissions from a desert steppe soil in Inner Mongolia

Abstract

We investigated the effect of increasing soil temperature and nitrogen on greenhouse gas (GHG) emissions [carbon dioxide (CO 2), methane (CH 4) and nitrous oxide (N 2O)] from a desert steppe soil in Inner Mongolia, China. Two temperature levels (heating versus no heating) and two nitrogen (N) fertilizer application levels (0 and 100 kgNha -1 year -1) were examined in a complete randomized design with six replications. The GHG surface fluxes and their concentrations in soil (0 to 50 cm) were collected bi-weekly from June 2006 to November 2007. Carbon dioxide and N 2O emissions were not affected by heating or N treatment, but compared with other seasons, CO 2 was higher in summer [average of 29.6 versus 8.6 mg carbon (C) m -2h -1 over all other seasons] and N 2O was lower in winter (average of 2.6 versus 4.0 mgNm -2h -1 over all other seasons). Desert steppe soil is a CH 4 sink with the highest rate of consumption occurring in summer. Heating decreased CH 4 consumption only in the summer. Increasing surface soil temperature by 1.3°C or applying 100 kg ha -1 year -1 N fertilizer had no effect on the overall GHG emissions. Seasonal variability in GHG emission reflected changes in temperature and soil moisture content. At an average CH 4 consumption rate of 31.65 μgCm -2h -1, the 30.73 million ha of desert steppe soil in Inner Mongolia can consume (sequestrate) about 85×10 6kg CH 4-C, an offset equivalent to 711×10 6kg CO 2-C emissions annually. Thus, desert steppe soil should be considered an important CH 4 sink and its potential in reducing GHG emission and mitigating climate change warrants further investigation. © 2011 Japanese Society of Soil Science and Plant Nutrition.