217-15 Effects of Organic Matter Applications On Carbon Sequestration and GHG Emissions in An Upland Andisol in Japan.
Poster Number 1221
The study site is located at central Japan and the RSC field has been continually applied for rice straw compost (72.5 Mg F.W./ha, about 5.1 Mg C/ha and 275 kg N/ha) in late July since 1995. The sweet corn grew from May to July with 250 kgN/ha of chemical fertilizer addition. After RSC applying, sorghum was planted as green manure from August to November, and winter wheat was planted as green manure from November to April. All green manures and corn residue were incorporated into the soil. The GHG fluxes were measured everyday (9:00-9:30, July 2011 to July 2013) using two offline automatic gas sampling systems attached to 9 automatic chambers. Each 3 chambers used for RSC, RSC_blank (no RSC and residue incorporating) and CF treatments.
Following the RSC application and green manure incorporation, soil carbon content has increased to 5.8% which was greater than the CF management (4.2%). RSC plot showed a slight higher CO2 emission (including organic matter decomposition and root respiration) than CF plot (403.2 and 326.0 kg C m-2 period-1, respectively). Meanwhile, N2O emission from RSC plot was significantly higher than CF plot, e.g. about 2 to 3 times higher during July to October (56.1 and 23.0 mg N m-2 period-1, respectively). N2O emission from RSC seemed negligible; however, long-term RSC application could have changeg the magnitude of soil N2O emission in response to rainfall events. Significantly greater N2O emitted accompanying corn residue and green manure incorporation, and also resulted in large variation in annual N2O emission. This study highlights the importance of taking annual variability into account for quantifying organic matter managements on potential tradeoffs in soil carbon sequestration and other GHG emissions.