217-15 Effects of Organic Matter Applications On Carbon Sequestration and GHG Emissions in An Upland Andisol in Japan.

Poster Number 1221

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Carbon Emissions From Agriculture

Tuesday, November 5, 2013
Tampa Convention Center, East Exhibit Hall

Ayaka W. Kishimoto1, Noriko Oura2, Sadao Eguchi3, Yasuhito Shirato3 and Seiichiro Yonemura3, (1)National Institute for Agro-Environmental Sciences NIAES, Tsukuba, Ibaraki, JAPAN
(2)National Institute for Agro-Environmental Sciences, Tsukuba, JAPAN
(3)National Institute for Agro-Environmental Sciences, Tsukuba, Japan
Soil carbon sequestration in agricultural lands has been deemed a sustainable option to mitigate rising atmospheric CO2 levels through improved management practices such as organic matter applications. Long-term organic matter applications not only increase soil organic carbon but also change organic matter quality such as increasing labile carbon proportion. This may lead to changes in nitrogen mineralization and so as the emission of N2O. Therefore, while mitigation GHG through increased sequestration of carbon in soils by organic matter applications, the trade-off with N2O emission is an issue to concern. We measured CO2 and N2O emissions from an upland Andisol managed under and long-term rice straw compost (RSC) application in central Japan. The purpose of this study was to quantify potential tradeoffs in GHGs mitigation of organic matter application while compared to the conventional fertilizer (CF) management.

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.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Carbon Emissions From Agriculture