374-4 Greenhouse Gas Flux From Fertilized Switchgrass.

Poster Number 332

See more from this Division: S06 Soil & Water Management & Conservation
See more from this Session: Bioenergy Crops and Their Impacts On Crop Production, Soil and Environmental Quality: II
Wednesday, October 19, 2011
Henry Gonzalez Convention Center, Hall C
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Marty Schmer1, Mark Liebig2, Donald Tanaka3, John Hendrickson2 and Rebecca Phillips2, (1)USDA-ARS, LIncoln, NE
(2)USDA-ARS, Mandan, ND
(3)USDA-ARS (retired), Mandan, ND

Switchgrass (Panicum virgatum L.) is being evaluated as a bioenergy crop for the United States. Field measurements of CO2, CH4, and N2O flux from switchgrass are needed to estimate the net greenhouse gas (GHG) balance of this biofeedstock. The study objective was to determine effects of N fertilization on growing-season soil-atmosphere CO2, CH4, and N2O flux from established switchgrass stands. The study was conducted in 2010 near Mandan, ND on a Parshall fine sandy loam. Static chamber methodology and gas chromatography were used to measure CO2, CH4, and N2O flux between 24 May and 14 Sep 2010 from unfertilized switchgrass and switchgrass fertilized with 67 kg N ha-1. Soil temperature and water-filled pore space (WFPS) affected growing season CO2, CH4, and N2O flux (P<0.01). Carbon dioxide flux was greatest during periods of active switchgrass growth, but differed rarely between N fertilizer treatments. In contrast, N fertilization tended to inhibit CH4 uptake when soil conditions were warm and dry, while N2O flux was consistently greater under N fertilization than without N throughout the growing season. Overall, N fertilization of switchgrass affected cumulative growing-season N2O flux (9.21.3 vs. 29.04.8 mg N2O-N ha-1 for 0 and 67 kg N ha-1, respectively; P<0.01), but not cumulative CO2 or CH4 flux (P=0.08 and 0.51, respectively). Aboveground biomass production was greater with N application (6.80.5 Mg ha-1) than without N (3.20.5 Mg ha-1) (P<0.05). Conversely, net greenhouse gas intensity (GHGI) for switchgrass production was similar between N application (2.4 Mg CO2e Mg-1) and without N (4.2 Mg CO2e Mg-1) (P=0.18). Results from this study suggest greater N2O emissions will occur when switchgrass is fertilized with N, but increased biomass production from N fertilizer results in similar GHGI.

See more from this Division: S06 Soil & Water Management & Conservation
See more from this Session: Bioenergy Crops and Their Impacts On Crop Production, Soil and Environmental Quality: II