ARS | Publication request: Soil greenhouse gas emissions affected by irrigation, tillage, crop rotation, and nitrogen fertilization

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 22, 2012
Publication Date: November 6, 2012
Citation: Sainju, U.M., Stevens, W.B., Caesar, T., Liebig, M.A. 2012. Soil greenhouse gas emissions affected by irrigation, tillage, crop rotation, and nitrogen fertilization. Journal of Environmental Quality. 41:1774-1786.

Interpretive Summary: Agricultural activities contribute about 6% of the total greenhouse gas (carbon dioxide, CO2; nitrious oxide, N2O; and methane, CH4) emissions in U.S.A. About 25% of anthropogenic emissions of CO2 and 70% of N2O originate from agriculture. Fossil fuel consumption, land conversion to cropland, lime application, and N fertilization are major sources of agriculture CO2 emissions while soil management practices contribute about 92% of the total N2O emissions. Enteric fermentation and manure management account for 96% of the total CH4 emissions from agriculture. Although emitted in small amounts, N2O and CH4 have been considered as potent greenhouse gases because of their greater global warming potential (298 and 25 times, respectively, more powerful than CO2). Little is known about the effects of irrigation and cropping systems on greenhouse gas emissions in the northern Great Plains. We evaluated the effects of irrigation, tillage, crop rotation, and N fertilization on soil temperature and water content at the 0- to 15-cm depth and CO2, N2O, and CH4 emissions in a Lihen sandy loam in western North Dakota. Treatments were two irrigation practices (irrigated and non-irrigated) and five cropping systems [conventional-tilled malt barley with N fertilizer (CTBFN), conventional-tilled malt barley with no N fertilizer (CTBON), no-tilled malt barley-pea with N fertilizer (NTB-PN), no-tilled malt barley with N fertilizer (NTBFN), and no-tilled malt barley with no N fertilizer (NTBON)]. Gas fluxes were measured on 3 to 14 d intervals using static, vented chambers from March to November, 2008 to 2011. Soil temperature was usually greater in CTBON but water content was greater in NTBFN and NTBON than in other treatments. The GHG fluxes varied with date of sampling, peaking immediately after precipitation, irrigation (>15 mm), and/or N fertilization events during increased soil temperature. Both CO2 and N2O fluxes were greater in CTBFN under irrigated condition but CH4 uptake was greater in NTB-PN under non-irrigated condition than in other treatments. While tillage and N fertilization increased CO2 and N2O fluxes by 8 to 30%, N fertilization and monocropping reduced CH4 uptake by 39 to 40%. Irrigation had minimum impact on GHG emissions compared to no irrigation. Results indicate that NTB-PN, regardless of irrigation, might mitigate greenhouse gas emissions by reducing CO2 and N2O emissions and increasing CH4 uptake relative to other treatments. To account for global warming potential for such a practice, information on productions associated with CO2 emissions along with N2O and CH4 fluxes are needed.

Technical Abstract: Little is known about the effect of management practices on soil greenhouse gas (GHG) emissions. We quantified the effects of irrigation, tillage, crop rotation, and N fertilization on soil temperature and water content at the 0- to 15-cm depth and CO2, N2O, and CH4 emissions in a Lihen sandy loam in western North Dakota. Treatments were two irrigation practices (irrigated and non-irrigated) and five cropping systems [conventional-tilled malt barley (Hordeum vulgaris L.) with N fertilizer (CTBFN), conventional-tilled malt barley with no N fertilizer (CTBON), no-tilled malt barley-pea (Pisum sativum L.) with N fertilizer (NTB-PN), no-tilled malt barley with N fertilizer (NTBFN), and no-tilled malt barley with no N fertilizer (NTBON)]. Gas fluxes were measured on 3 to 14 d intervals using static, vented chambers from March to November, 2008 to 2011. Soil temperature was usually greater in CTBON but water content was greater in NTBFN and NTBON than in other treatments. The GHG fluxes varied with date of sampling, peaking immediately after precipitation, irrigation (>15 mm), and/or N fertilization events during increased soil temperature. Both CO2 and N2O fluxes were greater in CTBFN under irrigated condition but CH4 uptake was greater in NTB-PN under non-irrigated condition than in other treatments. While tillage and N fertilization increased CO2 and N2O fluxes by 8 to 30%, N fertilization and monocropping reduced CH4 uptake by 39 to 40%. Irrigation had minimum impact on GHG emissions compared to no irrigation. Results indicate that NTB-PN, regardless of irrigation, might mitigate GHG emissions by reducing CO2 and N2O emissions and increasing CH4 uptake relative to other treatments. To account for global warming potential for such a practice, information on productions associated with CO2 emissions along with N2O and CH4 fluxes are needed.