|Haile-Mariam, Shawel - WASHINGTON STATE UNIV.|
|Higgins, Stewart - WASHINGTON STATE UNIV.|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 19, 2007
Publication Date: March 1, 2008
Citation: Haile-Mariam S., H.P. Collins, and S.S. Higgins. 2008. Greenhouse Gas Fluxes from an Irrigated Sweet Corn (Zea mays L.) - Potato (Solanum tuberosum L.) Rotation. J. Environ. 37:759-771. Interpretive Summary: A two year study was conducted to investigate the effect of reduced tillage cropping systems on greenhouse gas fluxes in an irrigated potato/sweet corn crop rotation in eastern Washington. Flux measurements were made an hour after fertigation, using vented chambers, every week during the cropping season (May through August) and monthly for the rest of the year. The emission rates of N2O and CO2 were greater at the time of fertigation with no significant differences between crops or tillage practices. Approximately, 0.35% of the applied fertilizer can be lost from sandy irrigated potato fields. This low value may be due to small weekly fertilizer applications applied through the irrigation system during the growing season resulting in greater plant uptake, reducing losses due to denitrification.
Technical Abstract: There is a critical need to develop management strategies that improve soil quality through adoption of suitable crop rotations and reduced tillage for carbon sequestration and control of greenhouse gas emissions. In this study emissions of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) from agricultural soils were measured weekly during the 2005 and 2006 potato (Solanum tuberosum L.) and sweet corn (Zea mays L.) growing seasons in the irrigated semi arid region of eastern Washington. Total emissions of CO2 were 2071 and 1684 kg of CO2-C ha-1 for 2005 and 2006 study periods, respectively. Total cumulative N2O fluxes from sweet corn and potato fields were 22 and 19 times higher than the native shrub steppe site. N2O losses accounted for 0.5% (0.55 kg N ha-1) of the applied fertilizer in corn and 0.3% (0.59 kg N ha-1) of the applied fertilizer in potato during the first year of the study. Potato sites consumed more CH4 than corn and may be due to greater aeration and less compaction of potato hills. Semi-arid native shrub steppe soils in the Columbia Basin act as a year-round terrestrial sink for methane. Total gas emissions from native, corn and potato fields were 459, 7843, and 6028 kg CO2-equivalents ha-1, respectively for the 2005 growing season. Total GWP for 2006 was 14% lower than the preceding year because of lower CO2 flux from cropped fields.