|Parkin, Timothy - Tim|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2009
Publication Date: 1/4/2010
Publication URL: http://jeq.scijournals.org/cgi/reprint/39/1/97
Citation: Kim, D., Isenhart, T.M., Parkin, T.B., Schultz, R.C., Loynachan, T.E. 2010. Methane Flux in Cropland and Adjacent Riparian Buffers with Different Vegetation Covers. Journal of Environmental Quality. 39:97-105. Interpretive Summary: Establishment of grass, shrub, and tree buffer zones between agricultural lands and streams has been shown to be effective in reducing nitrate pollution of surface waters. In addition to water quality benefits, buffer zones also may improve air quality by absorbing the greenhouse gas, methane, from the atmosphere. This study quantifies methane flux from buffer systems of three vegetation types and compares these fluxes with those of adjacent crop fields. It was found that methane emissions were neither increased or decreased in buffer zones. These findings should be useful to land managers and scientists interested in developing strategies to reduce greenhouse gas emissions to the atmosphere.
Technical Abstract: Conservation buffers established adjacent to cropped fields are widely promoted as off-site sinks for nonpoint source sediment and nutrients. These perennial plant systems have the potential to serve as sinks of methane (CH4) or may provide favorable conditions for CH4 production. This study quantifies CH4 flux from riparian buffer systems of three vegetation types and compares these fluxes with those of adjacent crop fields. We measured soil properties and diel and seasonal variations of CH4 flux in 7 to 17 year-old restored riparian forest buffers, warm-season and cool-season grass filters, and an adjacent crop field located in the Bear Creek watershed in central Iowa. Soil incubation experiments were conducted to quantify the production and consumption of CH4 in vitro. Forest buffer and grass filter soils had significantly lower bulk density; and higher pH, total carbon (TC), and total nitrogen (TN) than crop field soils. Soil incubation experiments indicated that CH4 consumption exceeded CH4 production in the forest buffer and grass filter soils, while crop field soils showed the opposite response. Cumulative annual CH4 flux was -0.80 kg CH4-C ha-1 y-1 in the cropped field, -0.46 kg CH4-C ha-1 y-1 within the forest buffers, and 0.04 kg CH4-C ha-1 y-1 within grass filters. There was no significant difference in net CH4 flux from soils within any vegetation type in either of the diel or seasonal CH4 measurements or incubation experiments. Results suggest that CH4 flux was not changed after establishment of perennial vegetation on cropped soils, despite significant changes in soil properties.