Converting conventional agriculture to poplar bioenergy crops: soil greenhouse gas flux Jessica L. Sarauer Mark D. Coleman 10.6084/m9.figshare.6959621.v1 https://tandf.figshare.com/articles/journal_contribution/Converting_conventional_agriculture_to_poplar_bioenergy_crops_soil_greenhouse_gas_flux/6959621 <p>Conversion of agricultural fields to bioenergy crops can affect greenhouse gases (GHG) such as carbon dioxide (CO<sub>2</sub>), methane (CH<sub>4</sub>), and nitrous oxide (N<sub>2</sub>O). Soil GHG emissions were measured seasonally in poplar bioenergy and agricultural fields at three Northwestern US locations. A forest stand was also used at one location for comparison. A portable gas analyzer was used to measure CO<sub>2</sub> efflux and CH<sub>4</sub> and N<sub>2</sub>O fluxes were first measured with chambers and later with gradients. Agricultural soil had 17% larger CO<sub>2</sub> efflux rates than poplar soil. Chamber fluxes showed no differences in CH<sub>4</sub> uptake but did show higher N<sub>2</sub>O fluxes in poplar than agricultural soil. Gradient CH<sub>4</sub> uptake rates were highest in agricultural soil in the summer but showed no N<sub>2</sub>O flux differences. Forest soils had smaller quarterly CO<sub>2</sub> efflux rates than agricultural soils and greater CH<sub>4</sub> uptake rates than poplar soils. The largest GHG contributor to soil GHG flux was CO<sub>2</sub>, with those being ∼1000 times larger than CH<sub>4</sub> flux rates and ∼500 times larger than N<sub>2</sub>O flux rates based on CO<sub>2</sub> equivalences. Converting conventional agricultural cropland to poplar bioenergy production does not have adverse effects on soil greenhouse gas flux and these results could be useful for modeling or life cycle analysis of land use conversion.</p> 2018-08-13 05:00:01 Biofuel soil respiration methane nitrous oxide Populus short rotation coppice