Effects of Biochar Use On Greenhouse Gas Emissions From Organic Farming In the Ohio Valley.

Greenhouse gases emitted through human activities contribute significantly to climate change. Globally, agriculture is the second largest source of carbon dioxide (CO₂) after fossil fuel combustion, and is a dominant source of methane (CH₄) and nitrous oxide (N₂O). In addition to releasing greenhouse gases, most agricultural practices deplete the organic carbon in soils, negatively impacting fertility and moisture retention. Furthermore, most agricultural production relies on energy-intensive synthetic fertilizers, which then result in nutrient runoff and aquatic system eutrophication.

In order to examine the environmental impacts of a switch to local, organic vegetables for food supplies, this farm-based project examined the impact of organic fertilizers on soil greenhouse gas emissions, as well as the potential greenhouse-gas-mitigating effects of biochar. Biochar is a type of processed charcoal that has shown potential both as a carbon-sequestration pathway, and as a natural fertilizer. We applied varying amounts of biochar to a 1750-square-foot patch of garden in northern Cincinnati. Using a three-chamber system, we measured the amount of greenhouse gases emitted or sequestered by the control and experimental (biochar amended) soil patches using a Shimadzu GC-2014 gas chromatograph that measured CO₂, N₂O, and CH₄. We hypothesized that the biochar would decrease N₂O and CH₄ emissions relative to the non-biochar plot.

Our research team has collected more than a year's worth of data, with initial results showing that the N₂O emissions are similar to conventional agriculture, despite the use of organic fertilizers.  We have also shown that our plot has a reduced ability to consume atmospheric methane as compared to conventional agriculture. Biochar incorporation did not seem to mitigate the release of N₂O and CH₄, but future work will examine potential impacts of greater biochar incorporation on soil greenhouse gas dynamics.