Researcher(s)
- Franchesca Austriaco, Plant Science, University of Illinois Urbana Champaign
Faculty Mentor(s)
- Angelia Seyfferth, Department of Plant and Soil Sciences, University of Delaware
Abstract
Rice is a major crop grown throughout the world. However, it is a large contributor to the emission of methane, a potent greenhouse gas produced by microorganisms living in rice paddy soil under flooded conditions. Another issue in rice paddy soils is arsenic levels. Anaerobic or reduced conditions due to soil flooding increase reduction rates of arsenic-bearing ferric oxide minerals, resulting in the mobilization of Fe(II) and arsenic in the soil, which can be absorbed by rice plants. Recent work has suggested that biochar can be used as a redox buffer to help minimize methane emissions and arsenic availability, but this has not been tested fully in rice paddy soil. Biochar provides a way for organic matter to be recycled into the environment as a combusted, carbon-rich soil amendment. In this project, we explored the effect of biochar as a soil amendment to attenuate reducing conditions in flooded rice paddy soil to mitigate the production of methane and mobilization of arsenic.
The experiment set-up consisted of six microcosms with air-dried and sieved rice paddy soil. Three microcosms were treated with 5% biochar by weight and then flooded. Every other day, we measured greenhouse gas emissions from each microcosm. We also collected pore water samples to measure pH, oxidation-reduction potential (ORP), which we report relative to the standard hydrogen electrode (Eh), and concentrations of Mn(II) and Fe(II). We observed that biochar amendment led to less reducing conditions as evidenced by higher Eh values and lower concentrations of Mn(II) and Fe(II) than controls. This suggests that biochar has an effect of attenuating the onset of reducing conditions in rice paddy soil.