Sunday, February 19, 2017
Exhibit Hall (Hynes Convention Center)
Kelly Livernoche, James Madison University, Harrisonburg, VA
In naturally occurring ecosystems, forests function as substantial carbon sinks, storing carbon in soil and in biomass that would otherwise exist in the atmosphere as the greenhouse gas carbon dioxide. However, agricultural fields have the potential to act as reservoirs of soil carbon as well. Rotational cattle pastures, where cattle are moved between enclosed sections of pasture, may improve soil carbon content compared to conventional pastures. In rotational cattle pastures, a more even distribution of manure increases plant biomass, and increased cattle movement decreases soil compaction, thereby reducing erosion and loss of soil carbon. This study quantified differences in soil carbon and soil compaction (bulk density) within and between rotational and conventional cattle pastures. Soil samples were collected from top, middle, and bottom slope positions and were separated by soil depth (0-10, 10-20, and 20-30 cm). Bulk density was determined using dry soil weights, and soil organic carbon was analyzed by the loss-on-ignition technique. Soil carbon was greater (7.50% versus 3.26%) and bulk density was lower (0.79 g/cm3 versus 0.96 g/cm3) in rotational cattle pastures at all soil depths (p < 0.001; p < 0.001, respectively). Decreasing bulk density supports improved root growth, further increasing plant biomass, carbon sequestration, and soil carbon. Soil carbon was also affected by soil depth in rotational (p < 0.001; 0-10 cm: 9.19%, 10-20 cm: 7.40%, 20-30 cm: 5.85%) and conventional (p < .001; 0-10 cm: 5.26%, 10-20 cm: 2.83%, 20-30 cm: 1.68%) cattle pastures. However, bulk density and soil carbon did not significantly differ by slope position. This study suggests that rotational cattle pastures could be one pathway for mitigating climate change through greater carbon sequestration and soil carbon storage.