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Kelly M. Livernoche
Date of Award
Master of Science (MS)
Department of Biology
L. Scott Eaton
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 carbon dioxide. The conversion of forested land to cattle pastures and their associated operational processes are noteworthy contributors to recent increases in global carbon emissions and subsequent climate change. However, appropriately managed cattle pastures have potential to be reservoirs for carbon. Rotational cattle pastures, where cattle are moved between enclosed sections of pasture, may improve soil carbon content compared to conventional practices. 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 bulk density (soil compaction) within and between a high-frequency rotational pasture (HFR), a low-frequency rotational pasture (LFR), and a conventional non-rotational (NR) pasture. 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 carbon was estimated as soil organic matter (SOM) with the loss-on-ignition technique. SOM was found to be greatest in the HFR pasture (6.61 ± 0.27%), followed by the LFR (6.00 ± 0.37%), and the NR pasture (3.47 ± 0.24%; p < 0.001). Inversely, bulk density was lowest in the HFR pasture (0.79 ± 0.01 g/cm3), followed by the LFR pasture (0.86 ± 0.04 g/cm3), and the NR pasture (0.93 ± 0.02 g/cm3; p < 0.001). Slope position had no effect on bulk density and only influenced SOM in the HFR pasture, such that SOM was greater at the top slope position (7.51 ± 0.51%) compared to the middle (6.25 ± 0.41%) and bottom (6.06 ± 0.40%) positions. Generally, SOM was greatest and bulk density lowest at 0-10 cm and SOM decreased and bulk density increased with lower soil depths. This study suggests that rotational cattle pastures could be one pathway for mitigating climate change through greater carbon sequestration and soil carbon storage.
Livernoche, Kelly M., "The effect of cattle management on soil carbon: Implications for climate change" (2017). Masters Theses. 529.