Soil erosion causes substantial loss of terrestrial organic carbon and nutrients in the conterminous United States

Tuesday, December 11, 2018 - 08:00
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Although the loss of organic carbon and nutrients from land to rivers by soil erosion is well documented, the spatial and temporal variability of this carbon and nutrient loss and its role in the global carbon and nutrient cycles are poorly understood. To fill this knowledge gap, we integrated a well-validated sediment yield model based on the improved Morgan model into the DOE Energy Exascale Earth System Model (E3SM) to investigate the spatial and temporal variability of terrestrial organic carbon and nutrient loss in the conterminous U.S. The modeled yield of sediment and particulate organic carbon in large river basins is consistent with previous reports. The model showed that although the carbon and nutrient loss is mainly controlled by the rate of soil erosion, the abundance of organic carbon and nutrients in soils is also an important factor. The Mississippi River Basin contributes the most organic carbon and nutrient loss by soil erosion in the conterminous U.S., with the majority of the loss occurring in its Ohio and Missouri sub-basins where the temporal variability of the loss is closely correlated with the land hydrology. The model showed that large carbon sequestration can be achieved in well-managed croplands that are under wet forest climate. In contrast, little carbon sequestration can be achieved in croplands that are under dry forest climate when compared with natural vegetations. Our simulations also showed that wildfires and landslides have important impacts on soil erosion and terrestrial carbon and nutrient pools.

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