US agriculture's relationship to soil carbon

Excerpt

Hugh Hammond Bennett is noted as having expressed after 24 years of studying soils of the United States that in his opinion soil erosion is the biggest problem confronting the farmers of the nation (Bennett and Chapline 1928). As summarized by Helms (2009), the concerns of Bennett and others eventually led to the formation of the Soil Erosion Service, which was the precursor to the Soil Conservation Service and was created within the USDA in 1935 (Bennett 1933). Here I provide a historic perspective of the use of US agricultural lands and soil carbon (C), compare amounts of soil organic carbon (SOC) in cropland versus land that has never been cultivated (native), and consider the future role of SOC in US agricultural lands. Within this context, the protection of SOC has been and will continue to be a necessary component to the economic and environmental health of US agriculture.

Little doubt can exist that among the great negative impacts related to the soil erosion observed by Bennett, if measured, would have been the severe loss of SOC associated with the eroding soil. The stable pool of SOC in soils is normally associated with the colloidal soil fraction and microaggregates and…