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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #313629
Title: Review of soil organic carbon measurement protocols: A US and Brazil comparison and recommendation

Author
item DAVIS, MAGGIE - Oak Ridge National Laboratory
item ALVES, BRUNO - Embrapa
item Karlen, Douglas
item KLINE, KEITH - Oak Ridge National Laboratory
item GALDOS, MARCELO - Brazilian Bioethanol Science & Technology Laboratory
item ABULEBDEH, DANA - University Of North Carolina

Submitted to: Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2017
Publication Date: 12/26/2017
Citation: Davis, M.R., Alves, B.J.R., Karlen, D.L., Kline, K.L., Galdos, M., Abulebdeh, D. 2017. Review of soil organic carbon measurement protocols: A US and Brazil comparison and recommendation. Sustainability. 10(1):53. http://doi.org/10.3390/su10010053.

Interpretive Summary: Soil profiles are an important sink for carbon (C) because they contain approximately three times more C than the atmosphere and three to four times more C than vegetation. Quantifying the amount of C in soil profiles and changes in response to agricultural management practices is difficult because of the wide array of sampling strategies. This literature review examines different sampling strategies being used to quantify soil C in Brazil and the USA where sugarcane or corn are being harvested as feedstock for bioenergy production. The authors also supply specific soil sampling protocols to help standardize future SOC assessments. This information will be useful for scientists, conservationists, soil management consultants, producers, and those investing in bioenergy feedstock production, as well as those who desire to reduce atmospheric CO2 concentrations by increasing C sequestration.

Technical Abstract: The global soil carbon pool represents three to four times the amount of carbon stored in the atmosphere and in living biomass. Accurate measurements of changes in soil carbon are important to understand the impacts of current land management and to identify opportunities to enhance carbon sequestration and retention in soils. Most research has focused on measuring changes in soil organic carbon (SOC) because it impacts productivity necessary to help meet demand for food, feed, fiber, energy, and other renewable biomaterials. Land management to conserve and increase SOC is often identified as a cost-effective climate change mitigation and adaptation strategy. SOC change impacts lifecycle assessment calculations for globally traded bio-based products. Broad agreement on the importance of SOC contrasts with uncertainties associated with SOC changes under different contexts. This paper reviews SOC studies with a focus on the two primary feedstock crops for current global ethanol production, corn (Zea mays L.) in the U.S. and sugarcane (Saccharum officinarum L.) in Brazil. We compared sampling protocols for measuring SOC and found a lack of consensus on sampling strategies, measurement techniques, and verification methods that could influence reported SOC values. Different sampling designs (i.e., a random sampling used in the US and a systematic design used in Brazil), sample collection methods (i.e., the use of excavated pits and augers in Brazil, and cores in the US), sampling depths, and analysis procedures (e.g., defined depth increments) contribute to variability in reported values. The authors conclude with research recommendations and propose an approach for more consistent and comparable measurements of SOC change.