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Submitted to: American Geophysical Union
Publication Type: Book / Chapter Publication Acceptance Date: 1/17/2017 Publication Date: 11/10/2017 Citation: Schmer, M.R., Stewart, C.E., Jin, V.L. 2017. Empirical evidence of soil carbon changes in bioenergy cropping systems. In: Qin, Z., Mishra, U., and Hastings, A., editors. Bioenergy and Land Use Change. First Edition. Hoboken, NJ: John Wiley & Sons, Inc. p.99-114 Interpretive Summary: Biofuels are seen as a potential solution to diversify rural economies. Accurate carbon accounting is necessary to measure the overall carbon intensity of new biofuel feedstocks. Changes in direct soil organic carbon (SOC) can have a major impact on estimating carbon intensities from biofuels. Even though SOC represents a small portion of a soil’s mass, it plays an essential role in soil functioning and carbon cycling. Conversion of native ecosystems to annual bioenergy crops will likely result in significant SOC stock loss. The expected use of agricultural residues for bioenergy and its effect on SOC use will largely be dependent on residue removal amounts, climate, management practices, previous land history, topography, and soil type. Perennial bioenergy crops have the ability to significantly increase SOC stocks while providing substantial biomass quantities on degraded cropland or idle land under proper management. A multi-feedstock landscape approach minimizes economic risks in meeting feedstock demands for bioenergy production by providing sufficient feedstock production while maintaining or increasing SOC. Technical Abstract: Biofuels are seen as a near-term solution to reduce greenhouse gas (GHG) emissions, reduce petroleum usage, and diversify rural economies. Accurate accounting of all GHG emissions is necessary to measure the overall carbon (C) intensity of new biofuel feedstocks. Changes in direct soil organic carbon (SOC) can have a major impact on estimating overall GHG emissions from biofuels. Even though SOC represents a small portion of a soil’s mass, it plays an essential role in soil functioning and C cycling. Currently, there are limited long-term datasets that can be used to evaluate SOC changes of perennial energy crops. However, certain recommendations can be made. Conversion of native ecosystems to annual bioenergy crops will likely result in significant SOC stock loss. The expected use of agricultural residues for bioenergy and its effect on SOC use will largely be dependent on residue removal amounts, climate, management practices, previous land history, topography, and soil type. Perennial bioenergy crops have the ability to significantly increase SOC stocks while providing substantial biomass quantities on degraded cropland or idle land under proper management. A multi-feedstock landscape approach minimizes environmental risks in meeting feedstock demands for bioenergy production by providing sufficient feedstock production while maintaining or increasing SOC. |
