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Field-to-farm gate greenhouse gas emissions from corn stover production in the Midwestern U.S.

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Title: Field-to-farm gate greenhouse gas emissions from corn stover production in the Midwestern U.S.
Authors: Locker, C. Rebecca1 (AUTHOR), Torkamani, Sarah1 (AUTHOR), Laurenzi, Ian J.1 (AUTHOR) ian.j.laurenzi@exxonmobil.com, Jin, Virginia L.2 (AUTHOR), Schmer, Marty R.2 (AUTHOR), Karlen, Douglas L.3 (AUTHOR)
Source: Journal of Cleaner Production. Jul2019, Vol. 226, p1116-1127. 12p.
Subjects: Corn stover, Greenhouse gases, Carbon content of plants, Farm management, Corn, Accounting methods
Abstract: Measured field data were used to compare two allocation methods on life cycle greenhouse gas emissions from corn (Zea mays L.) stover production in the Midwest U.S. We used publicly-available crop yield, nitrogen fertilizer, and direct soil nitrous oxide emissions data from the USDA-ARS Resilient Economic Agricultural Practices research program. Field data were aggregated from 9 locations across 26 site-years for 3 stover harvest rates (no removal; moderate removal – 3.1 Mg ha−1; high removal – 7.2 Mg ha−1) and 2 tillage practices (conventional; reduced/no-till). Net carbon uptake by crops was computed from measured plant carbon content. Monte Carlo simulations sampled input distributions to assess variability in farm-to-gate GHG emissions. The base analysis assumed no change in soil organic carbon stocks. In all cases, net CO 2 uptake during crop growth and soil-respired CO 2 dominated system emissions. Emissions were most sensitive to co-product accounting method, with system expansion emissions ∼15% lower than mass allocation. Regardless of accounting method, lowest emissions occurred for a moderate removal rate under reduced/no-till management. The absence of correlations between N fertilization rate and stover removal rate or soil N 2 O emissions in this study challenges the use of such assumptions typically employed in life cycle assessments Storage of all carbon retained on the field as SOC could reduce emissions by an additional 15%. Our results highlight how variability in GHG emissions due to location and weather can overshadow the impact of farm management practices on field-to-farm gate emissions. Image 1 • Two life cycle assessment approaches using field-based data were compared for corn (Zea mays L.) stover-based biofuel. • Greenhouse gas emissions were most sensitive to co-product accounting method. • Emissions were 15% lower using the system expansion method vs. mass allocation. • Site-specific variability in soil emissions and crop yield affected field-to-farm gate emissions. • Regardless of accounting method, lowest emissions occurred with moderate stover removal under reduced/no-till management. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Measured field data were used to compare two allocation methods on life cycle greenhouse gas emissions from corn (Zea mays L.) stover production in the Midwest U.S. We used publicly-available crop yield, nitrogen fertilizer, and direct soil nitrous oxide emissions data from the USDA-ARS Resilient Economic Agricultural Practices research program. Field data were aggregated from 9 locations across 26 site-years for 3 stover harvest rates (no removal; moderate removal – 3.1 Mg ha−1; high removal – 7.2 Mg ha−1) and 2 tillage practices (conventional; reduced/no-till). Net carbon uptake by crops was computed from measured plant carbon content. Monte Carlo simulations sampled input distributions to assess variability in farm-to-gate GHG emissions. The base analysis assumed no change in soil organic carbon stocks. In all cases, net CO 2 uptake during crop growth and soil-respired CO 2 dominated system emissions. Emissions were most sensitive to co-product accounting method, with system expansion emissions ∼15% lower than mass allocation. Regardless of accounting method, lowest emissions occurred for a moderate removal rate under reduced/no-till management. The absence of correlations between N fertilization rate and stover removal rate or soil N 2 O emissions in this study challenges the use of such assumptions typically employed in life cycle assessments Storage of all carbon retained on the field as SOC could reduce emissions by an additional 15%. Our results highlight how variability in GHG emissions due to location and weather can overshadow the impact of farm management practices on field-to-farm gate emissions. Image 1 • Two life cycle assessment approaches using field-based data were compared for corn (Zea mays L.) stover-based biofuel. • Greenhouse gas emissions were most sensitive to co-product accounting method. • Emissions were 15% lower using the system expansion method vs. mass allocation. • Site-specific variability in soil emissions and crop yield affected field-to-farm gate emissions. • Regardless of accounting method, lowest emissions occurred with moderate stover removal under reduced/no-till management. [ABSTRACT FROM AUTHOR]
ISSN:09596526
DOI:10.1016/j.jclepro.2019.03.154