Agronomy Journal · 2012
Corn Yields and No‐Tillage Affects Carbon Sequestration and Carbon Footprints
Clay, D. E., Chang, J., Clay, S. A., Stone, J., Gelderman, R. H., Carlson, G. C., Reitsma, K., Jones, M., Janssen, L., Schumacher, T.
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Corn Yields and No‐Tillage Affects Carbon Sequestration and …
Abstract
The corn ( Zea mays L.)–based ethanol carbon footprint is impacted by many factors including the soil's C sequestration potential. The study's objective was to determine the South Dakota corn‐based ethanol surface SOC sequestration potential and associated partial C footprint. Calculated short‐term C sequestration potentials were compared with long‐term sequestration rates calculated from 95,214 producer soil samples collected between 1985 and 2010. National Agricultural Statistics Service (NASS) grain yields, measured root/shoot ratios and harvest indexes, soil organic C (SOC) and nonharvested C (NHC) first‐order rate constants, measured SOC benchmarks [81,391 composite soil samples (0–15 cm) collected between 1985 and 1998], and 34,704 production surveys were used to calculate the short‐term sequestration potentials. The SOC short‐term, area weighted sequestration potential for the 2004 to 2007 time period was 181kg C (ha × yr) −1 . This relatively low rate was attributed to a drought that reduced the amount of NHC returned to soil. For the 2008 to 2010 time period, the area weighted short‐term sequestration rate was 341 kg (ha × yr) −1 . This rate was similar to the long‐term measured rate of 368 kg C (ha × yr) −1 . Findings from these independent SOC sequestration assessments supports the hypothesis that many of the regions surface soils are C sinks when seeded with corn. Based on short‐term C sequestration rates, corn yields, and the corn conversion rate to ethanol, the area weighted surface SOC footprints for the 2004 to 2007 and 2008 to 2010 time periods was –10.4 and –15.4 g CO 2 equ MJ −1 , respectively.
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The corn ( Zea mays L.)–based ethanol carbon footprint is impacted by many factors including the soil's C sequestration potential. The study's objective was to determine the South Dakota corn‐based ethanol surface SOC sequestration potential and associated partial C footprint. Calculated short‐term C sequestration potentials were compared with long‐term sequestration rates calculated from 95,214 producer soil samples collected between 1985 and 2010. National Agricultural Statistics Service (NASS) grain yields, measured root/shoot ratios and harvest indexes, soil organic C (SOC) and nonharvested C (NHC) first‐order rate constants, measured SOC benchmarks [81,391 composite soil samples (0–15 cm) collected between 1985 and 1998], and 34,704 production surveys were used to calculate the short‐term sequestration potentials. The SOC short‐term, area weighted sequestration potential for the 2004 to 2007 time period was 181kg C (ha × yr) −1 . This relatively low rate was attributed to a drought that reduced the amount of NHC returned to soil. For the 2008 to 2010 time period, the area weighted short‐term sequestration rate was 341 kg (ha × yr) −1 . This rate was similar to the long‐term measured rate of 368 kg C (ha × yr) −1 . Findings from these independent SOC sequestration assessments supports the hypothesis that many of the regions surface soils are C sinks when seeded with corn. Based on short‐term C sequestration rates, corn yields, and the corn conversion rate to ethanol, the area weighted surface SOC footprints for the 2004 to 2007 and 2008 to 2010 time periods was –10.4 and –15.4 g CO 2 equ MJ −1 , respectively.
The corn ( Zea mays L.)–based ethanol carbon footprint is impacted by many factors including the soil's C sequestration potential. The study's objective was to determine the South Dakota corn‐based ethanol surface SOC sequestration potential and associated partial C footprint. Calculated short‐term C sequestration potentials were compared with long‐term sequestration rates calculated from 95,214 producer soil samples collected between 1985 and 2010. National Agricultural Statistics Service (NASS) grain yields, measured root/shoot ratios and harvest indexes, soil organic C (SOC) and nonharvested C (NHC) first‐order rate constants, measured SOC benchmarks [81,391 composite soil samples (0–15 cm) collected between 1985 and 1998], and 34,704 production surveys were used to calculate the short‐term sequestration potentials. The SOC short‐term, area weighted sequestration potential for the 2004 to 2007 time period was 181kg C (ha × yr) −1 . This relatively low rate was attributed to a drought that reduced the amount of NHC returned to soil. For the 2008 to 2010 time period, the area weighted short‐term sequestration rate was 341 kg (ha × yr) −1 . This rate was similar to the long‐term measured rate of 368 kg C (ha × yr) −1 . Findings from these independent SOC sequestration assessments supports the hypothesis that many of the regions surface soils are C sinks when seeded with corn. Based on short‐term C sequestration rates, corn yields, and the corn conversion rate to ethanol, the area weighted surface SOC footprints for the 2004 to 2007 and 2008 to 2010 time periods was –10.4 and –15.4 g CO 2 equ MJ −1 , respectively.