The potential to mitigate global warming with no-tillage management is only realized when practised in the long term |
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| Authors: | Johan Six † Stephen M Ogle† F Jay breidt‡ Rich T Conant† Arvin R Mosier§ Keith Paustian†¶ |
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| Institution: | Department of Agronomy and Range Science, University of California, Davis, CA 95616, USA,;Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA,;201 Statistics, Colorado State University, Fort Collins, CO 80523, USA,;USDA/ARS, 301 South Howes, Federal Building Room 420, Fort Collins, CO 80521, USA,;Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523, USA |
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| Abstract: | No‐tillage (NT) management has been promoted as a practice capable of offsetting greenhouse gas (GHG) emissions because of its ability to sequester carbon in soils. However, true mitigation is only possible if the overall impact of NT adoption reduces the net global warming potential (GWP) determined by fluxes of the three major biogenic GHGs (i.e. CO2, N2O, and CH4). We compiled all available data of soil‐derived GHG emission comparisons between conventional tilled (CT) and NT systems for humid and dry temperate climates. Newly converted NT systems increase GWP relative to CT practices, in both humid and dry climate regimes, and longer‐term adoption (>10 years) only significantly reduces GWP in humid climates. Mean cumulative GWP over a 20‐year period is also reduced under continuous NT in dry areas, but with a high degree of uncertainty. Emissions of N2O drive much of the trend in net GWP, suggesting improved nitrogen management is essential to realize the full benefit from carbon storage in the soil for purposes of global warming mitigation. Our results indicate a strong time dependency in the GHG mitigation potential of NT agriculture, demonstrating that GHG mitigation by adoption of NT is much more variable and complex than previously considered, and policy plans to reduce global warming through this land management practice need further scrutiny to ensure success. |
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| Keywords: | global warming potential greenhouse gas mitigation nitrous oxide no-tillage |
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