Agricultural management and greenhouse gas flux: cropland management in eastern and central US

Authors: Cavigelli, Michel; Parkin, Timothy

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 11/28/2011
Publication Date: 6/28/2012
Citation: Cavigelli, M.A., Parkin, T.B. 2012. Agricultural management and greenhouse gas flux: cropland management in eastern and central US. In: Liebig, M.A., Franzluebbers, A.J., Follett, R.F., editors. Managing Agricultural Greenhouse Gases. London, England: Academic Press. p. 177-233.

Interpretive Summary: Agricultural soils are the primary source of nitrous oxide and a minor source of methane, two important greenhouse gases that are contributing to catastrophic global climate change. Nitrous oxide emissions are expected to increase by 35-60% worldwide as pressure to increase agricultural production continues. It is imperative to identify management strategies that can reduce nitrous oxide emissions while maintaining productivity. We summarize the impacts of management on greenhouse gas emissions from cropland soils from Eastern and Central U.S. Reducing fertilizer rates to economically optimum levels could reduce soil nitrous oxide emissions by up to 50% according to recent studies. Reducing acres in high nitrogen demanding crops could provide further mitigation as nitrous oxide emissions from corn are, on average, 2.7 times as great as for soybean. Long-term (>20 years) no-till can also reduce soil N2O emissions by about 50% compared to conventional tillage. There is insufficient and/or inconsistent evidence about the impact of other proposed nitrous oxide mitigation strategies—nitrogen fertilizer and manure timing, placement or source selection; nitrification inhibitors; delayed release fertilizers; or cover crops—on emissions, or what management practices might increase methane uptake. Additional studies are needed to address these limitations. The information presented here is useful to scientists designing future studies that more fully evaluate potential mitigation strategies. In addition, this review provides crucial information to policymakers interested in designing effective greenhouse gas mitigation policies.

Technical Abstract: Agricultural soils are the primary source of nitrous oxide (N2O) and a minor source of methane (CH4), two important biogenic greenhouse gases (GHG) that are contributing to catastrophic global climate change. Nitrous oxide emissions are expected to increase by 35-60% worldwide as pressure to increase agricultural production continues so it is imperative to identify management strategies that can reduce N2O emissions while maintaining productivity. We summarize the impacts of management on GHG emissions from cropland soils from Eastern and Central U.S. Reducing fertilizer rates to economically optimum levels could reduce soil N2O emissions by up to 50% according to recent studies. Reducing acres in high N-demanding crops could provide even more N2O mitigation as N2O emissions from corn are, on average 2.7 times as great as for soybean. Long-term (>20 years) no-till can also reduce soil N2O emissions by about 50% compared to conventional tillage (CT). There is insufficient and/or inconsistent evidence indicating whether other proposed N2O mitigation strategies—N fertilizer and manure timing, placement or source selection; nitrification inhibitors; delayed release fertilizers; or cover crops—provide any mitigation, or what management practices might reduce CH4 emissions or increase CH4 uptake. Additional studies, including long-term studies incorporating sampling strategies that better capture temporal and spatial variability of GHG fluxes and factors controlling this variability, are needed to better quantify the impact of cropland management on GHG emissions.