Long-term nitrous oxide (N2O) fluxes in the upper Midwest USA: A comparison between annual and perennial systems

Ilya Gelfand, Ben-Gurion University, Midreshet Ben-Gurion, Israel, Iurii Shcherbak, Queensland University of Technology, School of Natural Resource Sciences, Brisbane, Australia, Neville Millar, Michigan State University, Hickory Corners, MI, United States, Alexandra N Kravchenko, Michigan State University, Department of Plant, Soil, and Microbial Sciences, East Lansing, MI, United States and G Philip Robertson, Michigan State University, East Lansing, MI, United States

Contact First Author: Ilya Gelfand; igelfand@bgu.ac.il

Previously Published Material: Effect of management on soil N2O emissions was reported at AGU 2013 (~15% of current presentation). The data was reanalized and updated for the current submission.

Abstract ID#: 33981

 

English Abstract:
The spatial and temporal variability of soil nitrous oxide (N2O) fluxes makes their evaluation and prediction difficult. To help address these issues we examined a long-term dataset of over 20 years of biweekly measurements of soil N2O emissions, together with measurements of multiple environmental and management parameters including soil N content and soil moisture, from eleven ecosystems: four annual cropping (corn-soybean-wheat) rotations (conventional, no-till, biological, and reduced input); perennial: alfalfa and tree plantations (coniferous and deciduous); and four successional systems: never tilled grassland, early and mid-successional, and deciduous forest.

We used these measurements to determine the effect of different agricultural and land management practices on soil N2O emissions. We found a strong (p = 0.0025) correlation between soil NO3- availability and annual cumulative N2O fluxes, and linear relationships between annual cumulative N2O emissions and soil NO3- production potential. Management and specific crop types had a strong influence on cumulative N2O emissions, with cover crops reducing emissions by ~40% during the wheat part of the rotation. Corn and soybeans crops under conventional management had lower emissions than under biological management, while wheat exhibited the opposite trend. Among the perennial ecosystems, alfalfa emitted ~six times more N2O than poplar, ~two times more than the coniferous plantation, and ~four times more than the unmanaged successional communities and the deciduous forest, which all emitted similar amounts. Daily soil N2O emissions were poorly predicted by any individual or combination of the measured variables, and had non-normal flux distributions greatly skewed toward high flux extremes.

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