Long‐term nitrous oxide fluxes in annual and perennial agricultural and unmanaged ecosystems in the upper Midwest USA
- W.K. Kellogg Biological Station Michigan State University Hickory Corners MI 49060 USA, Great Lakes Bioenergy Research Center Michigan State University East Lansing MI 48824 USA
- W.K. Kellogg Biological Station Michigan State University Hickory Corners MI 49060 USA, Department of Plant, Soil, and Microbial Sciences Michigan State University East Lansing MI 48824 USA
- Department of Plant, Soil, and Microbial Sciences Michigan State University East Lansing MI 48824 USA
- W.K. Kellogg Biological Station Michigan State University Hickory Corners MI 49060 USA, Great Lakes Bioenergy Research Center Michigan State University East Lansing MI 48824 USA, Department of Plant, Soil, and Microbial Sciences Michigan State University East Lansing MI 48824 USA
Abstract
Differences in soil nitrous oxide (N 2 O) fluxes among ecosystems are often difficult to evaluate and predict due to high spatial and temporal variabilities and few direct experimental comparisons. For 20 years, we measured N 2 O fluxes in 11 ecosystems in southwest Michigan USA : four annual grain crops (corn–soybean–wheat rotations) managed with conventional, no‐till, reduced input, or biologically based/organic inputs; three perennial crops (alfalfa, poplar, and conifers); and four unmanaged ecosystems of different successional age including mature forest. Average N 2 O emissions were higher from annual grain and N‐fixing cropping systems than from nonleguminous perennial cropping systems and were low across unmanaged ecosystems. Among annual cropping systems full‐rotation fluxes were indistinguishable from one another but rotation phase mattered. For example, those systems with cover crops and reduced fertilizer N emitted more N 2 O during the corn and soybean phases, but during the wheat phase fluxes were ~40% lower. Likewise, no‐till did not differ from conventional tillage over the entire rotation but reduced emissions ~20% in the wheat phase and increased emissions 30–80% in the corn and soybean phases. Greenhouse gas intensity for the annual crops (flux per unit yield) was lowest for soybeans produced under conventional management, while for the 11 other crop × management combinations intensities were similar to one another. Among the fertilized systems, emissions ranged from 0.30 to 1.33 kg N 2 O‐N ha −1 yr −1 and were best predicted by IPCC Tier 1 and Δ EF emission factor approaches. Annual cumulative fluxes from perennial systems were best explained by soil pools ( r 2 = 0.72) but not so for annual crops, where management differences overrode simple correlations. Daily soil N 2 O emissions were poorly predicted by any measured variables. Overall, long‐term measurements reveal lower fluxes in nonlegume perennial vegetation and, for conservatively fertilized annual crops, the overriding influence of rotation phase on annual fluxes.
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- FC02-07ER64494
- OSTI ID:
- 1290321
- Alternate ID(s):
- OSTI ID: 1427682
OSTI ID: 1290323
- Journal Information:
- Global Change Biology, Journal Name: Global Change Biology Journal Issue: 11 Vol. 22; ISSN 1354-1013
- Publisher:
- Wiley-BlackwellCopyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English