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" Nitrogen and carbon in alfalfa grass/hay production in the Central High Plains: Coupling of soil-plant-atmosphere exchange "
Brekke Lane Peterson
Norton, Urszule; Krall, James M.
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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803314
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| Doc. No
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TL48098
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| Call number
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1652533543; 3673931
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| Main Entry
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Cotnoir, Amy E.
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| Title & Author
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Nitrogen and carbon in alfalfa grass/hay production in the Central High Plains: Coupling of soil-plant-atmosphere exchange\ Brekke Lane PetersonNorton, Urszule; Krall, James M.
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| College
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University of Wyoming
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| Date
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2014
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| Degree
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Ph.D.
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| field of study
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Plant Sciences
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| student score
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2014
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| Page No
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131
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| Note
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Committee members: Islam, M. Anowarul; Legg, David; Stahl, Peter D.
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| Note
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Place of publication: United States, Ann Arbor; ISBN=978-1-321-51573-2
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| Abstract
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Alfalfa (<i>Medicago sativa</i> L.)/perennial bunchgrass hay is grown on marginal soils in the Central High Plains. This region has recently been experiencing frequent droughts. Information on the effects of variation in precipitation on soil nitrogen (N) cycling, greenhouse gas (GHG) fluxes and hay productivity is limited and much needed to better understand the overall impact of the regional climate on dryland agroecosystem N and carbon (C) cycling. A 26-month experiment was conducted at the James C. Hageman Sustainable Agriculture Research and Extension Center. The site received 21% above normal (2011), 64% below normal (2012) and 30% below normal (2013) annual precipitation. Bi-weekly monitoring of GHG fluxes, soil inorganic N, dissolved organic N (DON) and soil moisture was performed in irrigated hay, dryland hay and native prairie. Results suggested that reduced precipitation increased water delivery to irrigated crops by 80%, which resulted in a decrease in cumulative nitrous oxide (N<sub>2</sub>O) fluxes from 58.2 mg season<sup>-1</sup> in 2011 to 38.1 mg season<sup>-1</sup> in 2012, CO<sub>2</sub> flux remained at 94.7 kg season<sup>-1</sup> in both years. In dryland hay, cumulative N<sub>2</sub>O declined from 88.3 mg season<sup>-1</sup> in 2011 to 34.4 mg season<sup>-1</sup> in 2012 while CO<sub>2</sub> flux remained at 48.2 kg season<sup>-1</sup> in both years. Soil labile N accumulated each year in all soils at the end of the growing season, except in dryland hay in fall 2012. Simulated precipitation experiment showed an increase in CO<sub>2</sub> from 32.5mg m<sup>-2</sup>hr<sup>-1</sup> to 42.9 mg m<sup>-2</sup>hr<sup> -1</sup> and N<sub>2</sub>O from 29.0 µg m<sup>-2</sup>hr<sup> -1</sup> to 74.3 µg m<sup>-2</sup>hr<sup>-1</sup> in dryland hay. In comparison, native prairie had an increase in CO<sub>2</sub> from 4.8 mg m<sup>-2</sup>hr<sup>-1</sup> to 36.9 mg m<sup>-2</sup>hr<sup> -1</sup> and in N<sub>2</sub>O from 6.7 µg m<sup>-2</sup>hr<sup> -1</sup> to 23.1 µg m<sup>-2</sup>hr<sup>-1</sup> in. Shoot N decreased to 3.1 g m<sup>-2</sup> in dryland hay and to 8.5 g m-2in 2012. In conclusion, drought affects more availability of soil N, soil-atmosphere N exchanges and plant biomass N than agroecosystem C. With the current predictions of increasing weather variability in this region, more effort should be placed in increasing agroecosystem efficiency to withstand increasing variability in precipitation.
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| Subject
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Agronomy; Soil sciences
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| Descriptor
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Biological sciences;Alfalfa;Carbon dioxide;Methane;Nitrous oxide;Plant biomass carbon;Plant biomass nitrogen
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| Added Entry
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Norton, Urszule; Krall, James M.
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Plant SciencesUniversity of Wyoming
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