عنوان

Nitrogen and carbon in alfalfa grass/hay production in the Central High Plains: Coupling of soil-plant-atmosphere exchange

Number

TL48098

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

Nitrogen and carbon in alfalfa grass/hay production in the Central High Plains: Coupling of soil-plant-atmosphere exchange

General Material Designation

[Thesis]

First Statement of Responsibility

Brekke Lane Peterson

Subsequent Statement of Responsibility

Norton, Urszule; Krall, James M.

Name of Publisher, Distributor, etc.

University of Wyoming

Date of Publication, Distribution, etc.

2014

Specific Material Designation and Extent of Item

131

Text of Note

Committee members: Islam, M. Anowarul; Legg, David; Stahl, Peter D.

Text of Note

Place of publication: United States, Ann Arbor; ISBN=978-1-321-51573-2

Dissertation or thesis details and type of degree

Ph.D.

Discipline of degree

Plant Sciences

Body granting the degree

University of Wyoming

Text preceding or following the note

2014

Text of Note

Alfalfa (Medicago sativa 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 (N₂O) fluxes from 58.2 mg season^-1 in 2011 to 38.1 mg season^-1 in 2012, CO₂ flux remained at 94.7 kg season^-1 in both years. In dryland hay, cumulative N₂O declined from 88.3 mg season^-1 in 2011 to 34.4 mg season^-1 in 2012 while CO₂ flux remained at 48.2 kg season^-1 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 CO₂ from 32.5mg m^-2hr^-1 to 42.9 mg m^-2hr ^-1 and N₂O from 29.0 µg m^-2hr ^-1 to 74.3 µg m^-2hr^-1 in dryland hay. In comparison, native prairie had an increase in CO₂ from 4.8 mg m^-2hr^-1 to 36.9 mg m^-2hr ^-1 and in N₂O from 6.7 µg m^-2hr ^-1 to 23.1 µg m^-2hr^-1 in. Shoot N decreased to 3.1 g m^-2 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.

Agronomy; Soil sciences

Subject Term

Biological sciences;Alfalfa;Carbon dioxide;Methane;Nitrous oxide;Plant biomass carbon;Plant biomass nitrogen

Cotnoir, Amy E.

Norton, Urszule; Krall, James M.

Subdivision

Plant Sciences

University of Wyoming

Call Number

1652533543; 3673931

Electronic name

p

[Thesis]

276903

a

Y