Nitrogen sources and sinks in Iowa soils: biogeochemical links between carbon inputs, nitrate leaching, and nitrous oxide emissions

dc.contributor.advisor Michael J. Castellano
dc.contributor.author Mitchell, David
dc.contributor.department Department of Agronomy
dc.date 2018-08-11T12:57:38.000
dc.date.accessioned 2020-06-30T02:45:58Z
dc.date.available 2020-06-30T02:45:58Z
dc.date.copyright Sun Jan 01 00:00:00 UTC 2012
dc.date.embargo 2013-06-05
dc.date.issued 2012-01-01
dc.description.abstract <p>Nitrogen (N) lost from agricultural soils in the forms of nitrate (NO<sub>3</sub>) and nitrous oxide (N<sub>2</sub>O) have become major environmental concerns. Because N cycling is coupled with organic carbon (C) cycling, management practices that influence soil organic C inputs and cycling may affect reactive N losses. Management practices have been proposed to reduce N losses, including perennial vegetation buffers (PVB) and overwintering non-legume cover crops. However, the effects of these practices on N losses depend on the biogeochemical interactions between soil N and C cycling. This thesis presents investigations of the effects of these management practices on NO<sub>3</sub> and N<sub>2</sub>O losses from row crop systems in Iowa, USA. In PVBs, soil organic matter and plant biomass acted as sinks for NO<sub>3</sub> inputs. However, denitrification, stimulated by organic C inputs from perennial vegetation, appeared to be the most important NO<sub>3</sub> sink. These results indicate that integration of perennial vegetation into agricultural landscapes can return substantial amounts of N to the atmosphere and decrease watershed NO<sub>3</sub> losses in the long term. The effects of cover crops on N<sub>2</sub>O emissions were found to vary with N fertilizer rate, and cover crops increased N<sub>2</sub>O emissions at an economical N rate. These results indicate that overwintering cover crops should not be expected to consistently decrease N<sub>2</sub>O emissions from agricultural soils, even when they do decrease NO<sub>3</sub> availability for denitrification. In row crop systems with PVBs and cover crops, mineralizable C inputs to soils are a key factor influencing the biogeochemical N transformations that lead to N retention or losses. Considering the interactions between C and N cycling in agricultural soils is necessary to understand and predict the effects of management practices on environmental N losses.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/etd/12900/
dc.identifier.articleid 3907
dc.identifier.contextkey 4188225
dc.identifier.doi https://doi.org/10.31274/etd-180810-2810
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath etd/12900
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/27089
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/etd/12900/Mitchell_iastate_0097M_13127.pdf|||Fri Jan 14 19:33:07 UTC 2022
dc.subject.disciplines Ecology and Evolutionary Biology
dc.subject.disciplines Environmental Sciences
dc.subject.disciplines Soil Science
dc.subject.keywords carbon
dc.subject.keywords nitrate
dc.subject.keywords nitrogen
dc.subject.keywords nitrous oxide
dc.subject.keywords organic matter
dc.subject.keywords soil
dc.title Nitrogen sources and sinks in Iowa soils: biogeochemical links between carbon inputs, nitrate leaching, and nitrous oxide emissions
dc.type thesis en_US
dc.type.genre thesis en_US
dspace.entity.type Publication
relation.isOrgUnitOfPublication fdd5c06c-bdbe-469c-a38e-51e664fece7a
thesis.degree.discipline Ecology and Evolutionary Biology
thesis.degree.level thesis
thesis.degree.name Master of Science
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