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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