Nutrient cycles across topography in drainage-impaired Corn Belt soils

dc.contributor.advisor Hall, Steven J
dc.contributor.advisor Crumpton, William
dc.contributor.advisor Lu, Chaoqun
dc.contributor.advisor McDaniel, Marshall
dc.contributor.advisor VanLoocke, Andy
dc.contributor.author Lawrence, Nathaniel
dc.contributor.department Ecology, Evolution, and Organismal Biology en_US
dc.date.accessioned 2022-11-09T02:33:06Z
dc.date.available 2022-11-09T02:33:06Z
dc.date.issued 2021-12
dc.date.updated 2022-11-09T02:33:06Z
dc.description.abstract Greenhouse gas emissions and nutrient leaching from Corn Belt soils pose a threat to both local and global human and environmental health. Topographic depressions in the US Corn Belt have documented impacts on hydrology, crop production, soil characteristics, and soil microbial communities. These topographic features also likely impact nutrient leaching rates and nitrous oxide (N2O) production. Specifically, high soil moisture in depressions may promote denitrification of nitrate (NO3-) to gaseous forms including N2O. As a result, denitrification may also effectively remove NO3- prior to leaching. In-situ measurements of N2O production and nutrient leaching rates are needed to understand both the role of topography in mediating these processes and the management strategies that could reduce them. We improved an automated soil gas chamber system capable of collecting high frequency (4-h) N2O emission measurements and collected 3 y of N2O emissions across a topographic gradient in a conventionally managed corn–soybean (Zea mays–Gycine max) Iowa agricultural field. We also collected 2 y of nutrient leaching dynamics across several topographic gradients. We found no consistent impact of topography on N2O emissions. Rather, we found that mean N2O emissions were high in both the upland and depression. A regional literature synthesis suggested that N2O emissions were similarly high across all drainage classes except for well-drained (including all drainage classes found across our field gradient). The N2O emissions from these drainage-impaired soils were twofold greater than likely soil carbon gains achievable from alternative agricultural management. We also found greater average nitrogen and phosphorus leaching rates in topographic depressions relative to uplands despite evidence for periods of greater denitrification in the depression. Nutrient leaching was especially high after fertilization, when the isotopic signature of nitrate was consistent with a combination of mineralized soil nitrogen and recent fertilizer additions. When considered with the flooding-induced crop mortality in depressions during the study period, these results indicate especially poor depression nutrient use efficiency. Management to reduce nutrient inputs or maintain consistent vegetation may reduce the environmental impact of these features.
dc.format.mimetype PDF
dc.identifier.doi https://doi.org/10.31274/td-20240329-556
dc.identifier.orcid 0000-0001-6775-514X
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/ywAbdLPv
dc.language.iso en
dc.language.rfc3066 en
dc.subject.disciplines Biogeochemistry en_US
dc.subject.disciplines Soil sciences en_US
dc.subject.disciplines Environmental science en_US
dc.subject.keywords agriculture en_US
dc.subject.keywords climate en_US
dc.subject.keywords leaching en_US
dc.subject.keywords nitrate en_US
dc.subject.keywords nitrous oxide en_US
dc.subject.keywords soil en_US
dc.title Nutrient cycles across topography in drainage-impaired Corn Belt soils
dc.type article en_US
dc.type.genre dissertation en_US
dspace.entity.type Publication
thesis.degree.discipline Biogeochemistry en_US
thesis.degree.discipline Soil sciences en_US
thesis.degree.discipline Environmental science en_US
thesis.degree.grantor Iowa State University en_US
thesis.degree.level dissertation $
thesis.degree.name Doctor of Philosophy en_US
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