Response of soil nitrogen retention to the interactive effects of soil texture, hydrology, and organic matter

dc.contributor.author Castellano, Michael
dc.contributor.author Lewis, David
dc.contributor.author Castellano, Michael
dc.contributor.author Kaye, Jason
dc.contributor.department Agronomy
dc.date 2018-02-18T22:19:14.000
dc.date.accessioned 2020-06-29T23:03:22Z
dc.date.available 2020-06-29T23:03:22Z
dc.date.copyright Tue Jan 01 00:00:00 UTC 2013
dc.date.issued 2013-03-21
dc.description.abstract <p>[1] Advances in nitrogen (N) saturation and retention theories have focused on soil organic matter (SOM) biogeochemistry in the absence of dynamic soil hydrology. Here we exploit two soil types with contrasting textures that span a hillslope gradient to test hypotheses that suggest N saturation symptoms are regulated by the interactive effects of soil texture, OM, and hydrology on N retention capacity (maximum pool size) and N retention kinetics (N retention rate). Down the hillslope gradient, soil solution nitrate (NO<sub>3</sub>) concentrations sampled with lysimeters increased, while <sup>15</sup>NO<sub>3</sub>-N retention decreased. Landscape location (upland, hillslope, and toeslope) and soil type interacted to affect soil solution NO<sub>3</sub> concentrations so that the downslope increase in NO<sub>3</sub> was greater in sandy versus silty soils. These patterns manifest despite a downslope increase in soil organic carbon (SOC) and C/N ratios. A positive correlation between saturated hydraulic conductivity and soil solution NO<sub>3</sub> sampled in zero-tension lysimeters during precipitation events suggested that high hydraulic conductivity promotes periodic rapid NO<sub>3</sub> transport at rates that exceed retention kinetics. The downslope increase in soil solution NO<sub>3</sub> in spite of a concomitant increase in SOC and C/N ratios provides an important contrast with previous N saturation research that highlights negative correlations between SOM C/N ratios and NO<sub>3</sub> concentrations and suggests NO<sub>3</sub> transport along connected hillslope flow paths may overwhelm stoichiometric sinks for inorganic N retention in SOM. Our results reveal important gaps in N retention theory based on SOM biogeochemistry alone and demonstrate how coupled biogeochemical and hydrological models can improve predictions of N saturation, particularly when considering periodic advective NO<sub>3</sub> transport in the vadose zone. We show that in coarse-textured soils, low capacity for protection of SOM N by association with fine mineral particles interacts with rapid hydrological flushing of NO<sub>3</sub> to enhance the expression of ecosystem N saturation symptoms.</p>
dc.description.comments <p>This is an article from Castellano, Michael J., David Bruce Lewis, and Jason P. Kaye. "Response of soil nitrogen retention to the interactive effects of soil texture, hydrology, and organic matter." Journal of Geophysical Research: Biogeosciences 118, no. 1 (2013): 280-290. doi:<a target="_blank" title="Response of soil nitrogen retention to the interactive effects of soil texture, hydrology, and organic matter"> 10.1002/jgrg.20015</a>. Posted with permission.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/agron_pubs/203/
dc.identifier.articleid 1204
dc.identifier.contextkey 10698533
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath agron_pubs/203
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/4537
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/agron_pubs/203/2013_Castellano_RepsonseSoil.pdf|||Fri Jan 14 22:23:02 UTC 2022
dc.source.uri 10.1002/jgrg.20015
dc.subject.disciplines Agriculture
dc.title Response of soil nitrogen retention to the interactive effects of soil texture, hydrology, and organic matter
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isAuthorOfPublication 1f34589d-68d7-4578-adfb-28caa0e9d604
relation.isOrgUnitOfPublication fdd5c06c-bdbe-469c-a38e-51e664fece7a
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