Sources of variability in nitrogen availability in Iowa cornfields

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dc.contributor.advisor Alfred M. Blackmer
dc.contributor.author Perdomo, Carlos
dc.contributor.department Agronomy
dc.date 2018-08-23T02:42:40.000
dc.date.accessioned 2020-06-30T07:06:59Z
dc.date.available 2020-06-30T07:06:59Z
dc.date.copyright Sun Jan 01 00:00:00 UTC 1995
dc.date.issued 1995
dc.description.abstract <p>Studies were conducted to learn more about the spatial structure of soil NO[subscript]3[superscript]- concentrations in cornfields in late spring and to identify some major causes of variability in these concentrations. This information is specifically needed to aid in design of efficient sampling strategies for the late-spring test for nitrogen (N) availability, which is a new management tool that enables site-specific evaluation and adjustment of fertilization practices. One study assessed the importance of windrows of plant residue left by combines as a source of variability in soil nitrate (NO[subscript]3[superscript]-) concentrations for the next crop. Observations made in several fields having distinct windrows showed that yields of corn were significantly affected, but the effects on soil NO[subscript]3[superscript]- concentrations were minor compared to other unidentified sources of variability. A second study evaluated rows of young corn plants as a potential source ofvariability. Results from several fields revealed cyclic patterns in soil NO[subscript]3[superscript]- concentrations along transects perpendicular to rows. A third study evaluated nonuniform distributions of fertilizers across the width of large applicators as a possible source of variability. Observations made in several fields revealed cyclic patterns in NO[subscript]3[superscript]- concentration that seemed to be caused by fertilizer applicators and other farming operations. Models were developed that enabled integration of the observed cyclic patterns into geostatistical models commonly used to describe spatial structure. Procedures were developed for partitioning variability caused by two or more superimposed cycles;Overall, the results show that cyclic patterns are an important component of the spatial structure of soil NO[subscript]3[superscript]- concentrations in cornfields. Consideration of these cyclic patterns should enable more complete characterization of the spatial structure of soil NO[subscript]3[superscript]- concentrations in fields and, therefore, enable design of more efficient sampling strategies to assess NO[subscript]3[superscript]- concentrations within these fields. In addition, the ability to detect previously unrecognized cyclic patterns in soil NO[subscript]3[superscript]- concentrations gives the ability to demonstrate the benefits of using practices that minimize formation of troublesome cyclic patterns in fields.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/rtd/10710/
dc.identifier.articleid 11709
dc.identifier.contextkey 6415871
dc.identifier.doi https://doi.org/10.31274/rtd-180813-11693
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/10710
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/63887
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/rtd/10710/r_9531776.pdf|||Fri Jan 14 18:26:52 UTC 2022
dc.subject.disciplines Agricultural Science
dc.subject.disciplines Agriculture
dc.subject.disciplines Agronomy and Crop Sciences
dc.subject.keywords Agronomy
dc.subject.keywords Soil science (Soil fertility)
dc.subject.keywords Soil fertility
dc.title Sources of variability in nitrogen availability in Iowa cornfields
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication fdd5c06c-bdbe-469c-a38e-51e664fece7a
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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