Paper · 2004 · Agronomy Journal

Factors Underlying Yield Variability in Two California Rice Fields

Alvaro Roel; Richard E. Plant

3
claims
6
verbatim quotes
33
citations
2
research areas
—
Not open access

Abstract

Modern technologies associated with precision agriculture provide the opportunity to more precisely measure yield variability and the ecological processes underlying this variability. Effective analysis of data from these measurements requires statistical methods different from those traditionally employed on data from controlled agronomic experiments. Our objective was to develop and test multivariate statistical methods appropriate for use in analyzing precision agriculture data. We analyzed a data set taken from two commercial California rice fields and consisting of yield spatial trends together with soil core data from a grid of sample points. We used cluster analysis to discern spatiotemporal patterns in grain yield. We applied a Monte Carlo randomization process to the generation of clusters to analyze cluster stability. We then used classification and regression trees (CART) to determine the factors underlying cluster distribution. The clustering procedure successfully identified stable, physically meaningful clusters with recognizable spatial and temporal structure. Thus, the randomization procedure may present an attractive alternative to fuzzy clustering. The CART analysis identified some but not all of the factors underlying the cluster patterns. The number of available data values may have been too small to take advantage of the CART partitioning capabilities.

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Claims 3

Method / resourceobservedoriginal resultpositivemeasured

Claim · model-written summary

Clustering identified stable spatial and temporal yield clusters.

Outcome
stable, physically meaningful clusters with recognizable spatial and temporal structuree0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Oryza sativa
Oryza sativa · Taxon · picture from its Wikimedia Commons categoryDesmanthus4food · CC BY-SA 3.0 us · Wikimedia Commons ↗

Verbatim

e0

“The clustering procedure successfully identified stable, physically meaningful clusters with recognizable spatial and temporal structure”

✓ located verbatim in the source · abstract, characters 954–1090 · show in text ↑
e1

“rice fields”

✓ located verbatim in the source · abstract, characters 547–558 · show in text ↑
Method / resourceauthor interpretationoriginal resultpositivemeasured

Claim · model-written summary

Randomization may offer an alternative to fuzzy clustering.

Outcome
attractive alternative to fuzzy clusteringe0
Comparator
fuzzy clusteringe0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Oryza sativa
Oryza sativa · Taxon · picture from its Wikimedia Commons categoryDesmanthus4food · CC BY-SA 3.0 us · Wikimedia Commons ↗

Verbatim

e0

“the randomization procedure may present an attractive alternative to fuzzy clustering”

✓ located verbatim in the source · abstract, characters 1098–1183 · show in text ↑
e1

“rice fields”

✓ located verbatim in the source · abstract, characters 547–558 · show in text ↑
Method / resourceobservedoriginal resultmixedmeasured

Claim · model-written summary

CART identified some but not all factors behind cluster patterns.

Outcome
some but not all of the factors underlying the cluster patternse0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Oryza sativa
Oryza sativa · Taxon · picture from its Wikimedia Commons categoryDesmanthus4food · CC BY-SA 3.0 us · Wikimedia Commons ↗

Verbatim

e0

“The CART analysis identified some but not all of the factors underlying the cluster patterns”

✓ located verbatim in the source · abstract, characters 1185–1277 · show in text ↑
e1

“rice fields”

✓ located verbatim in the source · abstract, characters 547–558 · show in text ↑