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Covariance Structures in Conventional and Organic Cropping Systems
Author
Source
International Journal of Agronomy
Issue
Vol. 2013, Issue 2013 (31 Dec. 2013), pp.1-8, 8 p.
Publisher
Hindawi Publishing Corporation
Publication Date
2013-12-31
Country of Publication
Egypt
No. of Pages
8
Main Subjects
Abstract EN
Guidelines are needed to develop proper statistical analyses procedures and select appropriate models of covariance structures in response to expected temporal variation in long-term experiments.
Cumulative yield, its temporal variance, and coefficient of variation were used in estimating and describing covariance structures in conventional and organic cropping systems of a long-term field experiment in a randomized complete block design.
An 8-year database on 16 treatments (conventional and organic cropping systems, crop rotations, and tillage) was subjected to geostatistical, covariance structure, variance components, and repeated measures multivariate analyses using six covariance models under restricted maximum likelihood.
Differential buildup of the cumulative effects due to crop rotations being repeated over time was demonstrated by decreasing structured and unstructured variances and increasing range estimates in the geostatistical analyses.
The magnitude and direction of relationships between cumulative yield and its temporal variance, and coefficient of variation shaped the covariance structures of both cropping systems, crop rotations, and phases within crop rotations and resulted in significant deviations of organic management practices from their conventional counterparts.
The unstructured covariance model was the best to fit most factor-variable combinations; it was the most flexible, but most costly in terms of computation time and number of estimated parameters.
American Psychological Association (APA)
Jaradat, Abdullah A.. 2013. Covariance Structures in Conventional and Organic Cropping Systems. International Journal of Agronomy،Vol. 2013, no. 2013, pp.1-8.
https://search.emarefa.net/detail/BIM-476121
Modern Language Association (MLA)
Jaradat, Abdullah A.. Covariance Structures in Conventional and Organic Cropping Systems. International Journal of Agronomy No. 2013 (2013), pp.1-8.
https://search.emarefa.net/detail/BIM-476121
American Medical Association (AMA)
Jaradat, Abdullah A.. Covariance Structures in Conventional and Organic Cropping Systems. International Journal of Agronomy. 2013. Vol. 2013, no. 2013, pp.1-8.
https://search.emarefa.net/detail/BIM-476121
Data Type
Journal Articles
Language
English
Notes
Includes bibliographical references
Record ID
BIM-476121