Using electrical conductivity classification and within-field variability to design field-scale research

Cinthia K. Johnson, Kent M. Eskridge, Brian J. Wienhold, John W. Doran, Gary A. Peterson, Gerald W. Buchleiter

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Agronomic researchers are increasingly accountable for research programs and outcomes relevant to producers. Participatory research - where farmers assume leadership roles in identifying, designing, and managing on-farm field-scale research - addresses this directive. However, replication is often unfeasible at this level of scale, underscoring a need for alternative methods to estimate experimental error. We compared mean square errors to evaluate: (i) within-field variability for estimating experimental error (in lieu of replication) and (ii) classified within-field variability, using apparent electrical conductivity (ECa), for estimating plot-scale experimental error. Eight 31-ha fields, within a contiguous section of farmland (250 ha), were managed as two replicates of each phase of a no-till winter wheat (Triticum aestivum L.)-corn (Zea mays L.)-millet (Panicum miliaceum L.)-fallow rotation. The section was ECa-mapped (approximately 0- to 30-cm depth) and separated into four classes (ranges of ECa). Georeferenced sites (n = 96) were selected within classes, sampled, and assayed for multiple soil parameters (0- to 7.5- and 0- to 30-cm depths) and residue mass. Within-field variance effectively estimated experimental error variance for several evaluated parameters, supporting its potential application as a surrogate for replication. Comparison of data from the field-scale experimental site to that from a nearby plot-scale experiment revealed that ECa-classified within-field variance approximates plot-scale experimental error. We propose using this relationship for a systems approach to research wherein treatment differences and their standard errors, derived from ECa-classified field-scale experiments, are used to roughly evaluate treatments and identify research questions for further study at the plot scale.

Original languageEnglish (US)
Pages (from-to)602-613
Number of pages12
JournalAgronomy Journal
Volume95
Issue number3
DOIs
StatePublished - 2003

ASJC Scopus subject areas

  • Agronomy and Crop Science

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