Apparent soil electrical conductivity: Applications for designing and evaluating field-scale experiments

C. K. Johnson, K. M. Eskridge, D. L. Corwin

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


On-farm field-scale research has become increasingly common with the advent of new technologies. While promoting a realistic systems perspective, field-scale experiments do not lend themselves to the traditional design concepts of replication and blocking. Previously, a farm-scale dryland experiment in northeastern Colorado was conducted to evaluate apparent electrical conductivity (ECa) classification (within-field blocking) as a basis for estimating plot-scale experimental error. Comparison of mean-square (MS) errors for several soil properties and surface residue mass measured at this site, with those from a nearby plot-scale experiment, revealed that ECa-classified within-field variance approximates plot-scale experimental error. In the present study, we tested these findings at a second and disparate experimental site, Westlake Farms (WLF) in central California. This 32 ha site was ECa mapped and partitioned into four and five classes using a response-surface model. Classification based on ECa significantly delineated most soil properties evaluated (0-0.3 and/or 0-1.2 m) and effectively reduced MS error (P ≤ 0.10). The MS's for several soil properties evaluated at the site were then compared with those of an associated plot-scale experiment; most MS's were not significantly different between the two levels of scale (P ≤ 0.05), corroborating results from the Colorado experiment. These findings support the use of within-field EC a-classified variance as a surrogate for plot-scale experimental error and a basis for roughly evaluating treatment differences in non-replicated field-scale experiments. This alternative statistical design may promote field-scale research and encourage a reversal in research direction wherein research questions identified in field-scale studies are pursued at the plot-scale.

Original languageEnglish (US)
Pages (from-to)181-202
Number of pages22
JournalComputers and Electronics in Agriculture
Issue number1-3 SPEC. ISS.
StatePublished - Mar 2005


  • Agricultural systems
  • Classified management maps
  • Geographic information systems
  • Soil electrical conductivity
  • Statistical analyses

ASJC Scopus subject areas

  • Forestry
  • Agronomy and Crop Science
  • Computer Science Applications
  • Horticulture


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