Abstract
Spatial variability of soil properties in field experiments introduces an extra source of variation and inflates experimental error, thus masking true treatment effects. Data from a field experiment in which the results
were non-significant but with wide visual differences among treatments were used to study the cause of these non-significant results. Semivariograms and trend analysis were used to identify the magnitude and structure of spatial patterns in soil properties in a fertilizer field trial
conducted in Spokane County, Washington State, U.S.A. Significant quadratic trends were identified for soil properties including soil pH, acetate and bicarbonate extractable phosphorus. Coefficient of variation values were also higher for both acetate and bicarbonate extractable phosphorus. Semivariogram models for extractable P and Ca exhibited strong periodic structure while extractable K exhibited strong spherical structure These models had a range of influence from 15 to 35 m
Soil analysis of treatment plots in field experiments is needed to support the findings of the experiments and for drawing meaningful conclusions.
Aman Ullah Bhatti, David J. Mull a , F. E. Koehlar. (1995) SPATIAL VARIABILITY OF SOIL PROPERTIES IN FIELD EXPERIMENTS'AN IMPORTANT ASPECT AND A CAUSE OF VIOLATION OF ASSUMPTION OF INDEPENDENCE OF ERRORS, The Journal Soil & Environment , Volume 10, Issue (1-4).
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