Introduction

Soil is inherently variable in the physical, chemical, and biological properties that determine yield potential, a fact that complicates the identification and implementation of sustainable management practices. Historically, a lack of means to delineate and address within-field heterogeneity has forced farmers to operate at the large scale, using the field as a primary management unit. Soils are sampled and inputs applied to target average requirements across fields, resulting in underperforming yields in some areas and wasted inputs in others. Increasingly, farmers seek to manage land at a smaller level of resolution (site-specific management) to improve economic and ecological outcomes.

Paradoxically, soil heterogeneity has the opposite impact on agronomic research. Scientists have traditionally relied upon small or plot-scale experiments as a means to control spatial variability and reduce experimental error. Yet, the importance of research conducted at a level of scale so divergent from that of production agriculture is sometimes questioned. Conclusions based upon data extrapolated beyond the spatial context of sampling assume the scale independence of patterns and processes (Wiens, 1989), an erroneous assumption (Cambardella et al., 1994). For this reason, growing numbers of scientists and farmers promote large-resolution (field-scale) experiments to address

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