Soil management zones delineated by electrical conductivity to characterize spatial and temporal variations in potato yield and in soil properties

Within-field management zones (MZ) delineated using soil electrical conductivity (EC) may provide the basis for site-specific crop management (SSCM). The objective of this study was to evaluate the efficiency of EC for delineating homogenous soil MZ related to soil properties. Soil EC was measured on a 15-m x 15-m grid using a Geonics EM38 on a 13.8-ha commercial field under potato (Solanum tuberosum L.) production. A subset of this grid (30 in x 30 in) was used to collect soil samples (0-0.2 in) and to perform soil profile descriptions (1.2 in). Soil samples were analyzed for physicochemical properties (texture, organic matter, pH, Mehlich-3 extractable elements). Potato tuber yields were measured using a yield monitor in 1998, 1999, and 2000. The K-means clustering algorithm was performed for delineating MZ using the soil EC kriged data matrix. Two MZ were found to be optimal for implementing SSCM management for potato in this field. These two MZ showed significant differences in soil water regime (thickness of sandy deposit over the clayey substratum, water table depth, water-holding capacity) and in some soil physico-chemical properties (soil organic matter, soil P, soil pH). Significant differences in potato yields (5.9 t ha(-1)) between the two MZ were attributed to differing water supply. Soil EC has the potential to be used efficiently for delineating within-field MZ for soils in which soil deposits and soil physical properties control soil moisture availability.