Spatial variation in soil properties is often considered significant across broad geographical regions due to soil formation factors. However, fine‐scale variations might also be significant. This study was conducted with the original intent of assessing how simple and complex mixtures of annual forages might be used to renovate perennial pastures. Private farmers in the Flatwoods, Piedmont, and Blue Ridge Major Land Resource Areas of North Carolina tested annual forages to renovate tall fescue pastures. Soil was sampled in multiple random locations in each field at depths of 0–6, 6–12, and 12–20 cm at the beginning and ending of a 3‐yr annual forage evaluation. Relative variation among five components (year of sampling n = 2, physiographic region n = 3, annual forage treatment n = 2, soil depth n = 3, and random variation from pseudoreplicates n = 3 in 2015 and n = 5 in 2018) was assessed for four soil physical, 10 soil biological, and 16 soil chemical properties. Soil chemical properties were mostly affected by physiographic region (47 ± 26% of total variation) and soil depth (33 ± 18%), soil biological properties were mostly affected by soil depth (63 ± 25%) and random pseudoreplication (14 ± 6%), and soil physical properties were equally affected by pseudoreplication (35 ± 21%), physiographic region (32 ± 18%), and soil depth (29 ± 22%). The type of annual forage had no discernible effect on soil properties, even the most biologically active. A diversity of spatial variations was important, suggesting that regional‐level ecological investigations require careful attention to an appropriate sampling design considering multiple factors. Core Ideas Soil properties were unaffected by annual forage species diversity during pasture renovation. Chemical properties varied mostly due to physiographic region (separation of ∼300 km). Biological properties varied mostly due to soil depth (separation of ∼10 cm). Physical properties varied equally among region, pseudoreplication, and depth. Net N mineralization was best predicted by a simple, rapid, and robust test of biological activity.