Gaultier, J., Farenhorst, A. and Crow, G. 2006. Spatial variability of soil properties and 2,4-D sorption in a hummocky field as affected by landscape position and soil depth. Can. J. Soil Sci. 86: 89-95. Since pesticide fate and leaching models increasingly incorporate spatial variability, the objective of this study was to quantify the variability of soil properties and 2,4-D sorption within a hummocky field as affected by landscape position and soil depth. Seventy-two soil cores collected at 5-m intervals along a transect were segmented by soil horizon (A, B and C) and landscape position (upper, mid, lower and depression). As expected, soil organic carbon content significantly decreased, and soil pH and soil carbonate content significantly increased with soil depth, while clay content was significantly greater in the B horizon than the A and C horizon. Soils from the depressional area generally had higher soil organic carbon content, soil carbonate content, clay content and soil pH than soil samples from other slope positions. The sorption of 2,4-D by soil was positively correlated with soil organic matter content and negatively correlated with soil carbonate content. These soil properties and herbicide sorption varied along the transect and with soil depth. Regardless of whether or not the landscape was segmented by landscape position, for both the A and C horizon, predictions of 2,4-D sorption by soil were generally good using simple regression models that contained soil organic carbon content and carbonate content as the only parameters. However, for the B horizon, the prediction of 2,4-D sorption by soil was very poor when all sampling points along the transect were considered, but greatly improved for the mid-and depressional slope positions when soils were segmented by landscape position. We conclude that segmentation by slope position could be a useful additional tool when predicting pesticide fate and leaching at the large-scale. As well, the negative association between soil carbonate content and 2,4-D sorption warrants further attention as a large portion of Canadian agriculture encompasses calcareous soils. . Comme il fallait s'y attendre, la teneur en carbone organique diminue significativement alors que le pH et la concentration de carbonates augmentent significativement avec la profondeur; parallèlement, il y a sensiblement plus d'argile dans l'horizon B que dans les horizons A et C. Le sol des dépressions contient généralement plus de carbone organique, de carbonates et d'argile que le sol prélevé ailleurs sur la pente et son pH est plus élevé. La sorption du 2,4-D par le sol présente une corrélation positive avec la concentration de matière organique et une autre, négative, avec la concentration de carbonates. Ces propriétés du sol et la sorption de l'herbicide varient avec l'emplacement le long du transect et la profondeur. Les modèles à régression simple n'ayant pour seuls paramètres que la concentration de carbone organique et de carbonates prévoient généralement bien la sorption du 2,4-D p...