limits legume establishment and persistence on summit and toeslope positions (Guretzky et al., 2004; Harmoney Legumes establish and persist on backslope landscape positions et al., 2001). but fail on summits and toeslopes in southeastern Iowa pastures, suggesting that these pastures be managed site specifically. Visual Visual delineation of where one landscape position delineation of landscape positions, however, can be difficult, and char-ends and another begins in pastures can be difficult. acterization of spatial variability through soil sampling is expensive.Spatial information about fields or pastures are displayed, Creation of digital elevation models (DEM) and apparent soil electristored, and analyzed more effectively with a geographic cal conductivity (EC a ) mapping are inexpensive alternatives to deinformation system (GIS). A GIS allows users to create scribing field conditions. Our objective was to examine the relationa DEM for fields or pastures of interest that displays ship of DEM-derived slope, soil EC a , and legume distribution in spatial data three dimensionally and enables users to pastures. We examined these relationships across four 1.4-ha pastures.calculate topographic derivatives such as slope, aspect, Each pasture was divided into 0.46-ha plots that were assigned one flow accumulation, and wetness index (Burrough and of three stocking treatments: continuous, rotational, and nongrazed. McDonnell, 1998). Digital elevation models also allow We found that legumes, as a percentage of pasture cover, were greatest at 15 to 20% slopes and intermediate values of soil EC a . The absolute maps of plant, soil, and environmental attributes to be EC a value at which legumes were maximized varied by plot within overlayed to improve and aid visual or statistical comeach stocking system and year EC a was measured. When EC a was parisons. standardized by pasture and year, however, a nonlinear response curve Scientists have examined the relationship of DEMexplained 23 to 42% of the variation of legume cover across the plots. derived attributes such as slope, flow accumulation, and Grazing reduced competition from smooth brome (Bromus inermis wetness index with grain yields of corn (Zea mays L.) Leyss.) and reed canarygrass (Phalaris arundinacea L). These grasses and soybean [Glycine max (L.) Merr.], soil properties, dominated at 0 to 8% slopes and where EC a was either low or high and distribution of drainage classes in fields. Kravin value. We concluded that slope and soil EC a data are useful in chenko and Bullock (2000) used a DEM to examine identifying sites where legumes are successful in pastures and showed the relationship between topographic attributes such as potential for use in site-specific management of pastures. slope and flow accumulation with soil properties and corn and soybean grain yield. Moore et al. (1993) used a DEM to examine the relationship between topographic