GUIDELINES FOR SAFE TRAFFICKING AND CULTIVATION, AND RESISTANCE-DENSITY-MOISTURE RELATIONS OF 3 DISTURBED SOILS FROM ALBERTA

The Atterberg limits and the Proctor compaction test are used by engin eers for classifying soils and for predicting stability of building fo undations. Field capacity and wilting point (agronomic limits) are use d to indicate available water for plant uptake. Few studies have relat ed the engineering criteria to the agronomic ones with regard to compa ction hazard for soils. This study investigated the relationships betw een Atterberg limits, agronomic Limits and the critical moisture conte nt (moisture content at Proctor maximum density) for three disturbed s oils (sandy loam and clay loam soils from a reclaimed Highvale mine si te, and a silt loam soil from a grazing site at Lacombe) of different textures. Relationships between bulk density, moisture content and pen etration resistance for these soils were also investigated. For the sa ndy loam and loam soils, the field capacity was close to the critical moisture content but lower than the plastic limit. Therefore, cultivat ion of these two soils at moisture contents close to field capacity sh ould be avoided since maximum densification occurs at these moisture c ontents. Overall, the critical moisture content or held capacity would be a better guide for trafficking of sandy loam and loam textured soi ls than the Atterberg limits. For the clay loam, held capacity was wit hin the plastic range. Thus trafficking this soil at field capacity wo uld cause severe compaction. In conclusion, either field capacity or p lastic limit, whichever is less, can be used as a guide to avoid traff icking at this moisture content and beyond. For the sandy loam and loa m soils penetration resistance significantly increased only with incre ased bulk density (P less than or equal to 0.05). For the clay loam so il, penetration resistance was positively related to bulk density and negatively related to moisture content. (C) 1998 Elsevier Science B.V. All rights reserved.