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Soil compaction often limits conifer regeneration on sites degraded by landings and roads, but inadequate understanding of the relationship between compaction and tree growth could lead to inappropriate soil conservation and rehabilitation efforts. We tested liquid and plastic limits, oxidizable organic matter, total carbon, particle size distribution, and iron and aluminum oxides on soil samples collected from five forest experiments in interior British Columbia. These data were used to estimate soil maximum bulk density (MBD) and relative bulk density (RBD); our objective was to relate RBD to tree growth. Height of interior Douglas-fir ( Pseudotsuga menziesii var. glauca (Bessin) Franco) was limited when RBD was >0.72. For lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) and hybrid white spruce ( Picea glauca (Moench) Voss × Picea engelmannii Parry ex Engelm.), RBDs of 0.60–0.68 corresponded to maximum height, whereas RBDs of 0.78–0.87 appeared to limit height growth. The presence of surface organic material mitigated compaction and was often associated with lower RBD. Our results illustrate the usefulness of RBD to assess compaction and suggest that soil rehabilitation should be considered on disturbed sites where soil RBD is >0.80.

Global declines in postsecondary enrollment in soil science programs over the last several decades have been mainly attributed to an overemphasis on the connection with agronomy and production agriculture but recent enrollment increases in the USA suggest change is afoot. To determine if similar trends are occurring in Canada, we inventoried undergraduate soil science course offerings at postsecondary institutions and conducted a survey to assess the status and projected trends in soil science education. We found that 64% of universities and 37% of colleges offer undergraduate soil science courses as part of degrees or diplomas in which knowledge of soil science is important (e.g., agriculture and resource management). In Canada, there are 149 undergraduate soil science courses taught in universities and 58 at colleges. On average, there are 3.2 courses taught at each university and 1.9 at each college that offer soil science courses. Soil science programs at the

As the focus of soil science education in Canada and elsewhere has shifted towards nonsoil science majors, it is important to understand if and how this has affected the scope of introductory soil science courses. The objectives of this study were to inventory Canadian postsecondary units that offer introductory soil science courses and to document attributes of instructors, students, and teaching approaches in these courses. We surveyed 58% of the instructors of introductory soil science courses across Canada, and most of these courses were offered by geography and environmental science units. The majority of instructors followed a traditional lecture (86%) and laboratory (76%) delivery format, whereas 36% used online teaching resources. Introductory courses were delivered by primarily one instructor, who held a Ph.D. in a tenure track position and in most cases developed the course themselves. Over half of the instructors surveyed used either a required or a recommended textbook, pointing to the need for creation of a Canadian-authored soil science textbook. Several follow-up studies are needed to evaluate teaching methods used in the upper level soil science courses, students' perceptions of teaching in soil science, and instructors' knowledge of resources available for online and (or) blended learning.

Biosolids application to rangelands and pastures recycles nutrients and organic matter back to soils. The effects of biosolids (20 and 60 dry Mg ha(-)(1)) and N+P fertilizer on soil aggregate stability, bulk density, aeration porosity, and total C and N of stable aggregates were evaluated 4 and 5 yr after surface application to a crested wheatgrass [Agropyron cristatum (L.) Gaertn.] pasture in the southern interior of British Columbia (BC). The experiment was established in 2001 in a randomized complete block design with four replications. The 60 Mg ha(-1) biosolids treatment (Bio 60) had a greater aggregate mean weight diameter (MWD) and proportion of water-stable soil aggregates > 1 mm relative to the control and fertilizer treatments. Temporal variation in aggregate stability was attributed to seasonal variations in soil water content. Surface application of 60 Mg ha(-1) of biosolids increased C concentrations within water-stable aggregates relative to the control from 29 to 104, 24 to 79, and 12 to 38 g kg(-1) for the 2 to 6, 1 to 2, and 0.25 to 1 mm size fractions, respectively. The concentration of N within aggregates increased in similar proportions to C. Neither soil bulk density, nor aeration porosity were affected by biosolids application. Increased aggregation and the accumulation of soil C within aggregates following biosolids application creates a potential for better soil C storage, soil water retention, nutrient availability, and ultimately the overall health of semiarid perennial pastures.