Year of Publication: 1991
Abstract:
To provide coordinated direction for reclamation research in Alberta, the need to review the current understanding and the role of soil physical properties in soil disturbance related activities was identified. Surface coal mining, pipeline and wellhead construction, oil sands extraction, timber harvesting, and agricultural production activities alter the landscape to some degree and their cumulative effect has changed, and will continue to change, the soil resources of the province of Alberta. The nature and severity of these alterations are dependent upon inherent soil properties as affected by disturbance type and the success of reclamation and management practices. Doll (1987) believed, \"the goal of reclamation should be the establishment of a permanently stable landscape, aesthetically and environmentally compatible with the surrounding undisturbed land\". Restoration of the productivity of reconstructed soil is a complicated problem. Nielsen et al. (1983) stated \"In the past, management has been judged on annual measurements of crop productivity, and not on measurements taken below the soil surface that could be used to signal the long term consequences of management of present-day soil and water resources\". The emphasis on chemical fertility has often resulted in neglect of soil physical properties that combine with chemical properties for optimum, sustainable, soil productivity. However, it is often soil physical properties that present the main limitations to reclamation of disturbed lands (Albrecht and Thompson 1982; King and Evans 1989; McSweeney and Jansen 1984). The over-emphasis on chemical fertility is attributable, to some extent, to the lack of reliable, quantitative descriptions of soil physical properties in the field. While studying soil physical properties in the laboratory using soil cores and repacked samples has yielded much information on core and repacked samples, there are limited guarantees that such information can be applied to the landscape (White 1988). In spite of soil physical properties being recognized as one of the critical productivity limiting factors in reclamation, soil chemical properties are still often used as the only criteria of reclamation success because of difficulties in characterizing soil physical properties (Omodt et al. 1975). Often soil scientists, reclamation specialists, and agrologists concerned with management of disturbed lands are forced to seek answers to their questions regarding soil physical properties in a style once described by Oscar Wilde as \"Chaos, illumined by flashes of lightning\". Measurement of soil physical properties in the field is difficult; subject to spatial and temporal variability, time and length scales, and nonsteady, multidimensional velocity fields in a three phase system. Every soil physical property and process is also modified by weather phenomena (rainfall, frost, solar radiation, and drought), erosion, and human manipulation (management). Often the inability to characterize spatial variability prevents researchers from accurately matching soil use requirements to soil characteristics and, therefore, from predicting soil performance and behaviour. Soil physical properties and processes are closely interconnected, further complicating their measurement. It is also easy to understand why field measurement of soil physical properties has been described as a \"challenge that few have ever accepted\" (Nielsen and Biggar 1967). While that challenge is still evident in the measurement of many soil physical properties, the current challenge is related to selection of those soil physical property measurements that will best answer our questions, and the measurement techniques that will best provide that information. We must simplify a complex system by concentrating on the factors which appear to have the greatest and most direct bearing upon the problem at hand. In the view of White (1988) \"What properties we need to know and how we measure them are related directly to the questions we are attempting to answer\". Through a Soil Physical Properties Workshop held in November 1990 for people in Alberta working with soil physical properties, and an extensive literature review, the authors have attempted to identify what questions have been answered, what questions remain unanswered, and what soil physical properties and measurement techniques are best suited to meeting information needs within Alberta. The objective of this review is not to provide a methodology manual or theoretical treatise on soil physics, but rather to assess the various properties and composite parameters and processes in a manner that hopefully will clarify, not confound. The report contains a brief overview of field related measurement methodology and spatial and temporal variability for each soil physical property, followed by a review of soil physical property interrelationships, the effects of development management activities on these properties, and the prevention/amelioration/remediation/acceptance strategies employed in dealing with changes in the physical property. Recommendations for future research follow a summary of physical properties most affected by reclamation activities and differences by disturbance type.
