Toward Digital Soil Mapping in Canada: Existing Soil Survey Data and Related Expert Knowledge

Abstract

Digital soil mapping involves the creation of new raster-based soil attribute datasets from existing soil and environmental data, coupled with other spatial knowledge of soil distribution. The GlobalSoilMap.net project is intended to provide a digital soil map of the world on a 90 m raster base derived from existing soil data sources in each country. This paper provides an overview of the existing soil information holdings in the Canadian Soil Information System (CanSIS) in terms of their scale, coverage, and potential suitability for digital soil mapping applications. A description of a possible approach to the capture and transformation of legacy soil survey knowledge for digital soil mapping purposes is also provided. Most historical soil inventory maps and reports in Canada have been produced for the southernmost 20% of Canada’s land area by a variety of federal and provincial agencies at scales ranging from 1:20,000 to 1:250,000. Many of these datasets are available in digital format as part of the National Soil Data Base (NSDB) within CanSIS. The NSDB detailed soil map coverages provide the most precise spatial data source for building raster based digital soil mapping products, but coverage is incomplete. The Soil Landscapes of Canada (SLC) map series provides complete coverage for all of Canada, at a scale of 1:1 million. SLC maps are less spatially precise, but provide the national coverage needed for applications like the GlobalSoilMap.net project. Pedon datasets provide spatial information at specific points, but the sampling density is very low, and not well spatially distributed. Understanding the status and relevance of the NSDB data holdings, and how they can be effectively combined with expert knowledge, digital terrain models, and other data sources are important for organizing our approach to future digital soil mapping work in Canada.