Assessing the state of agricultural resources: Improving the land resource data base

Cressman, D.
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Agriculture Canada

The general goal of this project was to develop and apply methodologies in Wilmot Township and the Town of Whitchurch-Stouffville for upgrading and interpreting soil survey information. These upgrades improve our ability to assess the condition of the agricultural land base and make the information more useful for resource management and land use planning purposes. For Wilmot Township a technique was developed for producing an intermediate scale (1:50,000) soil association map which can be used to assess the state of agricultural resources across the Township. The same technique can easily be applied to the Region of Waterloo as a whole. The objective was to convert a very detailed soil map on an uncontrolled photomosaic base (1:20 000 scale) to a scale and level of detail that is more commonly used in land use and resource management planning (1:50000) and to register the new soil map to the Ontario Base Mapping (OBM) in a GIS environment. The initial work in Wilmot focused on the development of an appropriate methodology for generalizing the soil map units (polygons). Three study areas representing the principal landforms and soil types in the Township were chosen for test applications of three generalization techniques. A preferred method was selected from the three techniques based on the degree of clarity, accuracy, information content and time required to produce the required product. New soil polygons were complied in a digital format to provide a working base for assessing the state of agricultural resources. A data base structure for the polygon attribute data in the GIS was also developed. Once the generalized soil map was completed, a variety of soil survey interpretations were prepared and the soil data were used in a pilot application in the Bamberg Creek watershed to assess the state of agricultural land resources. A soil capability map was produced at a scale of 1:50 000 for the Township using modified Canada Land Inventory (CLI) ratings from the Soils of Waterloo County. Capability ratings for small grains and oil seeds were also determined for comparison purposes using the criteria of 'Land Suitability Rating System for Spring Seeded Small Grains', Working Document from the Research Branch of Agriculture Canada, 1992). For the work in the Town of Whitchurch-Stouffville, OBM data in digital form were obtained and incorporated into a GIS data base. These data were then interpreted in a Digital Terrain Model (DTM) to produce a slope map for the Town. The slope map units were checked in the field and then merged with soil map units on the County of Simcoe. The soil map were then also digitized into the GIS data base. For each polygon a CLI capability rating and a rating for oil seeds and small grains was established. From these interpretations a 1:50 000 CLI soil capability map was produced. A search was undertaken for other digital data covering the study area. The only data discovered include digital maps of natural heritage areas compiled by the Oak Ridges Moraine (ORM) Office of the Ontario Ministry of Natural Resources (OMNR) and digital agricultural land use systems maps compiled by the Ontario Ministry of Agriculture and Food (OMAF). To support an assessment of the state of agricultural land resources in the Town, it was necessary to obtain and digitize information from the ORM Office of OMNR on proposed land uses. These data covered the Oak Ridges portion of the Town. An overlay analysis was then performed in the GIS data base to determine the capability classes of land proposed to be converted to non-agricultural use on the Oak Ridges Moraine portion of the Town.

Green Plan
soil, soil survey, soil map, land use planning, soil resource data base, soil association map, agricultural resources, soil landscape polygons