The smaller the scale of the map (or the more general the map), the more frequently this occurs. All soil delineations (called polygons) contain small areas of dissimilar soils that are not identified (called inclusions). Although the map may say that a discrete area of land contains a certain soil type, it must be understood that the reliability of that information is a function of the map scale. Soil survey maps are not without limitations. Why is Map Scale Important? (Soil Management Guide) What are the Limitations and Issues of a Map? How to Use a Soil Survey Report (Soil Management Guide) What are Soil Survey Reports? (Soil Management Guide) Unfortunately, reconnaissance soil survey data is not reliable enough for making on-farm management decisions. In many instances, when detailed soil survey information is not available, it is substituted with reconnaissance level information. Approximately 3/4 of the Central Region has detailed soil survey and approximately 1/3 of the Southwest Region. Essentially, there is virtually no detailed soil survey information for the Northwest region and very little for the Eastern-Interlake Region. Unfortunately, currently only about 30% of agro-Manitoba has detailed soil survey. The success of many of these activities will depend on the availability of reliable, detailed soil survey information upon which the on-farm decisions are made. In response to the public’s concern, there are many new initiatives being developed in Manitoba that use soil survey information to direct on-farm management practices. The recent intensification of agriculture, coupled with serious water quality issues throughout North America, has increased the public's concern about agriculture's management of chemicals, fertilizers and livestock manure. They are created from much more intensive site investigations ranging from 16 to 30 per section of land. Detailed soil survey maps are much more accurate and reliable for making decisions at the farm-level. Detailed soil surveys identify more of the variation in soil types across smaller landscapes. The first large-scale, or detailed, soil survey in Manitoba was published in 1972 for the Portage la Prairie area at a scale of 1:20,000. Although reconnaissance soil surveys have improved with aerial photography and interpretation since the 1940s, these maps are still based on only a small number of site investigations per section of land (approximately 6 inspections per 640 acres) and the soil map units identify only the dominant soil groups. It was at a small-scale of 1:126,000 or ½ inch to 1 mile. The first reconnaissance soil survey for Manitoba was published in 1940 for the south western area. Reconnaissance, or small-scale, soil surveys were started in 1926 in Manitoba as the first step in the development of a basic program of soil research, education, conservation and use for the province. History and Use of Soil Surveys in Manitoba Soil surveys also provide insight into the kind and intensity of land management that will be needed. As such, soil surveys can be used to plan the development of new lands or to evaluate the conversion of land to new uses. The information assembled in a soil survey can be used to predict or estimate the potentials and limitations of the soils' behaviour under different uses. Each soil type has a unique set of physical, chemical and mineralogical characteristics and has similar reactions to use and management. Soils are grouped into similar types and their boundaries are delineated on a map. Soil survey is an inventory of the properties of the soil (such as texture, internal drainage, parent material, depth to groundwater, topography, degree of erosion, stoniness, pH, and salinity) and their spatial distribution over a landscape. Soil survey information is the key to understanding the soil resource. The only way to do this is to understand the soil resource that is available. For this reason, agricultural development should only occur in areas where the soil resource will support the agricultural activity. For example, only the better agricultural soils in Manitoba will support grain and vegetable production, while more marginal agricultural soils will support forage and pasture-based production. The first step in sustainable soil management is ensuring that the soil will support the land use activity. ![]() With such a tremendously important role, it is imperative that we manage our soils for their long-term productivity, sustainability and health. In addition to supporting our agricultural needs, we rely on the soil to regulate the flow of rainwater and to act as a filter for drinking water. ![]() Together with climate, the soil determines which crops can be grown, where, and how much they will yield. We rely on it for the production of food, fibre, timber and energy crops.
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