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Page Index of Forest to Field Volume One
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by James A. Robertson - University of Manitoba
To date April, 1952 only Township 17 and Range 18 of the Municipality of Clanwilliam has been surveyed by the Manitoba Soils Survey. Such being the case, detailed information cannot be given, but a general description can be given, which should suit your purpose.
The parent material, that is the geological material on which these soils developed, is of two types. The predominant parent material is "boulder till" or glacial drift commonly referred to as "yellow clay." This consists of rocks and minerals which were scraped off the rock surface of the earth by glaciers as they moved south, and deposited as debris when the glaciers melted back. "Boulder till" is a mixture of stones, gravel, sand, silt and clay. The second type of parent material found is shale clay, from which extremely heavy, tough, waxy' soils are developed. This shale clay is found in the northwestern part of Township 17, Range 18. There is no sharp boundary between these two materials, and they are often found together.
The general elevation of the area ranges from 2000 to 2200 feet above sea level, with an average of 2100 feet. It has been found in Manitoba that land lying above the 1900 foot level is wooded, and this is the case in the Erickson District. The native vegetation is mixed woods, both broad-leafed and coniferous trees being found. In the sloughs and depressions, swale grasses, sedges and reeds constitute the plant life, and upon dying form a peat soil. The topography is extremely rough and irregular with moderate and steep hills, and numerous sloughs and small lakes. Such a topography causes surface run-off of water into the depressions, increasing the amount entering the soils in the lower sites, and decreasing the water entering the soils on the knolls. This variation causes locally and humid areas. The amount of water entering the soil has a decided effect on the type of soil formed. When the minerals from which soils are formed decompose, various salts are formed, some of which are more soluble than others. The rain entering the soils takes these into solution, and will remove or leach them from the soil if there is sufficient water moving downward. The rain also carries down the decomposing plant material (humus) and the very fine, invisible soil particles known as colloidal clay.
The soils of the Clanwilliam Municipality are in the transitional zone between the black soils of the prairies and the grey soils of the forest. Two zonal soils occur, "the grey wooded" soils and the "grey-black" soils. Grey wooded soils occur in relatively humid climates under wooded vegetation. On the surface there are a few inches of black soil and humus, and under this there is a
grey, ash-like layer of "horizon", which may be only slightly apparent or very prominent.
Below the grey horizon is a tough, waxy, heavy brown layer which is difficult to dig through, and which breaks into blocky or "nutty" structure when dug out. This may occur from 10" to 16"( below the surface. The grey wooded soils are found over most of the municipality, with the exception of an -area in the southwest corner of Township 17, Range 18. The impression of the grey layer is feeble in those soils developed on the shale clay parent material, and in the southern portion of the district. The grey-black soils are in the southwest part of Township 17, Range 18. These soils are originally developed under grass land vegetation as black earths with a deep black soil profile. The grass roots proliferated throughout the soil, and each year some of them died and rotted. This caused a high content of organic (plant) matter throughout the soil giving a black color. However, trees have invaded the land causing the soil climate to become more humid. The only plant material added to the soil by trees is leaves, a small percentage compared to that added by grass roots. Increased amounts of water passing through the soil have begun to carry the fine clay material and decomposing organic matter down deeper into the soil. The lower amount of organic matter and increased volume of water percolating through the soil has caused the surface soil to appear dark grey instead of black. Given a long enough time under trees it would form a grey-wooded soil.
The grey-black soils are very fertile and suited to grain farming and mixed farming. Because they are developed on boulder till, they are usually slightly to moderately stony. In texture they are relatively heavy, being called clay loams. The grey wooded soils are not usually so fertile, the plant foods having been carried out of the soil by the water passing through, but where the grey horizon is only feebly developed, the soils will grow fair crops. Those grey wooded soils developed on the shale clay are more fertile.
The chief problems of the soils are: (1) erosion: The slopes in many cases are steep and sheet erosion by water and wind has removed considerable top soil from the knolls and deposited in the lower areas. To prevent this loss continuous grain farming should not be practised. The use of rotations including grasses and legumes is necessary to keep the soils permanently productive and to reduce erosion to a minimum. (2) sloughs and depressions: In some places these occupy up to 25070 of the land. Drainage is often not feasible, with the result that much of the land is sub-marginal for agricultural use. These wet areas make cultivation more difficult, slower and more expensive. (3) low organic matter:
Organic matter acts as a reservoir of plant foods. In grey