Brown Podzolic soils are to be regarded as a transition between true Podzols and the Grey Brown Podzolic soils. They are found on the southern fringe of the Canadian Shield in Ontario and Quebec and, in the latter province, on a considerable portion of the Appalachian uplands as well. For the most part cool moist climates and forests of mixed conifers and deciduous trees are found. The Brown Podzolic soil profile is much like that of the Podzol except that it does not have a pronounced A2 leached horizon.
Such soils are not highly valued for agriculture but considerable acreages are farmed, often successfully. Some land now in farms will revert to forest but a mixed type of agriculture may be expected to maintain itself in the Eastern Townships, in the pockets of clay soils in the Nipissing lowlands, and in other such areas.
The Grey Brown Podzolic Soil Zone
This is one of the smaller soil zones of Canada, being a northern outlier of the broad belt of temperate, forested lands of northeastern United States. The northern boundary of this zone in Southern Ontario is sharply demarcated by the geological boundary of the Canadian Shield although the hardwood forests are not so confined.
As in the western plains, the parent materials are almost all glacial and derived from calcareous sedimentary rocks with an admixture of crystalline rock from the Shield. With a great wealth of land forms, drainage conditions vary and several different soil profiles will be found associated on the same parent material. In all cases with free drainage, however, the normal soil profile is that of the Grey Brown Podzolic soil. Apart from the forest litter and mould of the virgin soil, the profile is well differentiated into A 1, A 2 and B horizons. The A 1, or surface soil, is greyish brown in colour, slightly acid, and has a fair content of organic matter well incorporated in it. The A 2, or leached horizon, is usually pale brown or brownish yellow in colour and not white or very light grey as in the podzol. The B, or horizon of accumulation is brown in colour, usually sharply differentiated, containing more clay than the A horizons and having a small blocky or nut-like structure. All the lime is leached from both A and B horizons but it is nearly always found in the upper part of the parent material; there seems, however, to be little accumulation as in the case of the grassland and Grey Wooded soils. Most profiles are of only moderate depth with few much more than 36 inches.
The normal soils of this zone are of moderate fertility and under a wisely conducted mixed type of farming maintain their productivity. Some of the associated intrazonal soils are even more productive, once artificial drainage has been established. For the most part, the soils of this zone have been cleared and very little land is left in forest. In some places there are pressing problems of soil erosion and water control which are beginning to receive attention. Though not by any means the largest area of agricultural land ill Canada, it will continue to be one of the most important because of the variety of products which may be produced.
Soils of Northern Canada
The soils of the north have not yet been studied very fully but various observations have been made in the Mackenzie valley. As might be expected, the presence of permafrost in most locations inhibits the development of a mature soil profile although not always bringing about the formation of peat on the surface. On the great Pleistocene terraces, there is sufficient drainage to induce a considerable degree of podzolization.