Types of Soil and Soil Maps in Canada Welcome to Soils of Canada! This is the first stop for people looking for information about Canadian soils: how they form, what they look like, where different types of soil are found, and how to describe them. This website has been created by soil scientists from across Canada to give people (scientists and non-scientists) from outside the discipline of pedology information they need to understand the soils around them.

Soil formation Soil formation (also termed soil genesis or pedogenesis) is the set of dynamic processes by a soil forms, as determined by the characteristics of its environment (the soil-forming factors), over time since the deposition of the geological material upon which the soils form. Soil genesis is underlain by two major concepts.

• Soil properties result from the action and interaction of soil-forming (or pedogenic) processes.

• The type and intensity of these pedogenic processes are governed by environmental factors - the conditions of the natural world in which the soils occur and the impact of human activity on these environmental factors.

Pedogenesis leads to the development one or more distinct layers, which are formally called soil horizons. These layers may differ from each other in terms of their colour, structure, texture (the particles that compose it) or many other physical or chemical properties. A given set of horizons will result from the action and interaction of the environmental conditions, and these soil horizons will differ from place to place within a field and within a region or country. Hence the distribution of soil horizons and soil properties is not random - they are responding to a set of environmental controls.

Grassland Soils As a generalization, soils found in regions of Canada that are currently or historically dominated by grassland vegetation will fall into one of these soil Orders.

The Grassland Soils Key that follows can be used to identify the major mineral horizons present in Grassland soils. When properly described (link to CSSC online), diagnostic horizons can be used to classify a given soil profile to the Order level (see Table in Orders Overview) and provide information about which Great Group and Subgroup are appropriate, as well.

TypesofSoil:Four main soil orders are associated with forested landscapes throughout Canada: Organic, Luvisolic, Brunisolic, and Podzolic.

Organic soils occur where water accumulates to such a degree that decomposition of organic matter by microorganisms is suppressed or essentially eliminated, and layers of organic material (commonly called peat) build up over time. The remaining three orders are found in better drained forest landscapes and at the broadest level their distribution is controlled by the nature of the parent material and by climate.

Soils of the Luvisolic order are dominant in forested landscapes underlain by tills derived from underlying sedimentary rocks or on clayey lacustrine deposits (view Luvisolic map).

Because the glacial materials have a sedimentary rock origin they are relatively high in clay and in base cations such as calcium and magnesium. The diagnostic feature of Luvisolic soils is a textural contrast between the A and the B horizon – the Ae horizon has less clay than the Bt horizon. Because of the high base cation content these soils typically have neutral or alkaline pH values although some acidic Luvisols are found, especially in eastern Canada.

Soils of the Brunisolic and Podzolic orders are found in the same basic parent material type and differ primarily in terms of soil moisture available for soil-forming processes. They are both forested soils found primarily on sandy parent materials in areas underlain by igneous rocks, most prominently on the Canadian Shield, but are also found in other regions on sandy glacio-fluvial deposits. Podzolic soils are dominant on sandy deposits in ecozones or parts of ecozones where the mean annual precipitation is above about 700 mm (view Podzolic map).

At mean annual precipitation levels below this Brunisolic soils are found on the same types of sandy deposits, most notably through NW Ontario and the Canadian Shield in the Prairie provinces (view Brunisolic map).

Coniferous-dominated plant communities are the major vegetation type found on both types of soils.

Sandy glacial sediments derived from igneous rocks typically have an acidic pH because of the mineralogical composition of the sediments. The acidity of the upper soil is further increased by the organic decomposition products from the coniferous leaf litter. This creates a chemical weathering zone in the upper part of the soil where primary minerals containing aluminum, iron, and other metal ions are weathered and the ions released into the soil solution. In Podzolic soils these metal ions form complexes with the organic decomposition products (also called chelates), and the complexes move with the vertically draining water into the B horizon where they are deposited. In Brunisolic soils on sandy deposits the weathering may occur but formation of the complexes is limited and the distinctive B horizons of the Podzolic order do not form. Because of this Brunisolic soils in these setting are sometimes viewed as juvenile or immature forms of the Podzolic soils.

Further north in Canada the vegetation grades to tundra and ultimately the cold deserts of the High Arctic. In the northern third of Canada, soil-forming processes are

dominated by the presence of permanently frozen ground (permafrost) close (1 to 2 m) to the soil surface. In some cases mixing of the horizons due to ice occurs where the soil texture and moisture conditions are conducive to it. In other situations the soil horizons are not mixed together. Again in areas of water accumulation an organic layer may form at the surface of the soil (as with the Organic soils in the forested regions). These soils where permafrost is the major control on soil formation are classified into the Cryosolic Order in the Canadian System of Soil Classification.

Questions:

1. Whatarethe11typesofsoilfoundacrossCanada?(seefirstmap)2. WhatisSoilgenesis?Whatarethetwowayssoilforms?3. Whatarethe6SoilOrders?4. WhatarethefourmaintypesofSoilOrdersfoundinforestedlandscape?5. Describethepatternsandcharacteristicsofeachofthefollowingmap:Luvisolic,

Brunisolic,andPodzolic.a. Whatdoyounoticeaboutwherethevegetationislocated?Whatpercentageof

soilorderisfoundmostoftenineachmap?