[UPDATED: Oct. 30, 2020] Naming (classifying) soils is not the same as naming plants or animals. Plant classification can be a purely scientific endeavour and they name a plant by genus (Triticum = wheat) and species (Triticum aestivum = bread wheat).
Classifying soils is a complex affair not always understood. In this short piece, we will peel away the fancy stuff and boil it down to what we can use at the farmgate.
Why bother classifying soils?
We need to classify, or name, soils so we have a framework to work with when we manage different soils for various agricultural pursuits. All research work should include the soil names being studied — or the information cannot be applied to the field in any meaningful way.
To achieve this goal, we must also make maps that show where the various soils can be found. With a soil map in hand (or online) we can be more specific with recommendations for cropping practices.
We will make specific reference to our three Prairie provinces and the different ways they have named and mapped soils. Despite the fact that the Feds were always very involved in soil classification and mapping, our three provinces still went their separate ways when it came to mapping. I doubt many readers are surprised by that fact. As Prairie folk we “do it our way.”
Science and fundamental symbols
The symbol of chemistry is the periodic table and for geology it is the clock, or the geologic time scale.
For soil science, the soil profile is the starting point of soil classification.
Scientific soil classification is a complicated business and various systems are used in different parts of the world. The Canadian system has some recognizable names like black chernozem = grassland soil = Blaine Lake loam as an example (Figure 1 below), but also such titillating names as degraded eutric brunisol.
The American system abandoned all common names and made up a whole new language. We see such names as argioquic argiolboll.
Do not get me wrong — the scientific system plays an important role, but if overemphasized it can end up with soil scientists talking only to one another. The big thing is to boil it down to something useful at the farmgate.
The soil (climatic) zone is the starting point of practical soil mapping on the Prairies. The soil zones are brown, dark-brown, black, thick black, grey-black and grey. The soil zones are broad zones that represent the climate and, hence, the organic matter of soils. Organic matter increases from soil zones brown to thick black and decrease in the grey-black and grey zones.
The only three-province map I know of that separates all of those zones is the foldout cover of Henry’s Handbook of Soil and Water.
Please note, there is some confusion surrounding the word “zone” when referring to that term with respect to soil classification or precision agriculture. With the development of variable-rate techniques, etc., the word zone is also used to describe the different management areas within a field. In hindsight, area would have been a better word than zone.
Individual soil profiles can vary greatly over a quarter section in a repetitive manner determined by topography and resulting water flow over or through the soil. Soil geographic names can be applied to each individual profile (soil series) or to the repetitive group of soil profiles (soil association).
Figure 2 (at top) shows how it works. If the field was mapped as a soil association it would be called Weyburn loam. The report would explain the various individual soil profiles in that association. If it was mapped as a soil series, each soil would be named, for example, soil X, soil Y, and soil Z.
The definition of soil association is a group of closely associated soil profiles on one parent material and one soil zone. A place name is assigned to each soil association. That place name is usually the name of a town near where the soil was first recognized and described by soil surveyors.
The definition of soil series is an individual soil profile on one parent material and one soil zone. A place name is assigned to each soil series. That place name is usually the name of a town near where the soil was first recognized and described by soil surveyors.
In mapping soils, the basic unit can be the soil association or the soil series. The town name assigned to the association or series is the name that is used and should become in common use by all.
How that is applied in various provinces is described next.
In practical agriculture, Saskatchewan soils are mapped as soil associations and texture with names like Regina heavy clay (HvC) or Weyburn loam (L). Regina is the soil association which refers to the parent material (glacial lake clay) and the soil climatic zone (dark-brown). Weyburn soils are developed on material the glaciers dropped or plastered on the landscape (i.e. glacial till) and also in the dark-brown soil climatic zone.
When the first soil survey was completed in the 1940s, Saskatchewan combined and simplified all previous surveys into one comprehensive system of soil names (associations) and published it as Soil Survey Report No. 12 (up to Township 48) and Soil Survey Report No. 13 (agriculture areas north of Township 48).
Those reports and maps were the basis of all agronomic work for most of my time at the University of Saskatchewan. Everyone was singing from the same songbook and it worked very well.
The second Saskatchewan soil survey carried on from the 1950s to the early 1990s. Over time, concepts and details changed, but no unified system of soil paper maps was published.
Saskatchewan Soil Information System (SKSIS)
In recent years, Angela Bedard-Haughn at the U of S has spearheaded the production of a seamless online system of access to soil survey information (visit sksis.ca). What makes it shine is the air photo that lies just beneath the soil map to be viewed at the same time.
The digital presentation is easy to use. If I can do it, anyone can. In my opinion, more simplification of soils information is needed to make it useful to more agronomists.
I use SKSIS almost every day. When I see a “land for sale or rent” ad, it is a quick study with SKSIS to see what it is like.
Soil maps in Alberta are fundamentally different in that they name soils at the series level rather than the association. There is a reason for that. Alberta has much less depth of glacial deposits and very little pothole country, which prevents water drainage from the field. Consequently, Alberta does not have as many of the complex individual soil profiles that we do in Saskatchewan.
Alberta never did combine the early soil survey reports into a unified system of paper maps. However, in recent years, the information has been combined in a digital format which is available online at soil.agric.gov.ab.ca/agrasidviewer.
I find the online access hard to navigate, but the deficiency is likely this digitally challenged old fossil. I do not use it often enough to really learn the system. With more practice, it would likely become easier.
Manitoba has a much smaller land base than the other two provinces. The original concept of mapping soil associations came from Joe Ellis of the University of Manitoba. His 1943 Report of Reconnaissance Soil Survey of South Central Manitoba is a classic and still a very useful document. It covers the farm my dad was raised on near Stockton, so I have had a chance to check it out first-hand in the field. And it passed the test!
The Soils of Manitoba by Joseph Henry Ellis, published in 1938, is also a classic and is still available for purchase online.
There are many good soil maps in Manitoba. In some areas, there are very detailed soil surveys where they actually walked fields in transects to get a detailed map. There are 76 detailed maps of areas including rural municipalities and even some townsites and parks. The detailed surveys mostly map soils at the series level.
Manitoba has never put together a comprehensive map of the province and there is no online access as in Saskatchewan (see correction at bottom). However, all of the Manitoba paper maps and reports are available online as PDFs at the Canadian Soil Information System (CANSIS) website.
When I want information on soils of a specific area of Manitoba, I have always been able to find some very good information.
The bottom line
The bottom line is soil association or series names are needed to make soil fertility, cropping and other recommendations for farm management. For example, if we want to know where the very serious soil potassium deficiencies are in Western Canada, the first place to look is the Almassippi sandy loam soils of Manitoba and, particularly, the Carrot River very fine sandy loam soils of Saskatchewan. Soil maps provide that information.
In recent years, there has been too much research published without sufficient naming of soils, such that the data cannot be properly interpreted for areas other than the exact field site. If you hear a presentation about an agronomic practice, the speaker may indicate the area where the work was carried out. If they do not identify the soil association or series they are working on, ask for that information. This will let you know if the information applies to you or not, as long as you know what you are farming, or your agronomist should know.
*Update: When this column was first posted online, I stated Manitoba did not have soil survey maps with digital access. Readers have informed me that is not true. See the link here at agrimaps.gov.mb.ca/agrimaps/.
When I click on the link, it brings up a very nice map of Manitoba on a recent air photo base. In “Find Address or Place,” I input the metropolis of Stockton and an excellent air photo pops up with Stockton and legal townships shown. A zoom in brings up legal locations with sections shown.
I immediately go to N 1/2 30 7 15 W1 — the half section my Dad was raised on. It was called Evergreen Farm and the spruce are still in place just west and south of the farmstead. I also saw several irrigation pivots just south of Stockton. I assume the water must be coming from the southwest edge of the famous Assiniboine Delta aquifer.
What a great learning experience. Thanks to Manitoba for that great resource. I have not yet been able to bring up the soil maps, but that is due only to the geriatric factor. A little time and help and that will come.
Many thanks to the readers who pointed out the error and my apologies for not checking back first.