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Soil Salinization Indicator

Risk of Soil Salinization indicator assesses and tracks changes in the potential for salinization – the accumulation of soluble salts in portions of the landscape – attributed to changes in agricultural land use and management practices.

Salinization is a particular issue in areas like the Canadian Prairies that have moisture deficits and high annual evaporation/transpiration rates, and where ground water may naturally have higher concentrations of mineral salts. For this reason, the indicator has been developed to reflect the risk of salinization in Alberta, Saskatchewan and Manitoba.

Agriculture can exacerbate salinity; practices that leave the soil exposed during rainfall or runoff events, such as summerfallow (a practice of leaving fields bare) or intense tillage, can worsen salinization risk. Agriculture can also be affected by salinization. Certain crops will not grow in even lightly saline soils, and soils that are highly saline are not suitable for any type of crop.

What are Agri-Environmental Indicators?

Agri-Environmental Indicators (AEIs) are measures of key environmental conditions, risks, and changes resulting from agriculture and of the management practices that producers use to mitigate these risks. They help explain:

Agriculture and Agri-Food Canada (AAFC) has been compiling and analyzing data and reporting on AEIs since 1993, but we use data from as far back as 1981. The Risk of Soil Salinization Indicator is one of several national indicators being tracked by AAFC.

Overall state and trend

In 2011, the Prairie Region as a whole demonstrated a very low risk of salinization. Between 1981 and 2011, the risk of salinization within the Prairies has declined significantly. Use the interactive map below to zoom in and explore different regions, and click the play button to explore the changes in salinization risk since 1981. Note that all the Prairie Provinces show a low risk or very low risk and that this risk has declined since 1981. This is attributed to the uptake of beneficial management practices such as conversion from annual crop to perennial cover, no-till or minimum-tillage, and the cessation or reduction in summerfallow.

Figure 1: Risk of Soil Salinization on the Canadian Prairies

Legend: legend

Use the interactive map in Figure 2 to explore the change in salinization risk between 1981 and 2011. It is apparent that the reduction in risk is occurring throughout the Prairies, but is most evident in Saskatchewan.

Figure 2: Change in Soil Salinization risk on the Canadian Prairies, 1981 to 2011

Legend: legend

Risk of Soil Salinization performance index

The state and trend of the soil salinization indicator can also be seen in the performance index below.

Figure 3: Risk of Soil Salinization Index
Description of this image follows.
Description - Figure 3
Year Index Value
1981 85
1986 86
1991 87
1996 88
2001 90
2006 91
2011 93

As illustrated by the performance index above, in 2011 the state of the environment from the standpoint of the risk of salinization on farmland in the Canadian Prairies was "Desired". The index illustrates an upward trend, from an index value of 85 in 1981, to an even higher value of 93 in 2011, representing a declining risk of soil salinization across the Prairies.

The index tends to aggregate and generalize trends and so should be viewed as a policy tool to give a general overview of state and trend over time.

How performance indices are calculated

Specific trends

Saskatchewan demonstrates a dramatically lower risk of salinization

Although changes were observed in all Prairie Provinces, the greatest changes occurred in Saskatchewan where the area of summerfallow decreased by more than 5 million hectares and the area of permanent cover increased by more than 3 million hectares. Changes in land use and management practices over from 1981 to 2011 have lessened the risk of salinization and indicate a trend towards improved soil health and agri-environmental sustainability.

Click and drag the vertical bar on the map below to see the difference in risk of salinization in Saskatchewan between 1981 and 2011.

Figure 4: Change in Soil Salinization risk in Saskatchewan, 1981 to 2011
1981 2011

Legend: legend

Reasons for this trend

The Prairie-wide improvement in salinization risk has been largely attributed to the steady reduction in the area of summerfallow, which decreased by over 7 million hectares (a 78% reduction) from 1981 to 2011 (see figure 5 below), and to an increase in area of permanent cover of 4.8 million hectares (a 14% increase) over the same period. This reduction is particularly dramatic in Saskatchewan, which has experienced the largest decline in summerfallow area, from nearly 6.7 million hectares in 1981, down to just 1.4 million hectares in 2011.

Figure 5: Area in summerfallow on the Canadian Prairies from 1981-2011
Description of this image follows.
Description - Figure 5
Province 1981 1986 1991 1996 2001 2006 2011
Alberta 15,817,907.2 15,443,400.1 15,557,027.7 15,806,103.69 16,465,899.9 16,735,218.11 16,592,120.26
Saskatchewan 11,857,220.93 11,358,032.54 11,234,149.62 11,738,527.82 12,481,091.35 14,196,070.83 15,097,800.69
Manitoba 5,957,898.6 5,985,232.442 6,067,038.327 6,140,213.444 6,339,267.408 6,547,413.165 6,718,449.617
Prairies 33,633,026.73 32,786,665.09 32,858,215.64 33,684,844.95 35,286,258.65 37,478,702.1 38,408,370.57

The decline in summerfallow throughout the Prairie Region is a result of a number of factors that include:

Why this indicator matters

Salinization not only reduces the yield of agricultural crops but also limits the range of crops that can be grown, thereby reducing the potential economic returns to farmers. For example, beets and edible beans are considered to be very sensitive to salts, and barley is able to tolerate weak salinity better than wheat. In 1998, losses to the income of Canadian farmers as a result of soil salinity were estimated at $257 million annually (Forge 1998).

While salinization risk has lowered across the Prairies over the last few years, it is still a localized issue of concern for some producers. Agriculture has the potential to mitigate by implementing beneficial management practices.

Beneficial Management Practices

As it is linked so closely to soil-water conditions salinization can be mitigated or avoided through appropriate soil-water management. Beneficial management practices to reduce excess water, therefore controlling excess salt movement, include:

  1. Reducing summerfallow and intense tillage, and shifting to no-till or reduced tillage
  2. Increased planting of perennial forages, pastures and tree crops,
  3. Managing snow to provide a more uniform distribution of melt water (preventing large drifts); and
  4. Using fertilizers and manure effectively to support healthy crops.

How performance indices are calculated

The agri-environmental performance index shows environmental performance state and trends over time, based on weighting the percentage of agricultural land in each indicator class, such that the index ranges from 0 (all land in the most undesirable category) to 100 (all land in the most desirable category). The equation is simply "(% in poor class multiplied by .25) plus (% in moderate class multiplied by .5) plus (% in good class multiplied by .75) plus (% in desired class)." As the percentage of land in the "at risk" class is multiplied by zero, it is not included in the algorithm.

The table below shows the index classes. The index uses the same five-colour scheme as the indicator maps whereby dark green represents a desirable or healthy state and red represents least desirable or least healthy.

The index classes
Scale Colour scheme Class
80-100 Dark green Desired
60-79 Light green Good
40-59 Yellow Moderate
20-39 Orange Poor
0-19 Red At risk

The index tends to aggregate and generalize trends and so should be viewed as a policy tool to give a general overview of state and trend over time.

Related indicators

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