Soil Cover Indicator

The Soil Cover Indicator summarizes the effective number of days in a year that agricultural soils are covered by vegetation, crop residue or snow, thereby protecting them from degradation processes that affect bare soils, such as wind and water erosion, organic matter depletion, structural degradation and loss of fertility. This indicator has tracked soil cover associated with Canadian agricultural activities from 1981 to 2011, and reports them in terms of Soil Cover Days.

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:

  • how the agriculture sector is performing,
  • why it is performing as it is,
  • whether that performance is satisfactory, and
  • how it is likely to evolve in the future.

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

Overall state and trend

Soil cover has been increasing on agricultural lands in Canada. Despite shifts from pasture and forage production to annual cropping in some parts of the country, the national average increased from 268.5 soil cover days in 1981 to an average of 288.8 soil cover days in 2011. The greatest increase occurred in the Prairie Provinces, particularly in Saskatchewan. This improvement can mainly be attributed to a reduction in summerfallow – a practice of leaving fields bare, along with a shift to reduced tillage and no-till practices in this region.

Use the interactive map below to zoom in and explore different regions. Note that despite the agricultural intensity of the region, the Prairie Provinces show a moderate level of soil cover, with only a few pockets of lower levels; and the Lake Erie Lowland region of southeast Ontario contains some pockets of very low soil cover.

In addition to exploring the 2011 values, click the play button to view changes over time. Since 1981, there has been a significant increase in soil cover across Canada, particularly evident across the Prairies. The Lake Erie Lowland region, while still considered to have very low soil cover levels, has been improving, and the St. Lawrence Lowlands region of Quebec has been declining over this time.

Generally speaking, the large improvements in the Prairies can be mainly attributed to the reduction in summerfallow as well as an increase in reduced tillage and no-till practices, which have increased plant residues, reducing the amount of bare soil exposed to degradation. The decline in soil cover elsewhere can be explained by shifts in cropping practices and crop types. Since 2006, the sharp decline in beef cattle production, as well as a longer-term decline in dairy herds since 1981 has reduced the area under pasture and forage production. Much of the area previously dedicated to these land uses have been converted to annual crops, such as corn, which do not provide as much cover as perennial crops. In spite of this however, overall trends are improving on a national basis.

Figure 1: Soil Cover Days in Canada, 1981-2011

Legend: legend

Use the interactive map in Figure 2 to explore the change in soil cover days between 1981 and 2011. It is apparent that the increase in soil cover is most significant in the Canadian Prairies.

Figure 2: Change in Soil Cover Days, 1981 to 2011

Legend: legend

Soil cover performance index

The state and trend of the Soil Cover Indicator can also be seen in the performance index below.

Figure 3: Soil Cover Index
Description of this image follows.
Description - Figure 3
Year Index Value
1981 32
1986 34
1991 34
1996 39
2001 44
2006 49
2011 51

In 2011, the state of the environment, as it relates to soil cover resulting from farming activities in Canada, was in the "Moderate" category. The index illustrates an upward trend, from an index value of 32 in 1981, to a higher value of 51 in 2011, demonstrating a steady improvement and an increase in soil cover over this 30-year period. From 1981 to 2011 average levels of soil cover in Canada increased by 7.6%. This national-scale improvement came about primarily as a result of widespread adoption of reduced (conservation) tillage and no-till, as well as decreases in the use of summerfallow in 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

This section highlights a few other trends of interest. In some cases, these are occurring in certain regions and in others they are affecting certain sectors, such as the beef or dairy industries. This is not an exhaustive list; additional findings can be found in the full publication: Environmental Sustainability of Canadian Agriculture, Agri-Environmental Indicator Report Series - Report #4 .

Trend 1 – Prairie farmland sees a significant increase in soil cover days since 1981

The Prairie Region has seen significant improvements in soil cover over the past 30 years. You can explore these improvements in the swipe map below.

Figure 4: Change in Soil Cover Days in the Prairies, 1981-2011.
1981 2011

Legend: legend

Reasons for trend 1

The primary reason for the improvement in this indicator in Canada is due to the shift away from summerfallow and intensive tillage in the Prairie region. Figure 5 shows the change in percentage of farmland – between 1981 and 2011 – under summerfallow, as well as under no-till for the Prairies (Alberta, Saskatchewan and Manitoba) as well as for Canada as a whole. Because the Prairie region accounts for over 85% of farmland in Canada, changes in these provinces significantly impact the national averages.

Figure 5: Trends in summerfallow and no-till in the Prairies, 1981 to 2011. Note that Census data for tillage practices are available from 1991 onwards only.
Description of this image follows.
Description - Figure 5
Percentage of farmland under no-till
1981 1986 1991 1996 2001 2006 2011
Manitoba 5 9 13 21 24
Saskatchewan 10 22 39 60 70
Alberta 3 10 28 48 65
Canada 7 16 30 46 56
Percentage of farmland under summerfallow
1981 1986 1991 1996 2001 2006 2011
Manitoba 8 7 4 4 3 2 1
Saskatchewan 26 20 20 16 11 8 5
Alberta 12 10 8 7 6 4 2
Canada 14 12 11 9 6 4 3

Trend 2 – Parts of Eastern Canada see slight reduction in soil cover

While the national trend for soil cover is extremely positive, this has been slightly offset by localized decreases in soil cover in parts of eastern Ontario and southern Quebec, and in parts of the Maritimes. You can explore this trend using the swipe map below.

Figure 6: Soil Cover change in Eastern Canada, 1981 to 2011
1981 2011

Legend: legend

Reasons for trend 2

Since 1981, parts of the St. Lawrence Lowlands in eastern Ontario and western Quebec showed decreases in soil cover of greater than 10 days. These areas underwent significant changes in crop distribution, with relatively large shifts from pasture and forage production to annual crops during the period under study. Much of this change occurred after 2006, reflecting the decline in beef cattle production. Similar trends occurred in parts of the Maritimes, notably in PEI, and for the same reason. You can see the trends in annual crops in the figure below.

Figure 7: Trends in annual crops in Eastern and Atlantic Canada, 1981 to 2011
Description of this image follows.
Description - Figure 7
1981 1986 1991 1996 2001 2006 2011
Ontario 59 62 61 64 65 65 70
Quebec 32 35 39 43 51 50 53
New Brunswick 33 34 36 36 36 35 36
Nova Scotia 20 17 17 16 16 15 17
Prince Edward Island 55 58 59 62 60 57 62
Newfoundland and Labrador 16 11 10 12 12 14 10

Why this indicator matters

Soil cover has implications for a number of environmental processes and conditions relating to overall soil health, including organic matter content and soil susceptibility to erosion, as well as for broader environmental issues such as wildlife habitat and water and air quality. Soil cover also has implications for land productivity, crop yield and quality.

Agriculture has the potential to mitigate by implementing beneficial management practices (BMPs) that increase soil cover and by limiting practices (such as summerfallow) that decrease soil cover.

Beneficial Management Practices

In the Prairies especially, producers can increase soil cover by reducing summerfallow and tillage intensity and by converting annual crops to perennial cropping systems. There has been a national increase in low-residue crops such as potatoes, canola, soybeans, vegetables and nursery crops, and this trend is expected to continue. Planting a green manure crop or a winter cover crop where feasible as soon as possible after harvesting would provide a greater degree of soil cover for these crops during the long period between harvesting in the fall and planting in the spring. This may become especially important if climatic changes reduce the number of days of soil protection afforded by snow or if extreme weather events become more common in the spring before planting, when the soil is particularly vulnerable to degradation through erosion. Other means of increasing soil cover would be to consider intercropping low cover row crops with suitable companion plants. In some cases, these plants might provide additional revenue to producers.

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

Additional resources and downloads

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