Conventional tillage: How conventional is it?
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Nancy Hofmann, Environment Accounts and Statistics Division
Tillage involves preparing soil for planting or seeding by plowing, cultivating or otherwise turning it. Tillage loosens and aerates the soil, which allows for the deeper penetration of roots. It controls weeds and mixes organic matter, fertilizer and manure with the soil. However, tillage can contribute to the loss of soil moisture, lead to increased wind and water erosion and consume significant amounts of fuel.
In recent years, farming practices have changed due to the need to reduce water loss, soil erosion and costs. What was once the conventional approach to tillage is now less common, particularly in the Prairie provinces.
What you should know about this study
This study uses tillage data from the Census of Agriculture. Since 1991, the Census has tracked three types of tillage. No-till and conservation tillage are relatively new concepts and data is only available starting in 1991. Data are presented by province and by sub-sub-drainage area.
Conventional tillage, conservation tillage and no-till (or zero-till) are defined by the amount of crop residue left on the ground. Crop residue is the vegetative material, often referred to as trash or litter, left after a crop has been harvested. It can include straw, stubble, leaves, stalks, etc. Some crops, such as corn, typically produce more residue than others.
Conventional tillage incorporates or buries most of the crop residue into the soil. Typically this approach involves multiple passes in fields. The moldboard plow is often used first, followed by other implements. Since this method plows under much of the crop stubble, it leaves the surface relatively bare and without cover protection.
Tillage that retains most of the crop residue on the surface and involves minimal tillage is known as conservation tillage. Some straw, stubble, leaves, and other residue are visible on the surface.
Seeding that involves direct seeding into crop residue/soil is known as no-till or zero-till. The no-till approach avoids any mechanical tillage of the soil and attempts to keep soil disturbance to an absolute minimum. In contrast to the multiple passes of equipment in the conventional approach, no-till can involve just one pass through the fields for planting.
Which method is best? Advantages and disadvantages
Conventional tillage becoming less conventional
No-till gaining popularity
Modest growth nationally in conservation tillage
Few areas use only conventional tillage
Farmers in Canada use conventional tillage, conservation tillage and no-till seeding practices (see Textbox for definitions). Each approach has advantages and disadvantages, but the best method depends on specific conditions such as climate, soil and crop types to be planted.1
One advantage of conventional tillage is that the needed machinery is widely available and the techniques are well-known to farmers. Newer methods may require the purchase of new equipment or attachments and often a learning effort on the part of the farmer.
Conventional tillage can increase porosity and loosen soil, allowing for good air exchange and root growth. It is also an effective way of incorporating manure and breaking up sod fields.2 As well, soils that are tilled typically warm faster in the spring than those with less tillage.
However, the limited amount of residue left on fields from conventional tillage and to a lesser extent conservation tillage leaves soils more vulnerable to wind and water erosion. Crop residue protects the soil surface and slows run-off (increasing water infiltration). Organic matter in crop residue also helps trap moisture, reduce water evaporation and prevent soil from drying out. In areas where soil moisture is a limiting factor, reducing tillage can be very beneficial at limiting moisture loss and thus improving yields.3
The greater the level of tillage, the greater the loss of soil organic matter. Organic matter is important for supporting beneficial biologic activity such as bacteria, fungi and earthworms that help cycle nutrients and increase the speed of pesticide breakdown. Soil organic matter also plays a role in climate change, since organic matter stores carbon.
By lowering the number of passes through the fields with conservation tillage or no-till, farmers realize significant savings in fuel and labour. Nationally, total fuel expenditures and repair costs on farms using no-till systems were approximately one third that of those in typical conventional tillage in 2006.4 Reduced use of fuel not only lowers costs, but also reduces air pollution.
Areas at a high risk of erosion, such as sloping land, land exposed to wind erosion and land with light-textured soils, are better suited to reduced tillage systems. Some crops are also more easily grown than others using reduced tillage. Cereal grains, oil seeds and beans are far more common candidates for these new practices than corn or potatoes. In fact, it is typically believed that potatoes can not be effectively grown with a no-till approach,5 but this may change as a result of on-going research.
Between 1991 to 2006, the total area prepared for seeding in Canada using the conventional approach dropped by 60% or 12 million hectares—an area over 2.5 times the size of Switzerland. By 2006, conventional tillage had lost its status as the number one tillage option, and was the second most popular system behind no-till—only slightly more popular than conservation tillage.
With the exception of Newfoundland and Labrador, all provinces experienced a decline in the total area seeded using conventional tillage. The largest drops occurred in Saskatchewan and Alberta, where the area tilled by conventional tillage dropped by about 70%, or almost 10 million hectares.
Nationally, conventional tillage was practiced on 28% of all land prepared for seeding in 2006; however, there were significant provincial differences. Conventional tillage ranged from a high of 88% of the seeded area in Newfoundland and Labrador to a low of 18% in Saskatchewan (Table 1).
Table 1 Percentage of total land prepared for seeding, 1991 and 2006
Conventional tillage was the most common approach in the Atlantic provinces, Quebec, Ontario, Manitoba and British Columbia. With just 25%, Alberta had the second lowest proportion of land prepared for seeding using conventional tillage, behind Saskatchewan. These two Prairie provinces greatly influence the national rates since they contain a significant portion of Canada's seeded land. Seven out of every ten hectares of seeded land was found in either Alberta or Saskatchewan in 2006.
Nationally, the proportion of land prepared for seeding using no-till practices increased from 7% to 46% from 1991 to 2006 (Table 1). The largest gains in no-till occurred in Saskatchewan and Alberta, but no-till seeding also increased rapidly in Ontario, Manitoba and British Columbia. In Saskatchewan, the use of no-till increased from 10% of the total area prepared for seeding in 1991 to 60% in 2006, while in Alberta it rose from 3% to 48%.
The Prairies embrace no-till
Many farmers have recognized the environmental and financial benefits that no-till provides for their crops. Map 1 presents tillage practices by drainage area6 and portrays the geographic concentration of no-till in the relatively dry Prairie region.
British Columbia, Alberta, Saskatchewan and Nova Scotia are home to 55 sub-sub-drainage areas (SSDA) that used the no-till approach for 56% or more of the total area prepared for seeding. Over three-quarters of these 55 SSDAs were found in Saskatchewan alone.
Generally speaking, in Eastern Canada and British Columbia, most SSDAs areas reported between 0 and 30 percent of the total area seeded using the no-till approach. However, exceptions occurred in parts of British Columbia, Southern Ontario, and central Nova Scotia. Alberta had the most variety with some clusters of drainage basins embracing no-till, while others used it to a lesser extent (Map 1).
In 2006, 26% of the total area prepared for seeding in Canada was completed using conservation tillage, up just two percent from 1991. Conservation tillage, the second most popular approach in 1991, dropped to third place in 2006, behind no-till and conventional tillage.
In 2006, 337,000 more hectares were seeded using conservation tillage than in 1991. Significant gains in the area tilled using conservation methods occurred in Ontario (225, 000 ha), Quebec (217,000 ha), Alberta (164,000 ha) and Manitoba (162,000 ha), but these increases in conservation tillage were offset by a decline of 472,000 ha in Saskatchewan.
Across the country, there were just 27 SSDAs where all land was prepared for seeding using conventional tillage—with no conservation tillage or no-till seeding. These SSDAs were scattered across with country.
No one tillage system is best for all Canadian farms because there is so much variability in soils, crops and climate. The tillage system used to prepare a field for seeding is based on various factors including the approach's compatibility with the farm's soil types, soil moisture levels, slopes, drainage and climate. The effect on erosion control, timeliness, weed control, insects, diseases and the profitability of the farm operation are also important considerations. The cost of fuel has increasingly become a principal factor in the selection of a tillage approach.
For further reading please visit: Ontario Ministry of Agriculture, Food and Rural Affairs, 2002, Agronomy Guide for Field Crops,
www.omafra.gov.on.ca/english/crops/pub811/p811toc2.htm (accessed July 8, 2008).
Alberta Agriculture and Rural Development, 2006, Beneficial Management Practices: Environmental Manual for Crop Producers in Alberta – Chapter 3 Cropping Practices,www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex9330 (accessed July 9, 2008).
- Ontario Ministry of Agriculture, Food and Rural Affairs, 2002, Soil Management and Fertilizer Use: Tillage Systems, www.omafra.gov.on.ca/english/crops/pub811/2tillsys.htm (accessed July 8, 2008).
- Ontario Ministry of Agriculture, Food and Rural Affairs, 2008, "Soil management," Field Crop Production: Understanding the Basics, www.omafra.gov.on.ca/english/environment/field/basics.htm (accessed July 8, 2008).
- Statistics Canada, 2006 Census of Agriculture, special tabulation.
- Ontario Ministry of Agriculture, Food and Rural Affairs, 2008, "Soil management," Field Crop Production: Understanding the Basics, www.omafra.gov.on.ca/english/environment/field/basics.htm (accessed July 3, 2008).
- Drainage areas, also called watersheds or drainage basins, are areas where all contributing surface waters share the same drainage outlet. Drainage areas channel runoff from precipitation and snow melt into stream flow. The sub-sub-drainage area is the smallest unit in the National Hydrological Network of Canada.