2017 Soybean Seasonal Summary

Table of Contents

  1. Summary
  2. Crop Rotation
  3. White Mould
  4. Variety selection
  5. Fertility

Technical information can be obtained at the OMAFRA Field Crops Webpage. Referenced OMAFRA Publications include the Agronomy Guide for Field Crops (Publication 811), the Field Crop Protection Guide (Publication 812), Guide to Weed Control (Publication 75), and Ontario Weeds (Publication 505). These can be obtained from your OMAFRA Resource Centre, or by calling 1-800-668-9938.


Soybeans are the largest field crop grown in the province annually. The 2017 Ontario crop was the largest ever grown at 3.1 million acres. A wet spring, followed by a relatively cool summer resulted in challenging planting conditions, reduced stands, slow growth, and considerable white mould pressure, particularly in eastern Ontario. Fortunately, above average fall temperatures matured the crop in good time to allow for optimal winter wheat seeding. Yields from as low as 9 bu/ac to over 70 bu/ac were reported across the province. Some regions started the season with wet conditions but then turned dry in August and September resulting in poor yields. Despite these challenges, overall yields turned out better than expected for many. With 57% of insured growers having reported to date, the provincial average for 2017 is 44.1 bu/ac. The 10 year average for those reported acres is 44.8 bu/ac. The 5 year average for the province is 46.2 bu/ac, not including 2017.

The tremendous success of soybean production in Western Canada will likely result in more soybeans being grown in Western Canada next year than all of Ontario, Quebec, and the Maritime provinces combined. Manitoba grew the sixth consecutive year of record production and increased acreage to 2.2 million in 2017. Saskatchewan tripled acres in 2017 to 846,000 acres. Soybeans are now the third largest field crop in Canada in terms of farm cash receipts.

Crop Rotation

One of the challenges holding back soybean yields in Ontario is the huge acreage planted every year. Excessive soybeans in a crop rotation can lead to decreased soil health and increased pressures from insects and diseases ultimately lowering yields. In some areas soybeans are grown every second year or two out of three years. Continuous soybeans are relatively rare but can be found in the southwest part of the province. Continuous soybeans are extremely detrimental to yields and soil health and research shows a reduction of 8 bu/ac even in the absence of a disease breakout. If a white mould or Soybean Cyst Nematode outbreak occurs a yield reduction of 30 bu/ac is possible. The agronomic value and extra yield of a good crop rotation should always be considered when planning next year's crop. Cover crops are an important management tool to maintain soil health but cannot take the place of a good crop rotation. A corn, soybean, wheat crop rotation is still considered the optimal rotation in Ontario. Adding cover crops to a less diverse crop rotation will not make up for a poor crop rotation.

White Mould

Most of the southwestern part of the province does not face severe white mould pressure consistently. This was the case again in 2017 when severe white mould outbreaks were isolated to specific fields. However, there are growers that face significant white mould pressure almost every year, especially in eastern Ontario (Figure 1). Twenty years ago it was not standard practice to apply a foliar fungicide on soybeans to control white mould. Today, fungicides are becoming an important tool in the suppression of white mould. Irrigated research trials conducted by Chris Gillard at the University of Guelph, showed that an early application of a foliar fungicide could increase yield by up to 15 bu/ac when white mould was present. When spraying to suppress white mould, the most economical timing appears to be relatively early during the flowering period. If white mould is not the target disease later applications can be more effective in increasing yields depending on the disease. Spraying during the vegetative stages is too early and provides little benefit. Make careful note of which fields were affected this year and plan accordingly for the next susceptible crop. Planting a crop such as corn and wheat to provide a two year break from a susceptible crop, will go a long way in reducing disease pressure. There are large differences in variety tolerance to white mould so careful variety selection is important. Seeding rates should be kept low in fields with a history of the disease and the use of wider rows will help to lower moisture levels within the canopy. No-till soybeans are usually far less impacted from white mould than fields that are tilled.

Figure 1. Soybean plant infected with white mould.

Figure 1. Soybean plant infected with white mould.

Text equivalent to graphic

Variety selection

Soybean variety selection continues to be one of the most important management decisions a grower can make to achieve high yields. Each year dozens of new varieties come to the marketplace. The Ontario Soybean and Canola Committee conducts independent performance trials across the province. Results from these trials can be found at gosoy.ca. Within a single test, yield differences of over 10 bu/ac between varieties are not uncommon. Generally longer maturing varieties yield about 0.5 bu/ac more for each day they take longer to mature in the fall, particularly in short season areas. See the yield-maturity graphs at gosoy.ca. For fields not intended for winter wheat choosing a longer season variety is a cost effective way to increase yields.


Since 1981 corn yields have increased by 80%, soybeans by 35%, and winter wheat by 65%. Higher yields remove more nutrients. There is concern that insufficient nutrients are being applied to maintain high yields, especially for soybeans. Maintaining phosphorous and potassium levels represents a significant expense to growers, and can pose economic (ie. land rental) and environmental (phosphorous runoff) risks if soil test values are built excessively high. However, not applying sufficient fertilizer will reduce yields and economic sustainability. Regular soil testing is the only way to manage soil nutrients properly. Ontario research has shown that fields low in both P and K will yield 8 bu/ac less than fields with adequate soil fertility. Therefore, maintaining soil test values at a reasonable level is the most economic and environmentally sound management strategy long term.

For more information:
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E-mail: ag.info.omafra@ontario.ca