Organic Wheat Variety Selection

Wheat is an important crop in an organic rotation. It is often grown after a green manure or forage year to maximize available nitrogen uptake and profitability. The following data are sourced from the Natural System’s Agriculture Lab at the University of Manitoba from checks used within organic trials. Refer to your province’s seed guide for reliable disease and maturity ratings. Performance data from organic trials (i.e. from provincial seed guides) provides you with the best source of information; however, variety performance under conventional management (using chemical weed control, and synthetic fertilizers) is not representative of organic growing conditions.

Things to Consider

Quality: Protein and Bushel Weight

Bushel weight (or test weight) is an indicator of grain density. For example, grades 1 to 3 for Canada Western Red Spring (CWRS) wheat require a minimum test weight of 69-75 kg/hL, respectively. Generally, milling quality wheat requires a minimum of 10% protein for No.1 grade, and a protein level of 13.5% or higher may receive a premium¹.

Height

Modern wheat varieties incorporate semi-dwarf genes to keep the plant shorter while maintaining yield potential. For example, AAC Brandon contains semi-dwarf genes. Taller plants may be advantageous for weed competition under organic management. However, many taller varieties are very prone to lodging, especially if the crop is grown in a high fertility year.

Yield

The following yield data are sourced from organic trials in Manitoba and Alberta. The stars representing the location of sites are shown in Figure 1. Although only a few sites are represented, they span multiple years (2017-2022). Yield data have been organized into ‘low-yielding’ and ‘high-yielding’ sites. This has been done to ensure a true representation of genetic potential in optimal years versus tough years.
Figure 1. Locations of organic wheat trials, 2017-2022

Low-Yielding Sites

Carman 2021, Roblin 2020, 2021, Libau 2020, 2021, Oxbow 2020, 2021 (7 site years). Low yield was due to drought or very low phosphorus levels.

High-Yielding Sites

Carman 2020, 2022, Edmonton 2020, 2021, 2022, Libau 2022, Roblin 2022 (7 site years)

Other Yield Data

Other varieties that have been tested but not consistently across the site years mentioned above. Data provided from sites: Carman 2019, Swift Current 2019, Edmonton 2019 (3 site years)

Organic Oat Variety Selection

Oats are a great option to include in an organic crop rotation. They are very competitive against weeds and yield well under organic conditions.
The following data are sourced from the Natural System’s Agriculture Lab at the University of Manitoba from variety checks used in organic trials. Refer to your province’s seed guide for reliable disease and maturity ratings. Performance data from organic trials (i.e. from provincial seed guides) provides the best source of information – however, variety performance under conventional management (using chemical weed control, and synthetic fertilizers) is not representative of organic growing conditions.

Things to Consider

Quality: Grain Buyer Considerations

When it comes to selling your oats, quality is just as important as yield. Varieties recommended or that are acceptable or under review by Canada’s largest buyer of organic oats, Grain Millers¹, are shown in for different Prairie production zones (Figure 2) in Table 1.

Quality: Bushel Weight and Percentage Plumps

Bushel weight (or test weight) is an indicator of grain density. Grain density is dependent on growing conditions in combination with genetics. Percentage plumps is an indicator of the proportion of grain with plump kernels versus thin kernels; this can also be an indicator of overall seed size.

Height

Height can be an advantageous trait for weed competitiveness, shading out the competition earlier in the season. However, taller plants are prone to lodging under fertile, high moisture conditions. Most modern oat varieties are screened for lodging resistance, but choosing a taller variety increases the risk of lodging.

Yield

The following yield data are sourced from organic trials in Manitoba and Alberta. Site locations are shown in Figure 3. Although only a few sites are represented, the trials span multiple years (2017-2021). Data have been organized into ‘low-yielding’ and ‘high-yielding’ sites. This was done to ensure a true representation of genetic potential in years with optimal growing conditions versus tough years.

Figure 3. Locations of organic oat trials, 2017-2022

Low-Yielding Sites
Carman 2020, 2021, Glenlea 2021, Robin 2021, Libau 2019, Somerset 2017 (6 site years). Low yield was due to drought or very low phosphorus levels.

High-Yielding Sites

Carman 2017, 2019, 2020, Roblin 2020, Lacombe 2019 (5 site years).

Other Yield Data
Other varieties that have been tested but not consistently across the site years mentioned above. Data provided from sites: Carman 2015, 2017, 2017 (late seeded), Somerset 2017 (4 site years).

Soybean Variety for Organic Production Systems

Soybean is a warm season crop, but new varieties have allowed Manitoba growers to produce high yielding short season varieties. However, special considerations are required given our colder growing conditions. Soybeans should be placed near the lower fertility ‘end’ of a rotation. Lower soil nitrogen gives the N-fixing qualities of soybean a competitive advantage over weeds. But don’t forget to inoculate with rhizobium!

Things to Consider

Soybean Maturity

The most critical part of choosing the right variety is choosing the right maturity rating for your area. Usually, the longer the soybean takes to mature, the higher the yield potential. However, if the crop undergoes frost damage prior to seed fill and maturity, seed fill stops, and yield is severely affected. To grow a successful soybean crop, you should be aware and understand the maturity zone system.

Manitoba Maturity Zones

Manitoba Agriculture has organized soybean growing zones into four categories: very early-, early-, mid-, and long-season (Figure 4). The categories were created based on long-term heat units and frost-free periods. Each zone indicates the longest season varieties that can be grown in that region.

Variety Maturity Group

Varieties fit into each soybean growing zone based on their relative days to maturity. The soybeans best suited to Manitoba are in the 000-00 maturity group. The number after the “.” indicates an extra day to maturity.

Varietal Characteristics

Soybeans are not competitive with weeds, especially early in the growing season. Soybeans are a warm-season crop, and often cooler season weeds such as mustard and lamb’s quarters that are more accustomed to our cool growing conditions, outcompete them early in the season, severely affecting yield.

Early Vigour

Soybeans that can put on high growth early in the season are valuable for weed competitiveness. While some research has indicated that earlier maturing soybeans put on greater growth earlier in the season than later maturing varieties, organic soybean variety trials in Manitoba did not show that height or biomass early in the season resulted in higher yields³. Variety guides often don’t report early vigour. It would be more important to select a variety with high yield potential, in combination with your proper maturity group and market goals.

Height

Height is advantageous for weed competition4. Yield and soybean height were significantly correlated in organic soybean variety trials in Manitoba³, thus selecting a taller variety may be useful in organic soybean production.

Height to Lowest Pod

The length from the ground to the first pod affects harvestability. Pods higher off the ground are more likely to be harvested and less likely to be stained – a factor that can downgrade soybean quality.

Hilum Colour

The hilum is the point on the seed where it connects to the pod. Hilum colours can be eight different colours: black, imperfect black, gray, dark brown, medium brown, imperfect yellow, and yellow. Hilum colour may cause the milk and meal of the soybean to have gray shades, therefore yellow, imperfect yellow, and clear are usually preferred for food-grade soybeans and export markets.

Yield
The following data are sourced from organic non-GM soybean performance trials that took place across southern Manitoba in 2014 and 2015 (Table 2). All soybean variety hilums are either yellow, imperfect yellow, or clear. Soybean yield was comparable to conventional yields at certain sites. However, an early killing frost at one site reduced yield in some varieties dramatically. The killing frost exemplifies the importance of selecting the correct maturity group. Figure 5 summarizes data from all sites and years. Somerset (2014) and Swan Lake are omitted due to frost effects.

Table 2. Organic soybean variety trials in southern Manitoba: Days to Maturity, Yield Indices, Plant Height, and Pod Height Summary.

Varieties can only be compared with each within each test area. Yield index is the percentage of the average yield of all varieties grown in a test area (refer to the bottom of each site’s column for that site year’s average yield). Days to maturity, plant height, and pod height are averaged across all sites and years.

Other Considerations

Other variety considerations that were not evaluated in this research are iron deficiency chlorosis, soybean cyst nematode resistance, and phytophthora root rot resistance. This information is provided in Seed Manitoba. Some other sources when selecting:

• Company trials and information
• Seed Manitoba
• Past trials through Manitoba Soybean and Pulse Growers
• On-Farm Experience

Summary

While choosing the right variety for your farm and market is important, it cannot substitute for good agronomy. A diverse crop rotation, adequate nutrients, and agronomic interventions such as a clean seedbed, high seeding rates, increased seed size, and good weed control (pre-emergence harrowing) is essential for crop success. Choosing the correct variety for your farm is only part of the journey that leads to a successful crop. Proper early season weed control (clean seedbed, blind harrowing, and inter-row cultivation) is key. For more information on growing a successful organic soybean crop, check out the Natural Systems Agriculture research report here.

References

1. Canadian Grain Commission. 2022. Official Grain Grading Guide.
   https://www.grainscanada.gc.ca/en/grain-quality/official-graingrading-
   guide/pdf/oggg-2022-23-e.pdf
2. Grain Millers. 2022. Recommended milling oat varieties. http://www.grainmillers.com/wp-content/uploads/2022/01/
   Recommended-Varieties-Canada-2022.pdf
3. Carkner, M.K., Entz, M. H. 2017. Growing environment contributes more to soybean yield than cultivar under organic management. Field Crops Research. 207:42.51.
4. Jannink, J.-L., Orf, J.H., Jordan, N.R., Shaw. 2000. Index selection for
   weed suppressive ability in soybean. Crop Science. 40:1087-1094.