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Soybean – Storage and Grading



  • Proper soybean storage management is important to prevent a grade decrease.
  • If harvest occurs when soybean moisture is above 13%, soybeans should be conditioned to bring moisture down.
  • Crops stored under cool, dry conditions can be stored for long periods, but as seed moisture or temperature rises, storage length becomes less. The drier and cooler the grain, the safer it is during storage.
  • Extra care should be taken to monitor the grain inside the bin for moisture build-up or spoilage, temperature, and for the presence of insects.
  • It’s important to be cautious of weed seed dockage or green materials (i.e. Canada thistle heads) from volunteer crops, as they can cause heating (hot spots) if you cannot not get proper air flow through the bin.
  • Bins should be temperature monitored to ensure no heating occurs. A variety of manual and automated systems are available to help keep track of seed condition.
  • If pulses require handling, they should be moved as little as possible, and handled gently to avoid cracking and damaging the seeds. Use belt conveyors instead of augers. If using augers, run the auger full and at a reduce speeds. Use ladders on equipment to minimize the dropping of seed from more than a few feet.
  • Pulses, in general, should not be cleaned or handled below –20˚C because of the increased risk of chipping and peeling.
  • See PAMI research for more information:  Improved Management of Stored Pulses, Research Update, August 2019, PAMI


  • Soybeans can be dried using any drying method.
  • If using a grain dryer, care must be taken to avoid over-drying the soybeans to prevent excess shrinkage.
  • Dried grain needs to be cooled down using fans or aeration after drying.
  • If drying soybeans using natural air in an aeration system, it is best done with a full aeration floor to ensure even movement of air and drying.
  • Using air for temperature control is known as aeration while using ambient air for drying is know as natural air drying (NAD).
  • Blowing air through grain is the most common method to control temperature in the bin. If the grain is tough but not wet, then blowing ambient air through the grain can also result in moisture removal.
  • When drying soybean, the time to run your fans will depend on airflow rate, starting moisture content, and ambient conditions.
  • Run the fans when the average ambient temperature is cooler than the grain.
  • Latest research:  PAMI – Improved Management of Stores Pulses, Research Update, August 2019
  • If the seed moisture content must be reduced by 5% or more, drying should take place in two stages.
    • With a hot air dryer, soybeans should be dried to within 2% of final moisture content and then tempered in an aeration bin for at least 6 hours.
    • Afterwards, they should be cooled to the outdoor seasonal temperature. The slowness of this process prevents grain cracking.


Grading standards are determined by the Canadian Grain Commission. Through the harvest sample program, farmers have the opportunity to send in harvested samples to the Grain Commission for grading. This grade can be compared with local buyer grades and may assist in marketing

Source: Canadian Grain Commission, Soybean Grading Factors

See Soybean:  Primary and Export Grade Determinants Tables



  • Soybeans may be yellow, green, brown, black or mixed. Colour is part of the grade name; for example, “Soybeans, No. 1 Canada Yellow”.
  • The method for determining the colour of a soybean is by seed coat colour.

Grade names –

Soybeans, Canada Yellow, Green, Brown, Black or Mixed

  • No. 1 Canada
  • No. 2 Canada
  • No. 3 Canada
  • No. 4 Canada
  • No. 5 Canada
  • Grade, if No. 5 specifications are not met.
  • Reasons for downgrade include:
    • weight is assessed as standard of quality
    • degree of soundness includes temperature, natural odour and lack of staining
    • damage (heat-damaged or mouldy, total %)
    • downy mildew %
    • other colours or bicoloured other than for mixed soybeans%
    • foreign material (ergot, excreta, insect parts, stones, foreign material other than grain, and total %); and
    • splits.


Dockage is any material intermixed with the grain, other than the grain, that must and can be separated from the parcel of grain before a grade can be assigned. 

  • Dockage is assessed only on unprocessed samples (referred to as the uncleaned or dirty sample) and is assessed on the gross weight of the sample.
  • Dockage is removed by cleaning procedures and then assessed and recorded to the nearest 0.1%.
  • Dockage is not reported for samples grading
    • “Soybeans, Sample Canada (colour) Account Fireburnt”
    • “Soybeans, Sample Salvage”
    • “Soybeans, Sample Condemned”
  • Procedures for the determination of Soybean dockage can be found at Canadian Grain Commission, Soybean:  Determination of Dockage.


  • Test weight is the weight of a measured volume of grain expressed in kilograms per hectolitre. For procedures, see Determining Test Weight, Chapter 1 of the Official Grain Grading Guide.


  • Staining or mottling on the surface is caused by weather, dirt, weed stain, or disease. If the soybeans are not damaged or discoloured internally, they are considered sound.
    • Good natural colour – Grade No. 1
    • Slightly stained – Grade No. 2.
    • Stained – Grade No. 3.
    • Badly stained – Grade No. 4 or 5.
  • Pokeweed stain is a bright red staining of the soybean seed coat caused by the sap of the pokeweed berry. In some cases, the staining may appear similar to pesticide treated seeds of soybeans.


  • Colour is evaluated on the cleaned sample after the removal of damaged seeds.
  • Colour is assessed against the standard of quality by using the applicable standard prints published for the grade.
  • Yellow soybeans with green coloured hulls, but are not immature, shall be graded no lower than “Soybeans, No. 2 Canada Yellow”.
  • Soybeans in various stages of rancidity are characterized by a deep pink discolouration on the seed coat and varying degrees of discolouration of the cotyledon. Those with no discolouration of the cotyledon to slight discolouration just below seed coat are considered in the evaluation of colour.


  • Odour: There is no numeric tolerance for odour.  Consider the basic quality of the sample; the type and degree of the odour, and the presence of visible residue causing the odour. If odour is the grade determinant and there is:
    • If there is a distinct unnatural or objectionable odour not associated with the quality of the grain, but not heated or fireburnt– then the grade is “Soybean, Sample Canada (colour) Account Odour”.
    • A heated odour:  Soybeans will a heated odour will be graded as “Soybean, Sample Canada (colour) Account Heated”.  For those soybeans that are considered to be rancid, pink discolouration extending throughout the cotyledon are considered rancid and included in the tolerance for heated.
    • A fireburnt odour: Soybeans with a fireburnt odour will be graded as “Soybean, Sample Canada (colour) Account Fireburnt”.


  • Splits include split soybeans, broken seeds that are less than ¾’s of the whole seed, and cotyledons that are loosely held together by the seed coat.
  • In unprocessed samples, loose seed coats are assessed as dockage.
  • In commercially clean samples, loose seeds coats are assessed as splits.


  • Damaged soybeans are those which are sprouted, frost-damaged, shriveled, ground-damaged, insect damaged, immature, or otherwise unsound.
  • Sprouted is a soybean which shows evidence of sprouting and is considered damaged.
  • Frost-damaged: When cut in cross-section, soybeans are considered frost-damaged when cotyledons are green or greenish-brown with a glassy wax-like appearance. Seeds whose cotyledon are yellow or have just a halo of green around the outside of the cotyledon are considered sound, even if they are superficially affected by weathering.
  • Fireburnt soybeans are seeds charred or scorched by fire. A cross-section of a fireburnt seed resembles charcoal with numerous air holes. The air holes result in a low weight seed which crumbles easily under pressure.
  • Heated are soybeans with a light to dark brown cotyledon when cut in cross section are considered heated. Soybeans with a very light tan cotyledon when cut in cross section are considered damaged. Heated seeds of other grains are included in the tolerance for Heated. 
  • Rancid soybeans with pink discolouration of cotyledon greater than just below the seed coat level but not throughout the entire seed are considered as damaged.
  • Immature damaged soybeans are characterized by a green exterior appearance in conjunction with green discolouration penetrating the cotyledon. Soybeans that are green in appearance and have no discolouration of the cotyledon or just a halo of green around the outside of the cotyledon are to be assessed against the overall colour of the sample and are not to be graded lower than “Soybeans, No. 2 Canada Yellow”.
  • Insect damaged soybean kernels are characterized by a perforation of the seed coat in conjunction with a discoloration penetrating in the cotyledon.
  • Shrivelled are distinctly distorted and shrunken, or have a severely dimpled surface.


  • Downy mildew is a superficial coating of downy or powdery fungal growth. An individual soybean is considered affected only if all of the fungal growth could be pulled together and the growth covers 50% or more of the surface area of the soybean.


  • Foreign material includes any material other than whole soybeans or split soybeans left in the sample after the removal of dockage.
    • Hard earth pellets are pellets or stones that do not crumble under light pressure.
    • Ergot is a plant disease producing elongated fungal bodies with purplish-black exterior, a purplish-white to off-white interior, and a relatively smooth surface texture.
    • Excreta is excrement from any animal including mammals, birds, and insects.
    • Insect parts refer to pieces of insects such as grasshoppers and lady bugs that remain in the sample after cleaning or processing. 
    • Stones are hard shale, coal, hard earth pellets, and other non-toxic materials of similar consistency.
    • Fertilizer pellets are a manufactured plant nutrient product used by producers in the production of grain. They are typically small, round or irregular shaped and usually white, grey, brown, pink or reddish in colour.
    • Fertilizer pellets are assessed as stones when constituting 1.0% or less of the net sample weight.
  • Foreign material other than grain does not include ergot or stones, but does include:  large weed seeds that did not pass through the No. 8 round-hole sieve; soft earth pellets which crumble under light pressure; soft fertilizer pellets; any other non-toxic material of a similar consistency; and Sclerotinia.
    • Soft earth pellets are pellets that crumble under light pressure. These pellets can be earth and fertilizer pellets, or any non-toxic material of similar consistency.
    • Sclerotinia sclerotiorum is a fungus producing hard masses of fungal tissue, called sclerotia. The sclerotia vary in size and shape, have a coarse surface texture, vary in exterior color from dark black to grey to white and have a pure white interior.


  • Contaminated is defined in the Canada Grain Act as; “Contaminated means, in respect of grain, containing any substance in sufficient quantity that the grain is unfit for consumption by persons or animals or is adulterated within the meaning of the regulations made pursuant to sections B.01.046(1), B.15.001 and B.15.002(1) of the Food and Drugs Act.”
  • Samples deemed to be contaminated by the Grain Research Laboratory in consultation with the Chief Grain Inspector for Canada are graded “Soybeans, Sample Condemned”.
  • Fertilizer pellets in excess of 1.0% of the net sample weight are graded Soybeans, Held IP Suspect Contaminated Grain.
  • If a sample is suspected of being coated with a pesticide, desiccant, inoculant or if the sample contains evidence of any foreign chemical substance other than fertilizer pellets, the sample shall be graded “Soybeans, Held IP Suspect Contaminated Grain”.


  • Treated seed is grain that has been coated with an agricultural chemical for agronomic purposes.
  • These seed dressings contain a dye to render the treated seed visually conspicuous.
  • The colour of the dye varies depending upon the type of treatment and the type of grain.
  • Seed treated with an inoculant may have a green stain.
  • The coatings or stains may appear greasy or powdery and surface area distribution ranges from tiny flecks to complete coverage.


  • Earth-tagged seed has dirt attached that cannot be removed. Earth tag may occur during combining when moisture from weeds or heavy dew causes soil or dust to stick to the seed.
  • To reduce earth tag in soybean, follow these management tips:
    • Select a soybean variety with a good harvest rating.
    • Roll your soybean prior to emergence, to eliminate ridges and an uneven seed bed. This approach will minimize dirt entering the combine (normal plant dust will not adhere to a dry soybean seed coat, but combined soil will).
    • Use an approved herbicide at the proper desiccation stage to even out crop drydown and eliminate green weed material. Green material is either green weeds or green soybean plant material that will increase the level of earth tag on the seed.
    • Ideal moisture content for soybean storage and harvest is 13%, however, harvesting can begin at 20%. Soybean combined at 20% moisture will require aeration conditioning for short-term storage. Below 13% is undesirable due to shatter loss, splits, and weight loss.