Oats: Determination of dockage


Dockage is assessed to the nearest 0.1%.

Dockage is defined under the Canada Grain Act as “any material intermixed with a parcel of grain, other than kernels of grain of a standard of quality fixed by or under this Act for a grade of that grain, that must and can be separated from the parcel of grain before that grade can be assigned to the grain”. Dockage is removed by following the cleaning procedures described in this chapter.

The sample as it arrives is referred to as the uncleaned or dirty sample. Its weight is the gross weight of the sample. Dockage is assessed on the gross weight of the sample.

Dockage is assessed in two stages.

  1. Follow Normal cleaning procedures, using the Carter dockage tester.
  2. Follow procedures for Cleaning for grade improvement. This cleaning can be done at any time after the cleaning assessment has been completed.

Dockage not reported

Important: Dockage is not reported for samples graded

  • Oats, Sample Canada Western (CW)/Canada Eastern (CE), Account Fireburnt
  • Oats, Sample Salvage
  • Oats, Sample Condemned

Normal cleaning procedures

Important: Wear gloves and a mask to handle any samples that you suspect may contain hazaradous substances.

  1. Set up the Carter dockage tester as follows:
    Specifications for Carter dockage tester
    Feed control # 5
    Air control # 3
    Riddle number 6
    Top sieve number 6 buckwheat
    Centre sieve number 5 buckwheat
    Bottom sieve Blank tray
    Sieve cleaner control Off
  2. Using a Boerner-type divider, divide the uncleaned sample to obtain a representative portion.
    • Official samples shall be at least 1 kg.
    • Unofficial samples shall be at least 1 kg.
  3. Turn on the Carter dockage tester.
  4. Pour the sample into the hopper.
  5. After the sample has passed through the machine, turn on the sieve cleaner control for 2 to 3 seconds to remove kernels lodged in the sieve.
  6. Turn off the dockage tester.
  7. Lightly snap the retainer rod of the aspiration pan to loosen material gathered on the air screen.

    Important: These are the normal settings. Ensure when you are aspirating lightweight oats that fully developed, sound oats are not removed from the sample.

    If the aspirated material contains whole, sound oats:
    1. Return the material to the sample.
    2. Reset the dockage tester with a lower air setting to remove only lightweight dockage material.
    3. Pass it through the Carter dockage tester again.
  8. Remove the aspiration pan.
  9. Determine dockage, using the list under Composition of dockage.

Composition of dockage

Dockage includes

  • Material removed over the number 6 riddle
  • Lightweight material removed by aspiration
  • Material that is removed by the number 5 buckwheat sieve
  • Soft earth pellets, up to a maximum of 10% of the gross weight of the sample, handpicked from the clean sample
  • Material removed by Cleaning for grade improvement

Cleaning for grade improvement

If the grade of a sample can be improved by additional cleaning, perform the cleaning and add the additional material to dockage. Cleaning for grade improvement can be done any time after the cleaning assessment has been completed, including on export.

  1. After the cleaning assessment has been completed, examine the material to be removed and select your equipment according to the material you want to remove. See the table Cleaning for grade improvement–Oats for the list of equipment.
  2. Sieve the sample by hand, or pass it through the Carter dockage tester, depending on the material.

    Important: When you use a hand sieve, move the sieve from left to right 30 times, using a sifting motion. One time is one complete motion from the centre, to one side, to the other side, and back to the centre. The total distance from left to right is 20 cm, or about 8 inches.

  3. Weigh the additional dockage and add it to the original dockage.
Cleaning for grade improvement—Oats
Material to be removed Equipment Effect on composition of dockage
Large seeds number 6 buckwheat hand sieve Large seeds are
  • Seeds that do not pass through the number 4.5 round-hole sieve
  • Grains other than cereal grains, such as peas, beans, corn, flaxseed and domestic buckwheat
  • Ragweed and Tartary buckwheat

Assess material as dockage, provided the grade is improved and not more than 5.0% of oats are removed.

Covered smut and false loose smut

Carter dockage tester, set up for Normal cleaning procedures, but with air control set to 7

Note: The material originally removed by aspiration is to be reconstituted back into the sample prior to cleaning for improvement.

If the percentage by weight of material removed is
  • Less than 2.0% of the gross weight of the sample, add to dockage
  • 2.0% or more of the gross weight of the sample, the sample is sent to the Chief Grain Inspector for review.

Optional analysis

Where a shipper requests special cleaning of a carlot of grain at a terminal elevator, and the elevator manager agrees, dockage material will be analyzed for the presence of grain. The percentage and grade of any grain contained in the dockage will be reported.


  1. Analyze the official sample.
  2. Record the following on inspection records:
    • The percentage by gross weight to the nearest 0.1% and the grade of oats.
    • The percentage by gross weight to the nearest 0.1% and the grade of grain separable from dockage.
    • The percentage of dockage.


    • 95.0% Oats, number 1 Canada Western
    • 4.0% Domestic Mustard Seed, number 1 Canada Oriental
    • 1.0% dockage
Date modified: