Corn: Determination of dockage

Definitions

In eastern Canada the terms of delivery or terms of a contract will determine if dockage is to be assessed. In western Canada dockage may only be assessed on tough, damp, moist or wet corn. The Canadian Grain Commission will only assess dockage upon request. Dockage is assessed and recorded to the nearest 0.1%. Once dockage material has been removed it will not be reintroduced to the sample to determine the grade.

Cracked corn and foreign material (CCFM) is a grading factor and will be assessed when determining the grade.

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 procedure 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 not reported

Normal cleaning procedure

Assess dockage before assessing test weight.

Procedures for normal cleaning of corn require

• numberNo. 12 round-hole hand sieve for corn with 25% moisture or less
• numberNo. 14 round-hole hand sieve for corn over 25% moisture

1. 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.
2. Sieve approximately 250 g at a time on the appropriate hand sieve until all possible material has fallen through the sieve.
3. Handpick material remaining on top of the sieve as described under composition of dockage.

Composition of dockage

• All material which passes through the numberNo. 12 or numberNo. 14 round-hole sieve
• All foreign material and pieces of cob handpicked from the sample, excluding stones (STNS)