Sampling and Subsampling - Seed Testing - page 33

to be uniform enough to allow representative sampling. Figure 3.2 shows three different ways by which
seed is sampled.
Bulk Seed. A partitioned or compartmentalized trier, or probe, is recommended under most situations,
although hand sampling may also be performed if several handsful are taken from well-distributed points
throughout the bulk. Large probes (triers) up to seventy-two inches in length can be used to sample hard-to-
reach locations within the seed lot. Pneumatic systems are available for sampling from large bulks of seed,
however, these should be used with caution to avoid bias in the submitted sample. Since they might tend
to select lighter chaff and inert matter or other crop and weed seeds having lower specii c gravity and less
resistance to airl ow than the pure seed, they have the potential to produce a sample that is not representa-
tive of the seed lot.
Seed in Bags. The AOSA rules specify that when a seed lot consists of six bags or less, each bag
should be sampled from at least i ve well-distributed points throughout the bag. When lots consist of more
than six bags, samples should be taken from i ve bags plus 10% of the remaining bags. Regardless of the lot
size, however, it is not necessary to sample from more than thirty bags. Here are some examples:

No. of bags in lot 5 7 10 23 50 100 200 300 400

No. of bags to sample 5 6 6 7 10 15 25 30 30

After the decision regarding the number of bags or containers to be sampled is made, the procedure by
which the actual bags are to be sampled should be determined. Usually this will involve a certain percent-
age of all bags in the lot and involve every 5 th , 6 th , 7 th , or 10 th bag or so to meet the AOSA specii cations,
depending on the number of bags in the lot.
Seed in Small Containers. Seed in small containers should be sampled by taking at random an entire
unopened container from the supply in order to obtain the minimum amount required for the working
sample. For sampling from mini-bulk containers, refer to the AASCO sampling handbook.

Figure 3.2. Seed sampling methods: (A) bag sampling; (B) bulk sampling; and (C) mechanical sampling
(from Copeland and McDonald, 2001).