Purity testing has been established to ensure the seed lot is clean. In fact purity is the first step in seed quality.
In this video, the seed analyst takes a thoroughly mixed sample of a known quantity according to the rules for the country of origin.
The seed analyst pours the seed — in this case creeping red fescue — on to a clean glass purity slab and searches through the seed. We are interested in weeds, other crops and inert matter to establish the purity of the sample.
The contaminants are separated and weighed. Once the sample is complete it is placed back into the seed envelope for further testing and sample archiving.