If requested by the deliverer of grain or oilseed on which a discount or weight deduction is assessed, one-half must be placed and sealed in a tamper-proof container provided by the Department of Agriculture and the container must be returned to the deliverer of the grain or oilseed sampled, tested or graded. Records shall be maintained for a period of one year on each lot of grain or oilseed for which a grade is determined by the dealer and handler in order to assist the Commissioner in evaluation grading performance. The Commissioner may suspend or revoke a grader’s certificate when he deems the grader incapable of competent performance.