In sampling commercial fertilizers packed in packages of twenty-five (25) pounds or less, an original unbroken package may be taken as the official sample and the ordinary retail price tendered therefor. When the fertilizer is in packages of over twenty-five (25) pounds in weight, portions for the official sample shall be taken from at least ten packages, if there be that many in the lot. In sampling fertilizers in bulk, not less than ten portions shall be drawn, and these from various parts, so as to represent fairly the whole. The owner of the fertilizer or a representative of the owner may be present, but any refusal by such owner or representative to permit sampling shall be taken as sufficient evidence of violation of the law by him or her.