Land requirements for seed certification are as established in the specific seed crop standards. When a cultural practice has proved to be successful, requirements may be modified upon written approval of the seed certifying agency. Cultural practice may include any of the following:
(1) Mechanical means such as deep plowing.
(2) Chemical means such as fumigants.
(3) Other material for seed bed preparation. Materials and methods must be a matter of record. Any practice used must be adequate to ensure varietal purity and must be approved in writing by the certifying agency. Any deviations from established land requirements must be submitted in writing to the certifying agency.