I disagree, Certification has helped my bottom line dramaticlly in Direct sales. I am als Certified Naturally Grown. That Organization costs zero, but asks for donations if you can help. It is designed for the Family farm and small Farm operations and may fit your need. They follow the same NOP Rules. The USDA Certification helps open other doors and venues and people will seek you out if you are Certified Organic.
You should contact youe Certification agency with any questions dealing with issues of seed, fertilizers, and even OMRI Approved chemicals to be on the safe side. I call mine all the time just to make sure before I use anything!
They will talk to you even if you are not certified. Most are very knowledgable and friendly, but if you run across a stinker, try again with a different person or group, after all , we are still all humans ...