Does a chemical lawn-care company qualify as an agricultural business? (denied overtime pay)

I am currently work at a business in Michigan that sells lawncare including fertilizer, chemical weed control, tree spraying, and occasionally lawn seedings.

The owner claims they are an agricultural business because most of their yearly revenue is from spreading fertilizer. Because of this, he claims he doesn't have to pay us overtime. Does spreading fertilizer alone qualify you as an agricultural business? Note that we do NOT spread fertilizer for anything besides other people's lawns and ornamental trees and shrubs.

Considering the guy works us 70+ hours a week since April, there is a lot of potential overtime pay for 5 or 6 people.

Bonus Question:

Is there anything we should know before reporting this same company for EPA and DoA violations relating to chemical storage and disposal and the like? We figure at the least we owe the world a few anonymous letters to those agencies but I myself would like to do more than that.