In order to promote agricultural interests of the various townships of this state and to provide for agricultural extension work for such townships, each township of this state through its township board is hereby authorized and empowered to cooperate to said end with the Michigan state university of agriculture and applied science; and may enter into agreements with reference thereto. The township board in any county may appropriate money, or raise money by taxation, for the purpose hereof. Two or more township boards may act jointly; and a township board may describe an extension area within any township and may levy a special tax from said area to carry out the provisions of this act.