Use of state or county appropriations

The funds appropriated for the purposes of sections 4:16-22 to 4:16-30 of this title by the state and the counties shall be used only, except for the payment of salaries and expenses as provided in said sections 4:16-22 to 4:16-30, in giving field instruction on their own land to farmers selected by the director of the extension service, as a part of the regular business of farming; and no part of such appropriations shall be used in maintaining a state farm, in conducting experiments not in the line of regular farm work, or in the distribution of literature.