The county legislative bodies are empowered to appropriate annually such an amount of money as may be deemed necessary or expedient in order to cooperate with the division of extension of the college of agricultural sciences and natural resources of the University of Tennessee, in its farm demonstration and agricultural extension work, to be conducted by such college in cooperation with the United States department of agriculture through the Smith-Lever bill (7 U.S.C. § 341 et seq.), the farmer's demonstration work, or other work supported by acts of congress, or in its extension work to be conducted through appropriations from the state, or through moneys received from any other source.