Where there is organized in a county a soil conservation association, whose membership shall comprise bona fide landowners, incorporated under the Cooperative Marketing Law, compiled in chapter 16 of this title; and when sufficient members of the association have agreed with the association by written contract to pay their proportionate share of the cost of terracing, including operating cost and retirement of the original purchase price of the terracing equipment, a minimum total of five thousand (5,000) acres; and when the authorizing officers of the association have petitioned the county legislative body with proper evidence that bona fide landowners in the county desire to have a minimum of five thousand (5,000) acres terraced and pay their proportionate share of the cost of constructing the terraces, including the retirement of the original purchase price of the terracing equipment, the county legislative body is authorized within its own discretion to make an appropriation for the purchase of terracing equipment for use on farm lands in the county, and on farms of the members of the association, and the county legislative body shall be reimbursed for the original cost of the equipment through the payment by each member of the association of that member's proportionate share of the cost of the equipment, including operating cost for each acre of land terraced.