Upon the written request of a majority of the board of commissioners, the department of corrections may detail such able bodied convicts as in its discretion shall seem proper, not exceeding the number specified in the written request, to work upon public projects of a county. The county shall pay to the general fund a certain fixed amount of money per day for each man so detailed, which amount shall be decided upon by the corrections commission. The amount to be paid shall be a fair and just compensation for such labor. The county shall pay expenses of transportation to and from the county and shall provide or pay for the lodging and food of the convicts while employed by it and shall furnish all tools and materials necessary in the performance of the work. The convicts employed upon the public projects shall be under the care and custody of officers as the department of corrections shall designate, and the expense of guarding if guards are necessary shall be borne by the county. Where 2 or more applications shall be on file they shall be filled pro rata. All moneys collected under the provisions of this section shall be turned over to the state treasurer and credited to the general fund.