Section 84. The county commissioners of any county may purchase or lease land, with funds specifically appropriated therefor by the general court, for the purpose of improving and cultivating the land by the labor of prisoners from a jail or house of correction; and the said commissioners may also make arrangements with the department of highways or with the officials of a town to employ said prisoners on any highway or unimproved land, or with the director of the division of forests and parks in the department of environmental management for the reforestation, maintenance or development of state forests, or with a private owner to improve waste or unused land, or land used for agricultural or domestic purposes, by means of such prison labor. When prisoners are so employed they shall be in the custody of the sheriff of the county. When land that is not the property of the county or is a public way or state forest is so improved, the owners thereof or those having the way or forest in charge shall pay the county such sums as may be agreed upon between the county commissioners, sheriff, and the other parties in interest for the labor of any prisoners employed thereon.