Optimization of runoff agriculture on reclaimed mine lands

Abstract

Optimization of runoff agriculture involves the selection of a crop whose water requirements correspond to the precipitation patterns of the area; the selection of a runoff treatment which, when applied to the catchment area, produces the greatest amount of water at the lowest cost; and the establishment of the ratio of catchment area to crop area. A model is presented which utilizes linear programming and watershed cropland simulation to select the best suited crop and runoff treatment for the system being considered. The model is then modified to determine the optimum catchment area ratio to be used. The model was applied to the reclaimed coal mine lands on the Black Mesa of northern Arizona. Results show that maximum economic returns can be obtained for conventional irrigated agriculture by using a ratio of 55 acres of catchment area with no runoff treatment to one acre of cropland producing corn. The use of carry-over pond storage to allow for supplemental irrigation is prohibited due to high evaporation rates on the Black Mesa. By reducing the corn crop density from the conventional 20,000 plants per acre to 5,000 plants per acre, the catchment area ratio can be reduced to an apparent ratio of 13:1. Hopi Indian farmers on the Black Mesa use a density of 5,000 plants per acre for cultivating a highly adapted strain of Indian corn.