Scheduling contractors' farm-to-farm crop harvesting operations

The harvesting of renewable resources from an operations scheduling viewpoint is introduced, and a harvesting scenario arising in the agricultural context involving a commercial contracting enterprise that travels from farm-to-farm harvesting crops is discussed. This paper is an extension of previous work by two of the authors from the one-farm to the multi-farm case. In both cases, the duration of each operation is dependent upon the combination of constrained resources allocated to it, equipment and worker allocation is restricted, and minimum or maximum time lags on the start and completion of operations may be imposed. The present case incorporates harvesting at more than one farm and thus the sequence in which the farms are visited and the inter-farm travel times must be taken into account. We report on a harvesting scheduling model and solution procedures designed specifically for large-scale versions of the multi-farm case. The computational times experienced in solving general instances of the model of small-to-medium practical size by a commercial integer programming package are encouraging. Greedy and tabu search heuristics, which are capable of solving problems of relatively large dimensions in reasonable computational time are also included. The authors believe that the model and the solution techniques developed represent a useful addition to the farm crop contractor's tool kit.