Abstract A Decision Support System (DSS) was developed for optimization of farm machinery systems with the flexibility to incorporate regional variations in crops and cropping practices, farm characteristics, sizes of farm equipment, and costs of the resources and outputs. Two sources of mobile power, animals or tractors, and two sources of stationary power, electric motors and diesel engines, were considered. The DSS presents the optimum power solution for mobile and stationary operations, and selects the optimum power sources and the matching equipment from those available in the region. It gives working hours required; energy used; fixed, operating and timeliness costs for each of the selected farm operations; and economic returns on area, crop, seasonal and annual bases. To demonstrate the utility of the DSS, a simple, realistic but hypothetical case study was made. Analysis of the system outputs of the DSS was carried out for this case. Net returns per hectare of the crop area for all possible combinations of power sources were compared to determine the optimum system of farm machinery.