The Free State Midlands is a high-risk area where summer and winter crops are cultivated under various rotational and fallow systems. Six such systems in general use were identified and with the aid of crop growth simulation models and weather input data long-term yield data were generated. The economic results of the various systems were evaluated for a period of 24 years (1960 to 1983) for a hypothetical farming unit of 600 ha. The various systems were evaluated in respect of gross farm production value, margin above variable costs, net farm income and farm profit, based on the average yields for the period at 1983 prices. The annual farm profit figures, purchasing power and financial risk were also evaluated. It appears that the protracted wheat fallow system is the most economic of the six. It is also clear that the financing risk can be reduced for both the farmer and the financial institution by coupling the granting of loans to the physio-biological aspects of a farming unit. Furthermore, recommendations of crop choices based mainly on gross margins are laden with potential dangers.