Corn and soybeans are the two primary row-crops grown in Iowa. In 1993, 11 million acres of corn was planted, with an average yield of 149 bu/ ac. In the same year, 8.1 million acres of soybean was planted, with an average yield of 44 bu/ ac (Iowa Crop Report, 1994). Growers are under increasing pressure to produce crops with minimum effects to the environment. This must be done without compromising the economic sustainability of the farm. It is becoming more difficult to determine the optimum crop production strategy because the system constraints continue to increase. In the future, farmers will rely more heavily upon the use of computers to aid in decision making to determine the optimum crop production strategy including variety selection, planting date, irrigation, pesticide applications, fertilizer strategies, and manure applications.