CORNDRY is a deterministic model simulating a corn growth, harvesting, bin filling, and drying system. It was developed by modifying and combining the CORNSIM and FALDRY models which were previously developed at Iowa State University;The merit of CORNDRY model is that it can control the time of harvest in simulation by judging the field working condition, the system drying capacity, the corn moisture in the field and other preset conditions. It becomes more powerful when an optimum controlled-filling strategy is applied;Another model, FLDAY, was also developed to generate the appropriate field working data required for the CORNDRY model. In this study, the FLDAY model has been verified with observed data and was found to have a very good correlation;The CORNDRY model was used for a management study for northwestern Iowa using twenty years of weather records for Sioux Falls, South Dakota, to simulate a corn production system of a 300-acre medium-size farm in the same area;Two management schemes of field arrangements for these 300 acres were used: one planted half with medium and half with short season corn, the other planted all with short season corn. Two fan power levels--8.8 kW and 13.2 kW were also considered for a drying system of four bins with capacities of 10,000 bushels for each bin. All drying was done using a controlled filling strategy;For the first scheme in northwestern Iowa, predictions show that the harvested corn can be dried completely in fall for fourteen out of twenty years if an 8.8-kW fan is used and for sixteen out of twenty years if a high powered fan (13.2 kW) is considered. For the latter case, the fan operation time decreases from 1,160 hours to 830 hours. The second scheme tends to decrease the number of spring finishes to six for the 8.8 kW fan and to four for the 13.2 kW fan. The grain quality is good (dry-matter loss < 0.1%) when drying is completed even when spring finishes are required.