||This report summarizes a workshop in which the APSIM (Agricultural Production Systems Simulator) farming systems model was applied to the analysis of management options critical to maize production in Zimbabwe. The modeling analysis focused on responses to investment in nitrogen fertilizer inputs, in terms of investments in timely sowing and weeding. The study evaluated a number of alternative scenarios of land, labor, and financial constraints for a farm household which were based on local information. Scenarios were established whereby the resources available could be deployed in different ways over multiple fields on the farm. In one scenario, fertilizer inputs, and weeding and plowing/sowing efforts were concentrated on a portion of the farm and the remainder was left idle. In another scenario, the resources were spread evenly over the whole farm; others involved the shifting of resources between investments in fertilizer inputs, early sowing, and more effective weeding regimes. The study was configured for a farm in Natural Region II using a Harare climate data on a shallow, infertile, sandy soil. Since the farm household constraints were very simply defined, the study needs to be repeated with more careful specification of the constraints and in other drier regions of the country. Despite these deficiencies, the study does highlight the challenges that smallholders face when investing in fertilizer inputs, and provides some direction for future on-farm research.