The efficiency with which applied resources are utilized in sub-Saharan African cropping systems is especially critical as the resources are generally scarce. Research efforts to improve farm productivity increasingly focus on resource interactions and trade-offs operating at farm-scale. Farm-scale models that integrate summary models of the various subsystems (crops, livestock, household) are proposed to analyse the complexity of management systems. NUANCES-FIELD is a summary model of the crop/soil system that calculates seasonal crop production based on resource availability, capture and utilization efficiencies. A detailed mechanistic crop growth model, APSIM, was used to generate parameters and variables that can be introduced as descriptive functions in NUANCES-FIELD. To such end, we first parameterized and tested APSIM based on several field experiments carried out on different soil types in western Kenya farms where nitrogen and/or phosphorus were applied. The model was further configured to generate nitrogen and phosphorus response curves as a function of soil condition (carbon content, clay content, phosphorus-sorption characteristics) and the effects of alternative weed management scenarios in relation to labour availability. Nitrogen, phosphorus and rainfall capture efficiencies ranged between 0.22- 0.85 kg kg_1, 0.05-0.29 kg kg_1 and 0.10-0.53 mm mm_1, respectively, depending on soil nutrient and physical conditions. Variation in the integrated seasonal fraction of radiation intercepted (intFRINT) with plant density was adequately described by the function y = 0.058x + 0.11 within a range of 1.5-5.5 maize plants per m2. Investigation of weed management using the APSIM model identified a weed-free period of at least five weeks from maize emergence for minimum yield loss from weed-crop competition. The simulation exercises confirmed that resource-use efficiencies sharply decrease on moving from relatively fertile fields 'close' to the homestead towards deg