There is a large body of research on characterizing field variability of soil characteristics and their impact on crop yields. In contrast, site-specific information about crop responses to agronomic treatments is less frequent. On-farm precision experimentation (OFPE) brings important information to understand the spatial variation of crop response to agronomic practices and thus to improve agronomic decisions. The objective of this work was to investigate the spatial variability of corn yield responses to nitrogen and seed rates using OFPE in four fields in the US Midwest. Geographically-weighted regression was applied to generate local regression coefficients, which were used to delineate response zones in each field. The results showed the existence of great potential to adjust the rates of these inputs according to the response of each zone identified by the proposed method. The results of this study can be applied to re-evaluate expectations on variable rate prescriptions guided largely by soil and variability.