Technical Abstract: Reducing N loss from agricultural lands and applying N fertilizer at rates that satisfy both economic and environmental objectives is critical for sustainable agricultural management. This study investigated spatial variability in maize yield response to N and its controlling factors along a typical agricultural hillslope in the Northern Appalachian Ridge and Valley Physiographic Province in the USA. Spatial variation of soil, topography and soil moisture along the hillslope were determined through electromagnetic induction surveys, digital elevation model, and soil moisture monitoring. Minimum, maximum, and delta yields and optimum N rate at different slope positions were determined using quadratic-plateau maize yield - N rate models. Results from 2008 and 2009 indicate that spatial variability of maize yield response to N was influenced by silt content (represented by EM31H survey), soil depth (represented by EM31V survey), profile curvature, slope percent, soil wetness and soil moisture temporal stability. In both drier and wetter years, optimum N rates increased with temporal variation of soil moisture, which is an indicator of soil water contributions from subsurface flow paths. In the drier year of 2008, maize yield was little varied along this hillslope (11.7-12.0 Mg ha-1), while greater yield response to N (represented as delta yield) was observed in upper convex and steep slope areas with low minimum yield. However, in the wetter year of 2009, greater maize yield and yield response to N were observed in lower concave slope areas with deeper soil depth and thus greater water storage. Results from this study illustrate that site-specific N fertilizer applications could be improved by incorporating within field variability of soil, topography and hydrology with the yearly variation of weather condition.