The objectives of this study were to: (1) quantify the factors causing spatial variability, and (2) design a proof of a concept for a support system that considers the impacts of temporal variability. The subdivision of a field based on six years of spatial yield data identified areas with different levels of stable and unstable zones. Overall, in the 0.0-0.30 m, the soil had between 40 to 60% across all the zones, while at depth, the clay content was about 20% and sand content 30 to 40%. The growing season rainfall for the period 1983-2018 was highly variable, ranging from 152 to 570 mm. The support system showed that there was a general trend where higher growing season rainfall (e.g. 566 mm) corresponded to higher yields, but this meant lower soil nitrogen content at harvest. However, the nitrogen leaching was not always lower and ranged between 20 to 70 kg N/ha. Results of this study will enable the development of an agronomic site-specific N management that would maximize the farm's net income and minimize the environmental footprint.