Over the past decade, the relationships between leaf color, chlorophyll content, nitrogen supply, biomass and grain yield of agronomic crops have been studied widely. In many parts of the world, nitrogen fertilization and artificial water supply are major inputs required to achieve relatively high yields. However, as a result of the increasing costs of energy and a decline in available water, researchers are looking for ways to increase fertilizer and water use efficiency. Site-specific management of these inputs is a promising approach that involved the use of real-time crop canopy sensors. Since the effect of nitrogen and water stress can produce similar changes in optical sensor measurements, the goal of this work was to integrate conceptually different sensing elements to evaluate crop canopy performance during the growing season. Thus, active optical crop canopy sensors have been augmented with ultrasonic proximity and infrared thermal sensors to simultaneously assess crop canopy chlorophyll content, height and biomass, as well as temperature. Integrated sensors have been used to study the interactions between water stress and nitrogen stress in corn.