Active‐Optical Reflectance Sensing Corn Algorithms Evaluated over the United States Midwest Corn Belt

Core Ideas Active‐optical reflectance sensor algorithms perform poorly outside the area for which they were originally developed. The red edge waveband is more sensitive to N stress than the red waveband. Some active‐optical reflectance algorithms are dependent on the sensor for which they were developed. Uncertainty exists with corn ( Zea mays L.) N management due to year‐to‐year variation in crop N need, soil N supply, and N loss from...