New technologies for monitoring crop growth and development have been developed and new variable rate soybean management techniques are available, but there is little soybean research information to guide the use of such techniques. In Kentucky, soybean growth is stressed by too little water, too much water, variable phosphorus (P) and/or potassium (K) nutrition, soybean cyst nematode, disease pressure, etc. and more than one of these plant stresses may be found within one field.

Recently, active canopy reflectance sensors have been used to determine the nitrogen (N) nutritional needs of wheat, corn and forage grasses. There has been less interest in application of the technology to...