It is possible. However, getting accurate yield data requires a "smart" harvester that can produce yield maps. Many modern harvesters are equipped with GPS and various sensors, so it is possible. However, farmers are really slow to replace old equipment if it works fine. I guess there are some retrofit solutions for yield mapping, but I haven't investigated their affordability and penetration into the (EU) farming landscape yet. Additionally, there are other interesting parameters apart from the harvested quantity that can be captured (e.g. the quality of the grain itself, such as size, composition, humidity etc).