Does anyone make a yeild monitor that would  work like a combine.  Something that i could could check and find week spots in alfalfa feilds.  Its easy to just count the bales to determine week spots but not really know just how much weight differents there is on parts of fields. I would like to be able to go back and add fertilizer to these acers that are weak after the bales are picked up.  Something that would map out and show me yeild from  each field   Any thoughts??