run offs can be a pain too. water doesnt just run straight down thru the soil it follows the easiest way down and drags what nutes or salts etc it hits along the way.
something is way off either the drops are screwed up or there is something in your water that is reacting with something in the soil. 8 soil/nute companies wouldnt be around very long if there soils were constantly toxic or contaminated. what do yo know about your water table and groundwater seepage? didnt you say you have a well? maybe there is something leaching into it. doesnt mean that it makes it unsafe for drinking etc. but it doesnt mean that there might not be something weird in there.