If the cows just graze on a field, their population density is so low that their urine isn't much of a problem. But when a number of tightly packed cows much higher than what the surrounding fields could ever support is converting huge amounts of imported fodder into their various outputs, then yes, everything but the milk quickly reaches environmental hazard concentrations. They tele-graze, but they don't tele-defecate. It's a real problem and it does not come as a surprise that the partial solution is from the Dutch who are taking high density agriculture to extremes like few others.