Ideally horses should be removed from newly fertilized pastures and be reintroduced to the pasture after a light rain. However, that may not be feasible due to housing space for the horse(s). Under normal conditions when ammonium nitrate (33%N) is used and a good even distribution of fertilizer is obtained, there should not be a threat to horses in that pasture. Horses have a greater tolerance to nitrogen than most people think (Meadows et al., 1978). However, if a fertilizer truck dropped a big pile of urea (82%N) on the pasture and the horse consumed a large quantity of the fertilizer, a problem could persist. With proper spreading of fertilizer and under normal conditions, a horse grazing recently fertilized pasture will not even have loose manure as a result.