Ammonia nitrate fertilizer is toxic, but only in direct contact. Ammonia nitrate is a 34-0-0 mix with only 34% nitrogen it is much less potent then anhydrous ammonia which contains 82% nitrogen. Ammonia nitrate is applied early to the soil and by harvest there are no traces of it left in the crops. It takes great amounts of nitrates to give a human nitrite poisoning.
The ammonium ion in the chemical compound is released as the chemical decomposes. If the ammonium ion concentration is too strong, plants can not absorb all the ammonia and the excess will burn the vegetation. Therefore, follow application rate calculations carefully when applying these types of fertilizers.
Nitrate in water can be toxic in heavy concentrations. Most states limit the amount of nitrate in drinking water and industrial facilities will be regulated for cleanup standards. Typically a nitrate concentration can not exceed 10 ppm for drinking water to be considered safe. Medical problems for young children is a known problem for high nitrates in drinking water.
