Ammonium nitrate is one type of inorganic fertilizer used to provide nitrogen to lawns. According to the University of Minnesota Extension, most lawns require nitrogen fertilizer periodically to remain green and lush. However, applying nitrogen fertilizer also requires caution, as misapplication can damage both your lawn and the local ecosystem.
Nitrogen is one of three primary nutrients that plants, including grass, need to survive. Nitrogen is an essential component of all cells and is required for processes that use energy, as well as playing a role in plant growth, seed and fruit production and photosynthesis. Among the three commonly used inorganic nitrogen lawn fertilizers, ammonium nitrate delivers the most nitrogen. Up to one-third of what you put on your lawn contributes nitrogen to the grass.
According to the University of Minnesota Extension, ammonium nitrate is a water-soluble or fast-release fertilizer, which means that as soon as you water your lawn, the nitrogen in the fertilizer becomes available. Ammonium nitrate, therefore, quickly shows an effect, although the effect is also relatively short-lived. Furthermore, because of ammonium nitrate's high solubility, it has potentially harmful effects for the local environment as well.
Because ammonium nitrate is a highly soluble, fast-release fertilizer, it also has high potential for burning your lawn if over-applied. Burning occurs when fertilizers leave salts in the soil that draw water from the grass, leaving the grass yellow and dried, appearing burned. Ammonium nitrate may also leach into groundwater or run off into surface water supplies, causing pollution. Always follow fertilizer recommendations and instructions when applying ammonium nitrate.
Fast-release fertilizers like ammonium nitrate have advantages and drawbacks, according to the University of Illinois Extension. If you want a quick greening effect or need to apply fertilizer to cold soil, ammonium nitrate may be a good choice. Ammonium nitrate also tends to be inexpensive. For more uniform, long-term effects less likely to harm your lawn or the environment, ammonium nitrate would not be the best choice, and a slow-release fertilizer would be advisable.
The University of Minnesota Extension reports that several factors influence how much ammonium nitrate fertilizer your lawn needs. Some species, such as Kentucky bluegrass and perennial ryegrass, need more application than other low-maintenance lawn types. If you leave grass clippings on your lawn, you will need to apply less fertilizer, since the clippings act as a natural source of nitrogen. Over-watering can cause nitrogen to leach into the groundwater.