It’s the most efficient and thus most environmentally friendly choice.
Farmers use ammonia to obtain the element nitrogen. Ammonia is stored in its liquid form in a pressure tank at about 100 pounds per square inch, until it’s injected under the soil from a tank pulled by a tractor, carefully controlled by an intricate system of valves and meters according to the calculated requirements of the crop. As the ammonia is released from the pressurized tank into the distribution system, the sudden drop in pressure causes it to boil, releasing the elemental nitrogen that can be immediately used by fast-growing plants that demand a large supply of nitrogen.
Research shows nitrogen supplied as ammonia is used by crops as effectively as nitrogen from any other source. In fact, according to one estimate, to maintain soil fertility without such man-made sources of nitrogen, the 11 million tons of industrially created nitrogen that US farmers use each year, much of it supplied as ammonia, would have to be replaced by manure from approximately 1 billion additional cattle. Those cattle would require another 2 billion acres to feed. That feed demand would take roughly the entire continental United States.