Nitrogen is among the most abundant elements on Earth. It comprises 78 percent of the Earth's atmosphere and is essential for all life forms. Since it is so abundant and important, one might wonder, "What is the problem with a little more nitrogen?" The issue is that most of the global nitrogen exists in its elemental gaseous form that is biologically unavailable to all organisms except those that can fix nitrogen (convert it to organic nitrogen), which include some bacteria, algae, and flowering plants (such as legumes). Most natural ecosystems have evolved under the constraint of a shortage of biologically available nitrogen. Read more