Over the past 50–60 years, unbridledgrowth in global fertilizer use to boost and maintain cropyields has polluted natural and agricultural systems,leading to a range of harmful outcomes. The abundant andinefficient application of fertilizer is a leading cause ofwater pollution, as well as a contributor to greenhousegases and the deterioration of air and soil quality. This,in turn, has adverse consequences for public health, theclimate, wildlife, and business—including tourism,agribusiness, commercial fishing, and farming. Although itsuse, in combination with other Green Revolutiontechnologies, is credited for feeding the world and avertinga more dramatic expansion of agriculture into naturallandscapes, today’s fertilizer use is considered to bepushing the planet’s biogeochemical boundaries.