After 1950, in response to record growth in worldwide food demand, farmers worldwide sharply increased fertilizer use  As a result, the productivity of farmland more than doubled by 1985  Since 1985, farmers have sought to increase farmland productivity even further
Nevertheless, worldwide fertilizer use has declined by 6 percent between 1985 and the present
After fertilizer has been added to soil for several years, adding fertilizer to the soil in subsequent years does not significantly improve crop production.