In W. Europe, the consumption of fertilizers has increased 10-fold since 1910. Crop production has approximately doubled during this period. Fertilizers account for only about 10% of farming costs in W. Europe, but their effect on productivity is certainly 50% (Jung, 1979).

Up to one half the credit for the 3% average annual increase in world cereal grain production is assigned to the use of fertilizer N.

From 1940 - 1974 the value of the increase in yields achieved with fertilizers is given as $293 billion (U.S.) at a cost of $42 billion (benefit : cost ratio = $7 crop value for each dollar spent on fertilizer) (Hardy et al, 1975).

For trends in world fertilizer consumption see "Statistics" at the following URL: International Fertilizer Industry Association

Hardy RWF, Filner P, Hageman RH 1975 Nitrogen input. In (AWA Brown, TC Byerly, M Gibbs, A San Pietro eds) "Crop Productivity - Research Imperatives", Michigan-Kettering, pp. 133-176.

Jung J 1979 Possibilities of optimization of plant nutrition by new agrochemical substances - especially in cereals. In (TK Scott ed) "Plant Regulation and World Agriculture", Plenum Press, New York, pp. 279-307.