The FAO estimates that 80% of future increases in food production will be due to improved productivity, rather than from clearing forests and reserves for farmland. The FAO has estimated that more than 33% of the improvement in cereal yields in the 70s and 80s was due to fertilizer use. (www.fao.org) Unless world population growth stops or most people change their diets the world can only feed its population by either intensifying agriculture or by converting more land from natural eco systems like rain forest into agricultural production.
Intensification, with higher yields of food per hectare of land, means that more nutrients must be replaced to maintain sustainable land use. Fertilizers underpin all productivity and it is clear that fertilizers really do feed the world.
The sustainability of agriculture requires that the nutrients removed from the soil in food and fibre are replaced; if they are not then soils will become unproductive, ground cover will be reduced and the risks of erosion and desertification are increased. However applied nutrients can also cause environmental problems if there are losses to waterways or the atmosphere.