Want more? Waste not!
It makes no difference whether a farmer is measuring out his or her fertilizer by the Coke bottle top, and applying it to an individual plant of sorghum or maize, or whether his or her tractor is fitted with computer controlled application equipment, guided by global positioning satellite. Efficient fertilizer use is of paramount importance to farmer and consumer alike.
This is particularly true in developing countries where fertilizer use has
been increasing continuously since the 1960s and now accounts for 60% of global
consumption. This trend will undoubtedly continue as greater priority is given
to increasing agricultural production, a trend stimulated by the food needs
of more people, greater demand for feed grains and a realization that development
depends as much upon agriculture as upon industry. Furthermore, every year
agricultural land is lost; to soil erosion, salinity and other forms of land
degradation, and to urban development. The amount of additional, unforested
land available, with an adequate supply of water, is now very limited. More
will have 
to
be produced on less and this will be impossible without better use of fertilizer.
Better use depends upon better understanding. A good example is nitrogen which most farmers are keen to apply. It is relatively low cost, widely available and plants respond quickly. What is less often properly recognized is that the increased yields more rapidly deplete the soil of the other plant nutrients removed in the harvested crops, a factor not reflected in the commodity price. Yields of rice paddy, for example, may increase three-fold with the application of adequate nitrogen but this will result in the removal of 2.6 times more phosphorus, 3.7 times more potassium and 4.6 times more sulphur from the soil (IRRI). Unless these nutrients are replaced, yields stagnate. The same applies to micronutrients. Unless fertilization is balanced, not only is potential revenue lost but much of what has been applied may be a waste of money and an environmental hazard.
Coupled with the need to improve fertilizer use is the need to make more efficient use of water. Agricultural irrigation uses two-thirds of the world's supply of developed water. It seems likely that, over the next few decades, the number of regions facing severe problems in meeting their needs for water will increase and some of these regions, for example the Indian Punjab and the central plain of China, are among the most important agricultural producing regions of the world. Crops that are healthy and growing well derive maximum benefit from, and therefore make most efficient use of, irrigation water and therefore provide the best economic return on the cost of its provision. Wasted water is as costly as wasted fertilizer.
The world owes much to the use of inorganic fertilizers. Consider the amount of land that has been 'saved' by increasing productivity over the last thirty years. Over the next thirty years the priority must surely be to use fertilizer more efficiently and thereby to increase agricultural production per unit of fertilizer, water - and human effort - applied.
