"PRODUCTIVE AGRICULTURAL LAND is a finite and irreplaceable natural resource. Fertile soils take thousands of years to develop. Creating them takes a combination of climate, geology, biology and good luck. So far, no one has found a way to manufacture them." These words, written by the Farmland Information Center, aptly describe the importance of the earth's farmland. It is a resource whose value cannot even be measured because without fertile agricultural land, there would be no food for the world's people.

Of the 57 billion square miles of land on the planet, about 28 percent is devoted to agriculture. Over the years, humans have honed and perfected farming techniques. Technology has enabled farmers to get the most out of their land through the use of sophisticated machinery and irrigation equipment, and chemical fertilizers and pesticides have allowed them to dramatically increase crop...