The world's population is growing by 1,000 million a decade at current rates. This is putting tremendous stress on global resources such as agricultural land, that is increasingly needed to feed the rapidly growing global population. A relatively small proportion, or about 22% of Earth's total land area is potentially arable. Yet, every year an estimated 6-7 million hectares of agricultural land is made unproductive because of erosion, 1,5 million hectares is affected by reduced productivity because of waterlogging, salinization and alkalinization, and almost 1 million hectares, much of it prime land in rain-fed areas, is being lost to urbanization. In addition, prior to this century almost all increases in food production were achieved by bringing new land into production, though this is no longer possible because the cost of bringing additional land into production, both economically and ecologically is so high. Thus, while there are 3,300 million hectares of potentially arable land globally, bringing it all into production, which would be required at current agricultural yields to feed 12,000 million people, is not a viable option. Indeed, increases in land under cultivation decreased from 4,4% in the 1960s to less than 2% during the 1980s. Since increasing agricultural land in concert with population growth is impossible, agricultural land continues to be lost, and the global population continues to grow rapidly, it is widely agreed that in addition to protecting the most productive and fertile agricultural land, agricultural yields per acre need to be significantly increased.
Yields increased relatively slowly until genetics and plant breeding initiated the so called "green revolution," thanks to which yields have increased at about 2.1% per year. This has reduced the average amount of land per capita required to feed people to 0.26 hectares. However, those yields are typically achieved with intensive use of water, pesticides and fertilizers that have created serious environmental and resource problems, and many of the world's farmers do not have these inputs for lack of finances, resources, and technical training. These biotechnological and conventional agricultural methods are furthermore achieving less incremental gains per unit of research and inputs, illustrating that these upward trends cannot continue indefinitely. The incremental response to pesticides, fertilizers, and other inputs is decreasing, and during the past decade and a half, maximum yield trails of rice have been stuck at 8 to 12 thousand kgs per hectare. Maximum corn yield are increasing only linearly and not exponentially. Conventional animal breeding has produced animals that convert a higher proportion of their feed to meat, to a point.