World population growth rate has slowed since the early 1970s, but growth in world grain production has slowed further. As a result, per capita grain production has declined since 1983. Conventional farming practices that use heavy chemical applications and high-yielding varieties have resulted in soil erosion, depletion of natural resources, contamination of the environment, and reduced biodiversity; and threaten to diminish the world's ability to sustain life of all kinds. If these trends persist, the earth may not sustain an adequate level of food production. Transition to sustainable agricultural practices could presumably prevent most of this degradation but may not produce adequate supplies of food to meet the growing demand. Although yields from sustainable agricultural farms can be as high as those from conventional farms, food production per acre of rotation generally declines because sustainable farms need to incorporate green manure crops and forage legumes into their rotations. Therefore, food production must be increased, which can be done in two ways: either bring more land into cultivation or increase yields. Although there are large tracts of land still available, their fragile ecosystems make it costly to bring them into production. Future grain production must come from higher yields. However, several studies indicate that the growth of major crop yields is leveling off, and that it has become increasingly difficult to increase crop yields. Therefore, to meet future world food demand, we need to continue to invest in research to develop new technologies that are directed toward sustainable agriculture. Adoption of new technologies could break through the yield ceiling characterized by previous technologies and enable the yield growth rate to outpace the population growth rate.
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