註釋 Currently the world population of 6 billion is suffering from a malnutrition crisis (WHO, 1996). The World Health Organization reports that more than half of the world population or more than 3 billion people are malnourished (WHO, 1996) - the largest number and proportion ever. This ominous report should focus the attention of all agriculturists on the importance of grains and tuber production, both now and for the future. The cool wet regions of the Northern and Southern Hemispheres supply nearly 70% of the world's food as measured by grains, and grains provide an estimated 80% to 90% of the world's food nutrients. Grains, like maize and wheat, can yield 8.000 kg and 7,000 kg respectively per hectare on average in North America and Europe. To achieve high yields, such as those above for maize and wheat, about 1,000 mm of rainfall and a temperature that ranges from 25 to 30 degrees C are needed. In addition, to achieve these high grain yields, large inputs of fertilizers and pesticides are required, both of which depend on continuing supplies of natural gas and oil. Environmental degradation, a serious problem in Northern-Hemisphereagriculture, is emerging as a serious constraint to achieving high yields. The most serious problems are soil erosion, water runoff, depletion of soil organic matter, and loss of biodiversity in the environment. Also of importance are chemical pollution problems, especially the environmental impacts of pesticides. Technologies are now available that would help conserve soil, water, nutrients, organic matter, and soil biota. In addition to making agriculture environmentally sound, adopting these techniques would reduce fossil energy inputs by about a half, reduce production costs about 36%, while at the same time slightly increasing crop yields. Therefore, to make agriculture environmentally sustainable and profitable, every effort should be made to develop and adopt soil and water conservation technologies. Worldwide, a balance must be found between human population numbers, food supply and the essential natural resources that make the production of adequate food possible. 