Soil is formed from the physical and chemical weathering of rocks-processes described historically becau'se they involve eons of time-by glaciation and by wind and water transport of soil materials, which are later deposited in deltas and loessial planes. Soil undergoes further transformations over time and provides a habitat for biological life and a base for the development of civilizations. Soil is dynamic-always changing as a result of the forces of nature and particularly by the influences of man. Soil has been studied as long as history has been documented. Numerous references to soil...

The purpose of Advances in Soil Science is to provide a forum for leading scientists to analyze and summarize the available scientific information on a subject, assessing its importance and identifying additional research needs. A wide array of subjects has been addressed by authors from many countries in the initial ten volumes of the series. The quick acceptance of the series by both authors and readers has been very gratifying and confirms our perception that a need did exist for a medium to fill the gap between the scientific journals and the comprehensive reference books. This volume is...

The study of soils today has taken on increased importance because a rapidly expanding population is placing demands on the soil never before experienced. This has led to an increase in land degradation. Land degradation is one of the most severe problems facing mankind. Volume 11 of Advances in Soil Science was devoted entirely to this critical area of soil science. From the beginning of agriculture until about 1950, increased food production came almost entirely from expanding the cropland base. Since 1950, however, the yield per unit of land area for major crops has increased dramatically....

Soil is formed from the physical and chemical weathering of rocks-processes described historically because they involve eons of time-by glaciation, and by wind and water transport of soil materials, later deposited in deltas and loessial planes. Soil undergoes further transformations over time and provides a habitat for biological life and a base for the development of civilizations. Soil is dynamic - always changing as a result of the forces of nature and particularly by the influences of man. Soils have been studied as long as history has been documented. W. H. Gardner told of writings on...

The world needs for food and fiber continue to increase. Population growth in the developing countries peaked at 2. 4 percent a year in 1965 and has fallen to about 2. I percent. However, in many developing countries almost half the people are under 15 years of age, poised to enter their productive and reproductive years. The challenges to produce enough food for this growing population will remain great. Even more challenging is growing the food in the areas of greatest need. Presently the world has great surpluses of food and fiber in some areas while there are devastating deficiencies in...

The world population in 1950 was 2. 5 billion and is more than 5 billion today. The agriculture community, however, has responded remarkably well to meeting the increased need for food and fiber. While the population growth during this period averaged almost 2% annually, the production of grain increased at an even faster rate. From 1950 to 1973, grain production increased 3. 1% annually, but slowed to about 2% from 1973 to 1984. There fore, as a whole, the world has more grain per capita available today than ever before. Several countries that were food importers just a few years ago are...

The world population in 1930 was 2 billion. It reached 3 billion in 1960, stands at 4. 6 billion today, and is expected to reach 6 billion by the end of the century. The food and fiber needs of such a rapidly increasing population are enormous. One of the most basic resources, perhaps the most basic of all, for meeting these needs is the soil. There is an urgent need to improve and protect this resource on which the future of mankind directly depends. We must not only learn how to use the soil to furnish our immediate needs, but also ensure that the ability of the soil to sustain food...

The world population in 1930 was 2 billion. It reached 3 billion in 1960, stands at 4. 6 billion today, and is expected to reach 6 billion by the end of the century. The food and fiber needs of such a rapidly increasing population are enormous. One of the most basic resources, perhaps the most basic of all, for meeting those needs is the Soil. There is an urgent need to improve and protect this resource on which the future of mankind directly depends. We must not only learn how to use the soil to furnish our immediate needs, but also ensure that the ability of the soil to sustain food...

The world needs for food and fiber continue to increase. Population growth in the developing countries peaked at 2. 4 percent a year in 1965, and has fallen to about 2. 1 percent. However, in many developing countries almost half the people are under 15 years of age, poised to enter their productive and reproductive years. The challenges to produce enough food for this growing population will remain great. Even more challenging is growing the food in the areas of greatest need. Presently the world has great surpluses of food and fiber in some areas while there are devastating deficiencies in...

The world needs for food and fiber continue to increase. Population growth in the developing countries peaked at 2. 4% a year in 1965 and has fallen to about 2. 1%. However, in many developing countries almost half the people are under 15 years of age, poised to enter their productive and reproductive years. The challenges to produce enough food for this growing population will remain great Even more challenging is growing the food in the areas of greatest need. Presently the world has great surpluses of food and fiber in some areas while there are devastating deficiencies in other areas....