The red soils of China are typical in their chemical, physical and mineralogical characteristics of red soils in other tropical and sub-tropical areas of the world, particularly in South America, Africa and south-east Asia. For the most part, these soils are highly weathered and inherently infertile. They are acidic, nutrient deficient, poor in organic matter and have a low water-holding and supplying capacity. They cannot sustain arable cropping systems without the most careful management and are highly susceptible to soil erosion, particularly on sloping land. It is the purpose of this book to present recent research showing how the problems associated with using the red soils in China for sustainable agricultural production can be overcome, using a variety of traditional and novel approaches. In principle, these approaches should be useful in other tropical and sub-tropical countries faced with the problem of making the best use of their fragile red soil resources. The term "in principle" is used deliberately because, of course, the different red soil countries invariably operate within dissimilar socio-economic frameworks. At the present time, China may be considered to be in the process of an "industrial revolution", rather like that that took place in Britain in the late eighteenth and early nineteenth centuries.

The red soils of China are typical in their chemical, physical and mineralogical characteristics of red soils in other tropical and sub-tropical areas of the world, particularly in South America, Africa and south-east Asia. For the most part, these soils are highly weathered and inherently infertile. They are acidic, nutrient deficient, poor in organic matter and have a low water-holding and supplying capacity. They cannot sustain arable cropping systems without the most careful management and are highly susceptible to soil erosion, particularly on sloping land. It is the purpose of this book to present recent research showing how the problems associated with using the red soils in China for sustainable agricultural production can be overcome, using a variety of traditional and novel approaches. In principle, these approaches should be useful in other tropical and sub-tropical countries faced with the problem of making the best use of their fragile red soil resources. The term "in principle" is used deliberately because, of course, the different red soil countries invariably operate within dissimilar socio-economic frameworks. At the present time, China may be considered to be in the process of an "industrial revolution", rather like that that took place in Britain in the late eighteenth and early nineteenth centuries.

The study of soil nitrogen has long been an active field, but it was generally pivoted on agricultural and forestry production, and animal husbandry. With the rapid increase in the use of fertilizer nitrogen, more attention has been paid to the rela tionship between nitrogen management and environmental quality and human of soil nitrogen has become more comprehensive with health. In addition, the study the development of related sciences. The quantitative study of the processes in nitrogen cycling and their interrelationships has been an important part of this project and has attracted the attention of scientists allover the world. Nitrogen is one of the most important nutrients for plant growth and the applica tion of fertilizer nitrogen is playing an important role in agricultural production. The annual consumption of fertilizer nitrogen in the world has reached 70 million tons, and China has an annual consumption of more than 15 million tons and is the largest fertilizer nitrogen consumer in the world. However, the efficiency of nitro gen fertilizer is low and losses are large. It is estimated that nitrogen losses from agriculture in our country can be as high as 40-60% of the nitrogen applied. Some of the lost nitrogen enters the atmosphere and contributes to the greenhouse effect and some enters water bodies to pollute the water.