Soil is formed from 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 human influences. The soil has been studied as long as history has been documented. Numerous references to soil are found in historical writings such as Aristotle (384-322 B. c. ), Theophrastus (372-286 B. c. ), Cato the Elder (234-149 B. C. ) and Varro (116-27 B. c. ). Some of the earliest historical references have to do with erosional forces of wind and water. 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 and desertification. Desertifica tion is largely synonymous with land degradation but in an arid land context. Deterioration of soil resources is largely human induced. Poverty, ignorance, and greed are the indirect causes of desertification. The direct cause is mismanage ment of the land by practices such as overgrazing, tree removal, improper tillage, poorly designed and managed water distribution systems, and overexploitation."

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. Economic conditions and the lack of suitable infrastructure for distribution all too often limit the alleviation of hunger even when there are adequate supplies, sometimes even within the country itself. World hunger can be solved in the long run only by increasing crop production in the areas where the population is growing most rapidly. This will require increased efforts of both the developed and developing countries. Much of the technology that is so successful for crop production in the developed countries cannot be utilized directly in the developing countries. Many of the principles, however, can and must be adapted to the conditions, both physical and economic, of the developing countries.

The steadily increasing cost of nitrogen fertilizer has resulted in more emphasis on basic and applied studies to improve nitrogen use efficiency in lowland rice. The efficiency of fertilizer nitrogen in farmers' fields is shockingly low ~ a luxury resource-scarce farmers in tropical Asia can ill afford. We believe it is critical to quantify the basic transformation processes and develop management practices for higher N use efficiency for two reasons. They are: 1. Nitrogen fertilizer together with water management is a key factor for achieving the yield potentials of modern rices. 2. Fertilizer nitrogen prices are high and most Asian rice farmers are poor. The International Rice Research Institute (IRRI), Philippines; Internation al Fertilizer Development Center (IFDC), USA; Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia; U.S. Universities (Louisiana, Cornell, California, Arkansas and others); and Dr Justus Leibig University in West Germany are actively engaged in individual or collaborative research that addresses basic transformation processes on N gains and losses and management practices to maximize N use efficiency in rice. It is appropriate to update and summarize, in a double issue of Fertilizer Research, the 10 papers presented at the special symposium organized by the American Society of Agronomy (ASA) at the 75th Annual Meeting in Washington, D.C. in 1983. S.K. De Datta, Head of Agronomy Department, IRRI, was chairman of the International Agronomy Division of ASA (A-6) in 1982 and 1983.

The International Society ofSoil Science was organized in 1924 and the 1st International Congress ofthe Society was held in Washington, D. C. , United States ofAmerica, in 1927. The 14th Congress was held August 12-18, 1990 in Kyoto, Japan. Dr. Akira Tanaka, Society President, stated "It is a serious concernofpeopleintheworldtosustainhighfarming productivityfor feeding the ever growing population,and also to protect the environment for human habitation. For this purpose, it is necessary to maximize crop yield per unit field areathroughintensivemanagementofthesoilandcropsonlands which are best suited for crop production, and to leave lands which are suboptimal for crops under natural conditions insofar as possible. Soil science is respon- siblefor planningtheoptimumland-usesystem,for managing soilsand crops with maximum efficiency, and for fighting intelligently against soil deteriora- tion. " Dr. Tanaka clearly stated the challenges facing soil scientists, and they are indeed challenges. Even though the rate ofworld population growth has decreased somewhat in recent years, the consensus is that total population willdouble-to some ten billion-beforeit stabilizes. The increased produc- tion of food, fiber, and fuelwood necessary for the people will require a continued supply ofnew technologies and management practices. The consensus of many scientists is that the greatest challenge is not increasing production, but preventing serious deterioration of the soil and waterresource base so theproductionlevel can be sustained. Therearemany historical examples where civilizations were successful for extended periods onlytoseesoildegradationleadtotheircollapse.

Forty years ago, when PLANT AND SOIL first appeared, Europe was still recovering from the devastating effects of World War II. During the war years, work in many centres of agricultural research had come to a virtual standstill. Buildings and equipment were destroyed, scientists were often forced to terminate their research and teaching activities and funds allocated to such work were diverted to other, at that time, more pressing needs. During the first post-war years reconstruction was undertaken with great zeal and in that light the founding of the new journal PLANT AND SOIL must be viewed. In the pre-war period most agricultural science journals were still primarily national ones and consequently many articles were published in languages mastered by only a limited number of potential readers. In small countries whose languages are not widely understood, the desire arose to publish research findings in one of the major languages. It is therefore understandable that in the early years of the journal's existence, large portions of PLANT AND SOIL were filled with articles from the Scandinavian countries and The Nether lands. Originally, rather frequent use was made of the opportunity to publish also in German and French, but with the advance of English as a major language of communication, a decline was noticeable in the number of German and French manuscripts submitted. As a consequence the Edi torial Board has recently decided to terminate the publishing of articles in these languages."