It is becoming more relevant to explore soil biological processes in terms of their contribution to soil fertility. This book presents a comprehensive scientific overview of the components and processes that underpin the biological characteristics of soil fertility. It highlights the enormous diversity of life in soil and the resulting effects that management of land can have on the contribution of this diverse community to soil fertility in an agricultural context.

Annotation. Successful agroforestry requires an understanding of the complex relationship between trees, crops and soils. This book provides a review of both economic and biophysical aspects of soil use and research in agroforestry, with an emphasis on nutrient-poor forest and savanna soils. Key topics covered include the economics of soil fertility management, cycling of water, nutrients and organic matter, soil structure, and soil biological processes. The book combines synthetic overviews of research results and a review of methods used in research.From the foreword: 2The book is written within a particular context - soil fertility development under agroforestry. At first this may seem very specific and thus limited in appeal and application. But over the last decade or so agroforestry research has been one of the most influential in developing new insights into soil biology and fertility and thus provides a very suitable framework for review of progress. Furthermore the influence of trees on soil is profound and of significance beyond agroforestry systems, so the book is likely to be of interest in the wider spheres of agriculture, forestry and ecological sciences.3 Mike Swift, TSBF, Nairobi, Kenya.

This book reports on the first five years of research by scientists of the Tropical Soil Biology and Fertility Programme

The success of shifting cultivation systems developed by subsistence farmers testifies to the resilience of the "natural" soil-plant ecosystems to recover from the offtake of nutrients in crops and loss of soil struc ture. By contrast, the development of intensive cropping systems requires large inputs especially of nitrogen, together with phosphorus, sulphur and other essential elements in order to maintain the nutrient levels needed for abundant crop yields. As Dr. Cooke ably pointed out in his introductory lecture, the dis coveries and experiments of the 19th century encouraged farmers in temperate zones to rely greatly on chemical fertilizers supplements. However, the work of Charles Da{win on soil mixing by earthworms and the discovery by Hellriegel and Wilfarth in 1886 that the nodules on legume roots contain colonies of symbiotic bacteria able to "capture" atmospheric nitrogen molecules to the benefit of the host plant heralded a growing realization of the importance of soil biota in fertility studies. Biological fixation of nitrogen has been the theme of many meetings and publi~ations hitherto but at this Conference, convened on the delightful campus of Reading University, attention was mainly focussed on other biological processes in soil fertility. These Proceedings record the dominant themes and include six keynote addresses delivered at plenary sessions and seven introductory lectures to paper reading sessions by invited individuals plus 22 of the proferred papers, in six sections as tabled in the contents list.

In terrestrial ecosystems, soil microorganisms and soil animals are essential for litter degradation, soil formation and the availability of nutrients and trace elements. The measurement of biological soil parameters allows a rapid evaluation of the effects of chemical and physical influences due to pollutants or soil management. This book introduces a number of well proved methods for the analysis of carbon, nitrogen, phosphorus and sulfur cycles. It focuses further on the determination of the number and biomass of microorganisms, algae and animals in the soil. Particular emphasis is placed on the comprehensible and complete description of the experimental procedures.