Physiolophy and terminology. Basic elements of dynamic simulation. A simulation language: Continuous system modeling program III. The growth of yeast. Additional exercises I. Numerical intergration and error analysis. Aspects of structured programming using CSMP and Fortran. Modelling of ageing, developmemt, delays and dispersion. Mass flow, numeral dispersion and diffusion. Simulation using Fortran. Additional exercises.

A system may be studied by distinguishing its major components, characterizing the changes in them by differential equations that form their simplified representa tions, and then interconnecting these representations to obtain a model of the original system. Developing the model is the systems synthesis phase. The behaviour of the model may now be studied and compared with experimental results obtained from the system. This research method is called systems analysis and simulation. Systems analysis and simulation can serve to make predictions, to improve the insight in systems, and to test knowledge on consistency and completeness. Predictive models are rare in ecology, simply because the underlying processes which form the basis of the models are seldom well known. A successful example of a predictive model was the work of van Keulen (1975). He showed that under semi arid conditions, where water is the main factor controlling primary production, the simulation technique could predict the production of natural grasslands. Fair predicti ons could also be made for the Sahelian pastures (Penning de Vries & Djiteye, 1982). Predictive models of populations of different pest and disease organisms are being used in biological control systems (Zadoks et aI., 1984).

This specially compiled volume contains contributions from Wolf Prize laureates. In agriculture, there is no higher prize than the Wolf Prize. The book includes a list of publications and the most important papers in plant and animal breeding, genetics, biochemistry and plant protection, biotechnology, as well as chemistry and the physics of soils.

This book synthesizes knowledge from several fields that are crucial to sustainable rural development: the physical environment, biological and agricultural production, rural sociology and economics. It takes a systems perspective incorporating systems analysis, landscape analysis and soil, water, and land planning. Directed toward graduate students and professionals, it provides a source of information and concepts for those concerned with land and water policies and practice. It presents an integrated approach using practical and applicable models and methods and takes a middle position between an elementary conceptual approach to land and water management and a highly mathematically advanced treatise based exclusively on system modeling. The book is based on almost twenty years of experience in teaching a course on rural planning and the environment, the authors being specialists from universities, research institutions and companies in Europe and North America.

We dedicate this book to professor C. T. de Wit (1924 - 1993) who initiated Production Ecology as a school of thought at the Wageningen Agricultural Univer sity (see Rabbinge et at. , 1990). To acknowledge the leading role of C. T. de Wit, a recently formed graduate school at this university in Production Ecology was named after him. Production Ecology is the study of ecological processes, with special attention to flows of energy and matter as factors that determine the productivity of ecological systems. Agro-ecosystems are a special case of ecosystems which are much better suited for the productivity approach than natural ecosystems are. This is the reason for the strong role of agricultural research in production ecology. On the other hand, it must be recognized that the spatial heterogeneity of natural ecosys tems and their species richness may alter some ecophysiological relationships. However, the basic physical, chemical and physiological processes will be the same. De Wit introduced the state variable approach as the basis for simulation mod elling. In this approach the floating character of nature is schematized into a series of snapshots over time in which the states are frozen at each separate moment. The current state determines how the rates of change will lead to the next snapshot. This way of thinking enables a clear and workable representation of interacting simul taneous processes, without compromising on the mathematics.

Proceedings of the 2nd International Potato Modeling Conference, held in Wageningen, 17--19 May, 1994

This book gathers review articles that analyze current agricultural issues and knowledge, then propose alternative solutions. It will therefore help all scientists, decision-makers, professors, farmers and politicians who wish to build a safe agriculture, energy and food system for future generations.

"This book brings computing solutions to ancient practices and modern concerns, sowing the seeds for a sustainable, constant food supply, utilizing cutting-edge computational techniques"--Provided by publisher.