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Systems theory applied to agriculture and the food chain
Book rev~ws
101
further reading at the end of the book. This provides the reader with a clear route for expanding on the theory and application outlined in each chapter.
M. J. McGregor
Systems Theory Applied to Agriculture and the Food Chain. Edited by J. G. W. Jones and P. R. Street. Elsevier Applied Science, London, 1990. 365 pp. Price: £62.00 (hardback). ISBN 1 85166 510 2. This volume contains thirteen contributed papers to the symposium held in September, 1990, at the University of Reading, to commemorate the retirement of Professor Colin Spedding. This is a fitting way to pay tribute to a man who had much to do with the philosophical and other developments associated with the study of agricultural systems over the last 25 years or so. As the editors note, the net cast by the systems approach is wide indeed: from the study of biological processes, to agroecosystems, economics, the whole food chain, and education and extension. Systems thinking has had, and continues to have, a substantial effect on agricultural research and development, implicitly or explicitly. Its development was certainly timely. Current preoccupations with the environment, global climate change, sustainable agricultural development, and global trade, amply demonstrate that we live in times whose major problems are characterised by complexity and a potential for widespread impact. These are nothing if not systems problems. Is the full potential of systems thinking being brought to bear on such problems? The papers in this volume, written by authorities in their respective fields, indicate that there are still lessons to be learned, most notably in the way in which agricultural research is organised and carried out. With hindsight, the call for a multidisciplinary approach to problem solving, while acknowledging the powerful strictures of research careers embedded in individual disciplines, was always going to be one of the hardest parts of Professor Spedding's vision to respond to. As anyone knows who has attempted this, probably it still is. A slightly disappointing aspect of many of the papers assembled here is that there is little speculation on future developments. It is not easy to review the state of the art in a subject area where page space is at a premium, but some of the papers lack a little in this perspective. Despite this, the collection is impressive, and the range of themes treated is very wide. For anyone who wants an update on the systems approach in
102
Book reviews
agricultural research, the book will be required reading. Will the full implications of the systems approach become apparent in the future? Perhaps the next 25 years will tell.
P. K. Thornton
Modelling of Energy Forestry: Growth, Water Relations and Economics. Edited by K. L. Perttu and P. J. Kowalik. Pudoc, Wageningen, 1989. 198 pp. Price: Df 80.00 (hardback). ISBN 90 220 0947 5. This book brings together papers by thirteen scientists, mainly from the Swedish University of Agricultural Sciences in Uppsala. It includes descriptions of eight models of different aspects of energy forestry and overviews the main features and potentials of this form of land use in a Swedish context. Sweden is well suited for energy forestry, mainly because of the long day-length during the growing season and the availability of 400 000 hectares of agricultural-grade land. The main species is willow, which is managed by coppicing on a 3-5 year cutting cycle with replacement after 20-40 years. The main constraints on production are light, temperature, water and nutrients, with irrigation and fertilisation being the main management tools for increasing production. Four of the models relate to growth and production. They include an analysis of the response curve relating photosynthesis to light; a sevencompartment, carbon-based growth model; an analysis of the partitioning terms in this model; and a nitrogen-demand model. The three models of water relations in willow stands deal with the modelling of transpiration, evaporation and leaf temperature over very small time steps (one minute); the development of a less detailed model that can use daily weather data; and a multi-layered model of soil water-balance. The economic model enables the effect of different soil types and scale of cultivation to be explored: it leads to the conclusion that energy forestry is economically viable on small-scale holdings on good agricultural land. There are three commendable aspects of the modelling approach. First, the authors explicitly consider choices in modelling, rather than merely presenting one solution. Second, the various modelling groups work within a sin ;le modelling support package, developed by one of the authors and described in the Appendix. Third, FORTRAN listings are given for most of the models, enabling others to try them out. It is, however, odd to see that the economics model is not implemented in a spreadsheet, as one might expect.
101
further reading at the end of the book. This provides the reader with a clear route for expanding on the theory and application outlined in each chapter.
M. J. McGregor
Systems Theory Applied to Agriculture and the Food Chain. Edited by J. G. W. Jones and P. R. Street. Elsevier Applied Science, London, 1990. 365 pp. Price: £62.00 (hardback). ISBN 1 85166 510 2. This volume contains thirteen contributed papers to the symposium held in September, 1990, at the University of Reading, to commemorate the retirement of Professor Colin Spedding. This is a fitting way to pay tribute to a man who had much to do with the philosophical and other developments associated with the study of agricultural systems over the last 25 years or so. As the editors note, the net cast by the systems approach is wide indeed: from the study of biological processes, to agroecosystems, economics, the whole food chain, and education and extension. Systems thinking has had, and continues to have, a substantial effect on agricultural research and development, implicitly or explicitly. Its development was certainly timely. Current preoccupations with the environment, global climate change, sustainable agricultural development, and global trade, amply demonstrate that we live in times whose major problems are characterised by complexity and a potential for widespread impact. These are nothing if not systems problems. Is the full potential of systems thinking being brought to bear on such problems? The papers in this volume, written by authorities in their respective fields, indicate that there are still lessons to be learned, most notably in the way in which agricultural research is organised and carried out. With hindsight, the call for a multidisciplinary approach to problem solving, while acknowledging the powerful strictures of research careers embedded in individual disciplines, was always going to be one of the hardest parts of Professor Spedding's vision to respond to. As anyone knows who has attempted this, probably it still is. A slightly disappointing aspect of many of the papers assembled here is that there is little speculation on future developments. It is not easy to review the state of the art in a subject area where page space is at a premium, but some of the papers lack a little in this perspective. Despite this, the collection is impressive, and the range of themes treated is very wide. For anyone who wants an update on the systems approach in
102
Book reviews
agricultural research, the book will be required reading. Will the full implications of the systems approach become apparent in the future? Perhaps the next 25 years will tell.
P. K. Thornton
Modelling of Energy Forestry: Growth, Water Relations and Economics. Edited by K. L. Perttu and P. J. Kowalik. Pudoc, Wageningen, 1989. 198 pp. Price: Df 80.00 (hardback). ISBN 90 220 0947 5. This book brings together papers by thirteen scientists, mainly from the Swedish University of Agricultural Sciences in Uppsala. It includes descriptions of eight models of different aspects of energy forestry and overviews the main features and potentials of this form of land use in a Swedish context. Sweden is well suited for energy forestry, mainly because of the long day-length during the growing season and the availability of 400 000 hectares of agricultural-grade land. The main species is willow, which is managed by coppicing on a 3-5 year cutting cycle with replacement after 20-40 years. The main constraints on production are light, temperature, water and nutrients, with irrigation and fertilisation being the main management tools for increasing production. Four of the models relate to growth and production. They include an analysis of the response curve relating photosynthesis to light; a sevencompartment, carbon-based growth model; an analysis of the partitioning terms in this model; and a nitrogen-demand model. The three models of water relations in willow stands deal with the modelling of transpiration, evaporation and leaf temperature over very small time steps (one minute); the development of a less detailed model that can use daily weather data; and a multi-layered model of soil water-balance. The economic model enables the effect of different soil types and scale of cultivation to be explored: it leads to the conclusion that energy forestry is economically viable on small-scale holdings on good agricultural land. There are three commendable aspects of the modelling approach. First, the authors explicitly consider choices in modelling, rather than merely presenting one solution. Second, the various modelling groups work within a sin ;le modelling support package, developed by one of the authors and described in the Appendix. Third, FORTRAN listings are given for most of the models, enabling others to try them out. It is, however, odd to see that the economics model is not implemented in a spreadsheet, as one might expect.