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Greenhouse climate control. An integrated approach
AGRICULTURAL AND FOREST METEOROLOGY
ELSEVIER
Agricultural
and Forest Meteorology
80 ( 19%) 299-30
1
Book review Greenhouse Climate Control. An Integrated Approach. J.C. Bakker, G.P.A. Bot, H. Challa and N.J. Van de Braak (Editors), Wageningen Pers, Wageningen, The Netherlands, 1995. 279 pp., ISBN 90-74134-17-3.
Agricultural meteorology makes an impact on agricultural production by guiding farmers on adaption of cultivation methods to existing conditions. In the confined space of a greenhouse, the same knowledge allows a more active intervention: changing the internal microclimate to suit plant requirements. Meteorologists such as Businger and Waggoner, who pioneered the quantitative approach in the study of plant shelter microclimate, have recognized its dependence on the combined effects of weather, greenhouse structure and equipment, and plants grown inside. Therefore, the proper climate control of greenhouses requires a close interaction between agrometeorologists, plant physiologists and engineers. The present book on greenhouse climate control is the product of such an interaction. Considering that each individual contributor to the book is a leading expert in his field, and that this expertise has developed through theoretical, experimental and practical work in greenhouses, one would expect a book summing up the current state of the art. Although the information is at the forefront of the knowledge, its main sources are the immediate surroundings of the individual contributors. Whereas references cover well general crop physiology, environmental engineering and physics, the book bypasses a considerable body of greenhouse specific publications. This is regrettable because a good bibliography is a prerequisite for the interdisciplinary integration to which the book is committed. The style is didactic. It introduces concepts, defines terms, specifies units and dimensions. Although the details pertain to general science, the focus is on greenhouses. The systematic theoretical framework adopted through most of the book will limit its audience to graduate students and scientists, but will include the target audience of Agricultural and Forest Meteorology The first chapter describes the economical importance of greenhouse cropping in the World. The status of the Netherlands as the country with the largest greenhouse industry explains why this book was written by Dutch scientists. Five densely written, technical and scientific chapters of uneven length follow this introduction. Each chapter is subdivided in topics organized according to a logical outline. Yet it is not easy to find all the relevant information in one location. As different contributors wrote the sections 0168-1923/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 0168- 1923(95)02308-9
composing a chapter, related information may be spread over several sections. There are also some unavoidable redundancies. Chapter two on crop growth occupies one third of the book. It is a full course on crop developmental physiology, covering photosynthesis, respiration, plant water relations, biomass accumulation and partitioning, and morphology. The reader will find there the mathematical functions for quantifying these processes. Yet, he will be forced to scan the text very carefully for the numerical values of the functions’ parameters. The chapter includes a section on coupling between water status and carbon assimilation. The importance of this subject arises from the role of stomata on the regulation of water vapour and carbon dioxide transport. Yet, it overlooks the influence of the greenhouse environment on these two transport processes. The section on product quality is in sharp contrast with the rest of the chapter. It adopts a simple factual description of individually observed effect of environmental factors on product quality. It also reveals the area with the widest knowledge gap. The treatment of the physics of the greenhouse climate in Chapter three suffers from a lack of insight. Its section on transport phenomena summarizes material found in any undergraduate text on heat transfer. The section on the energy balance gives a brief overview of the effects of the greenhouse on its internal microclimate, but fails to convey the specificity of the greenhouse physical environment. The chapter is beefed up by sections dealing with the physical aspects of water vapour and carbon dioxide balance. This material relates to sections in Chapter two, but the reader must establish the link himself. Chapter four is about nuts and bolts. The information is practical. It explains the pros and cons of the adopted engineering solutions to various design problems encountered in the construction and the equipment of a greenhouse. The emphasis is on design fitted to the climatic conditions and the technological traditions of the Netherlands. Yet, the systematic presentation allows translation of part of the Dutch experience to other environments. The sophistication of greenhouse cropping derives from the possibility to operate various devices that modify the internal microclimate. Effective regulation of the climatic variables is the objective of Chapter five. Climate control is also associated with automation. The reader is exposed to the principles ruling proper functioning of control systems. It starts from the sensing elements that monitor the controlled variables, their relation to set points, and their role in feedback loops. Sophisticated systems are exposed to breakdowns. A section, devoted to malfunctions and preemptive actions, is missing here. The conclusion of the chapter points out that control and automation functions do not include a set point for the growers’ objective of making as much money as possible. This viewpoint summarizes the need to integrate the information presented in the book in an optimization scheme that would include construction design, equipment, cultivation methods, and environmental control. It introduces the last chapter which tries to put everything to work together. This effort is probably the most difficult to formalize in text, although every grower, in his greenhouse makes this integration. Still, we know, that growers working in the same conditions, and with the same inputs, will obtain very different results. The book sets the development of design and decision making tools as the next research challenge.
Book Review
301
Excellent illustrations and an attractive typographical layout are important assets of the book. Still, some graphs used to visualize concepts lack proper axis labelling. They seem to have been extract from lecture notes, but without the lecturer’s comments their message remains obscure. The detailed table of contents and the index facilitate navigation through the book toward a specific subject matter. The text on the back cover gives a correct perspective of the book’s significance. It assigns to the presented material the role of background information for the development of a ‘new philosophy.. . to handle’ the ‘complex problem’ of greenhouse environment control. In the authors’ view, computers and models will be the tools serving this integrated approach. Still, the new way to process information is not revealed. It will probably become the subject of a book to be written ten years from now. M. Fuchs Agricultural Research Organization Institute of Soils and Water Bet Dagan Israel
ELSEVIER
Agricultural
and Forest Meteorology
80 ( 19%) 299-30
1
Book review Greenhouse Climate Control. An Integrated Approach. J.C. Bakker, G.P.A. Bot, H. Challa and N.J. Van de Braak (Editors), Wageningen Pers, Wageningen, The Netherlands, 1995. 279 pp., ISBN 90-74134-17-3.
Agricultural meteorology makes an impact on agricultural production by guiding farmers on adaption of cultivation methods to existing conditions. In the confined space of a greenhouse, the same knowledge allows a more active intervention: changing the internal microclimate to suit plant requirements. Meteorologists such as Businger and Waggoner, who pioneered the quantitative approach in the study of plant shelter microclimate, have recognized its dependence on the combined effects of weather, greenhouse structure and equipment, and plants grown inside. Therefore, the proper climate control of greenhouses requires a close interaction between agrometeorologists, plant physiologists and engineers. The present book on greenhouse climate control is the product of such an interaction. Considering that each individual contributor to the book is a leading expert in his field, and that this expertise has developed through theoretical, experimental and practical work in greenhouses, one would expect a book summing up the current state of the art. Although the information is at the forefront of the knowledge, its main sources are the immediate surroundings of the individual contributors. Whereas references cover well general crop physiology, environmental engineering and physics, the book bypasses a considerable body of greenhouse specific publications. This is regrettable because a good bibliography is a prerequisite for the interdisciplinary integration to which the book is committed. The style is didactic. It introduces concepts, defines terms, specifies units and dimensions. Although the details pertain to general science, the focus is on greenhouses. The systematic theoretical framework adopted through most of the book will limit its audience to graduate students and scientists, but will include the target audience of Agricultural and Forest Meteorology The first chapter describes the economical importance of greenhouse cropping in the World. The status of the Netherlands as the country with the largest greenhouse industry explains why this book was written by Dutch scientists. Five densely written, technical and scientific chapters of uneven length follow this introduction. Each chapter is subdivided in topics organized according to a logical outline. Yet it is not easy to find all the relevant information in one location. As different contributors wrote the sections 0168-1923/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 0168- 1923(95)02308-9
composing a chapter, related information may be spread over several sections. There are also some unavoidable redundancies. Chapter two on crop growth occupies one third of the book. It is a full course on crop developmental physiology, covering photosynthesis, respiration, plant water relations, biomass accumulation and partitioning, and morphology. The reader will find there the mathematical functions for quantifying these processes. Yet, he will be forced to scan the text very carefully for the numerical values of the functions’ parameters. The chapter includes a section on coupling between water status and carbon assimilation. The importance of this subject arises from the role of stomata on the regulation of water vapour and carbon dioxide transport. Yet, it overlooks the influence of the greenhouse environment on these two transport processes. The section on product quality is in sharp contrast with the rest of the chapter. It adopts a simple factual description of individually observed effect of environmental factors on product quality. It also reveals the area with the widest knowledge gap. The treatment of the physics of the greenhouse climate in Chapter three suffers from a lack of insight. Its section on transport phenomena summarizes material found in any undergraduate text on heat transfer. The section on the energy balance gives a brief overview of the effects of the greenhouse on its internal microclimate, but fails to convey the specificity of the greenhouse physical environment. The chapter is beefed up by sections dealing with the physical aspects of water vapour and carbon dioxide balance. This material relates to sections in Chapter two, but the reader must establish the link himself. Chapter four is about nuts and bolts. The information is practical. It explains the pros and cons of the adopted engineering solutions to various design problems encountered in the construction and the equipment of a greenhouse. The emphasis is on design fitted to the climatic conditions and the technological traditions of the Netherlands. Yet, the systematic presentation allows translation of part of the Dutch experience to other environments. The sophistication of greenhouse cropping derives from the possibility to operate various devices that modify the internal microclimate. Effective regulation of the climatic variables is the objective of Chapter five. Climate control is also associated with automation. The reader is exposed to the principles ruling proper functioning of control systems. It starts from the sensing elements that monitor the controlled variables, their relation to set points, and their role in feedback loops. Sophisticated systems are exposed to breakdowns. A section, devoted to malfunctions and preemptive actions, is missing here. The conclusion of the chapter points out that control and automation functions do not include a set point for the growers’ objective of making as much money as possible. This viewpoint summarizes the need to integrate the information presented in the book in an optimization scheme that would include construction design, equipment, cultivation methods, and environmental control. It introduces the last chapter which tries to put everything to work together. This effort is probably the most difficult to formalize in text, although every grower, in his greenhouse makes this integration. Still, we know, that growers working in the same conditions, and with the same inputs, will obtain very different results. The book sets the development of design and decision making tools as the next research challenge.
Book Review
301
Excellent illustrations and an attractive typographical layout are important assets of the book. Still, some graphs used to visualize concepts lack proper axis labelling. They seem to have been extract from lecture notes, but without the lecturer’s comments their message remains obscure. The detailed table of contents and the index facilitate navigation through the book toward a specific subject matter. The text on the back cover gives a correct perspective of the book’s significance. It assigns to the presented material the role of background information for the development of a ‘new philosophy.. . to handle’ the ‘complex problem’ of greenhouse environment control. In the authors’ view, computers and models will be the tools serving this integrated approach. Still, the new way to process information is not revealed. It will probably become the subject of a book to be written ten years from now. M. Fuchs Agricultural Research Organization Institute of Soils and Water Bet Dagan Israel