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Climate, water and agriculture in the tropics
358
Concerning modeling per se, it is refreshing to read a book in which the author is careful to examine the limitations, as well as the strengths of modeling. He uses phrases such as "The construction of a simulation model is still as much an art as a science", and "Without proof of validity, a model, however elegant, may be nothing but a tentative exercise in abstract logic", and "... all models are approximations, none can be absolutely true, ...". Perhaps the author's caution stems from the fact that he, as well as this reviewer, "... received his basic training in the primitive, prehistoric, dark ages before computers appeared on the scene and became so ubiquitous and inescapable". Despite his 'dark ages' training, the author has prepared himself quite well in the use of computers to simulate soil--water dynamics. All of the programs listed are in CSMP language, but are given in sufficient detail that they could be adapted to the more universally used Fortran. Flow diagrams are presented, as well as program listings. The book is exceptionally readable. The author's style is such that interest is easily maintained throughout. The material is lightened by brief philosophical tidbits and quotations. The printing is offset from a typescript, and is essentially free of typographical errors (except for this reviewer's middle initial in a literature citation). It is available for $ 1 0 (Canadian). The book should be of interest to research workers and others concerned with agricultural and environmental aspects of the soil--water system. Researchers in related fields will find the discussion of the physics of the soil--water dynamics as valuable as the simulation modeling aspects. RAY D. JACKSON (Phoenix, Ar~iz., U.S.A.)
CLIMATE, WATER AND AGRICULTURE IN THE TROPICS
Climate, Water and Agriculture in the Tropics. I.J. Jackson.Longman, London, New York, N.Y., 1977, xii + 248 pp., 69 illustrations, U S $ 1 6 . 5 0 (cloth)/$ 8.50 (paper), ISBN 0-542-48529-0. Most of the underdeveloped or developing areas in our world are in or near the tropical regions, and are influenced greatly by tropical conditions. These conditions, in turn, are mostly dictated and characterized by two main elements - - c l i m a t e and water. Therefore, any approach to the study or to the improvement of these areas must be based on deep knowledge and understanding of the processes in which these two elements are involved. Many other factors, which are certainly important in their own right, such as infrastructure and economic conditions, agricultural production systems, and even political structures, are greatly influenced by climate and water, as can be clearly learned from the history of various ancient cultures. An impressive a m o u n t of data has been accumulated, mainly during the
359
last century, regarding the characteristics and mechanics of these factors. These data have long been scattered in a multitude of research reports and monographs, and quoted or summarized in many articles and texts dealing with global conditions, where the tropics were only a minor, relatively unimportant, part of the total. Only lately, with the focussing of the world's attention -- scientific and technical as well as political -- on the Third World, have efforts been made to collect, collate and arrange this mass in texts which deal specifically with the tropics. The present text is one of these efforts to fill the 'tropical gap' and study the physical processes from the viewpoint of tropical development. The book consists of three main sections. The first (Chapters 1 through 5) deals with the various elements of the tropical water balance and their interactions with the economic, social and political factors; special emphasis is placed on the human factors, such as the farmer's inertia in the face of innovations. The tropical circulation is carefully analyzed, disputing some of wide-spread theories of the inter-tropical convergence zone (ITCZ) as the main cause of the more important climatic phenomena in the tropics (mostly in the non-English European literature); instead, the notion of a series of disturbances is presented as the mechanism for water and energy transport, thus forming the basis for climatic changes. Rainfall is then extensively described and the details of the spatial and temporal, statistical and taxonomical properties of tropical rains are presented. The section ends in the discussion of evaporation -- its causes, its prediction, and its relationship to rainfall. The second part of the book (Chapters 6 to 8) deals with plant--water relationships and their implications to agriculture. A great part of this section is a general discussion, and only after that is the attention turned to the effects of the specific characteristics of tropical climate on plant behaviour. The last chapter in this section discusses the agricultural implications of the water balance -- its effects on the cultivation of specific crops, on soil erosion, and on irrigation practices in general and of tropical crops in particular; specially mentioned are bananas, coffee, maize, rice, sugarcane and tobacco. The last section of the book -- the 9th chapter -- is a discussion of Man's impact on the hydrological cycle, -- by such activities as rainfall stimulation and evaporation modification, as well as land-use practices and watershed management: a general discussion illustrated by examples from the tropics. In the preface, the text is described as expected to "broaden the knowledge" of "hydrologists, meteorologists, agriculturists and engineers, amongst others", as well as to be of help in their work to "planners, economists, geographers, sociologists, political scientists, administrators and others concerned with the wider aspects of development". The book is also supposed to be "relevant to university courses concerned with aspects of tropical water resources". Undoubtedly, the subject is multidisciplinary in nature, and there is a very real need for supplying any of the technicians
360
and scientists involved with the relevant information and understanding in subjects outside his immediate field of specialization. Unfortunately, the present text appears to have missed its mark; for example, the subject of c l i m a t e is necessarily covered here in a very superficial manner, certainly inadequate for a university student or for a practicing engineer; on the other hand, if previous knowledge of climatology and meteorology is assumed, most of the material in Chapters 3 and 4 is superfluous. The same goes for Chapter 6, which is insufficient for any reader unversed in plant-soil--water relationships, but is unnecessary for the reader who has studied the subject before, as well as for the discussion of irrigation of specific crops, in Chapter 7. It seems that the author should have concentrated his attention on tropical phenomena, problems and solutions (Chapters 2, 8 and 9 are good examples for this} and taken knowledge of the basic and general subjects for granted. Techniques tried and proven in the tropics should be emphasized; for example, the Blaney-Criddle method for estimating consumptive use, which has n o t proved itself under tropical conditions, should give way to such methods as the modified Turc formula, extensively used in Western Africa (and also in South America) but not mentioned here. Tropical conditions should serve as the basis for defining the tropical regions, replacing the geographical approach (of definition by latitude), and the regions classified and discussed separately under two or three headings -- the 'dry' and the ' h u m i d ' tropics (and, maybe, the 'wet and dry' tropics); this classification is presented (in section 8.3), but all phenomena are described and analyzed independently of it. Finally, this book, being a text and n o t a research report or a bibliographical review, suffers from the excess of references to sources (the book boasts an impressive list of some 350 references, some of them as late as 1973 and even 1974), and from the presentation of abundant data and sometimes conflicting information; the author of a t e x t b o o k is expected to provide his own conclusions, or at least to supply the reader with his own considered viewpoint. All this does not detract from the importance and vital need for a book like this; the high investment of all physical, economic and human resources in the development of tropical regions should certainly be based on a deep knowledge and understanding of all phenomena and processes specific to the tropics, rather than on the use of non-tropical techniques forced to fit tropical conditions. DOV N I R
(Haifa, Israel)
Concerning modeling per se, it is refreshing to read a book in which the author is careful to examine the limitations, as well as the strengths of modeling. He uses phrases such as "The construction of a simulation model is still as much an art as a science", and "Without proof of validity, a model, however elegant, may be nothing but a tentative exercise in abstract logic", and "... all models are approximations, none can be absolutely true, ...". Perhaps the author's caution stems from the fact that he, as well as this reviewer, "... received his basic training in the primitive, prehistoric, dark ages before computers appeared on the scene and became so ubiquitous and inescapable". Despite his 'dark ages' training, the author has prepared himself quite well in the use of computers to simulate soil--water dynamics. All of the programs listed are in CSMP language, but are given in sufficient detail that they could be adapted to the more universally used Fortran. Flow diagrams are presented, as well as program listings. The book is exceptionally readable. The author's style is such that interest is easily maintained throughout. The material is lightened by brief philosophical tidbits and quotations. The printing is offset from a typescript, and is essentially free of typographical errors (except for this reviewer's middle initial in a literature citation). It is available for $ 1 0 (Canadian). The book should be of interest to research workers and others concerned with agricultural and environmental aspects of the soil--water system. Researchers in related fields will find the discussion of the physics of the soil--water dynamics as valuable as the simulation modeling aspects. RAY D. JACKSON (Phoenix, Ar~iz., U.S.A.)
CLIMATE, WATER AND AGRICULTURE IN THE TROPICS
Climate, Water and Agriculture in the Tropics. I.J. Jackson.Longman, London, New York, N.Y., 1977, xii + 248 pp., 69 illustrations, U S $ 1 6 . 5 0 (cloth)/$ 8.50 (paper), ISBN 0-542-48529-0. Most of the underdeveloped or developing areas in our world are in or near the tropical regions, and are influenced greatly by tropical conditions. These conditions, in turn, are mostly dictated and characterized by two main elements - - c l i m a t e and water. Therefore, any approach to the study or to the improvement of these areas must be based on deep knowledge and understanding of the processes in which these two elements are involved. Many other factors, which are certainly important in their own right, such as infrastructure and economic conditions, agricultural production systems, and even political structures, are greatly influenced by climate and water, as can be clearly learned from the history of various ancient cultures. An impressive a m o u n t of data has been accumulated, mainly during the
359
last century, regarding the characteristics and mechanics of these factors. These data have long been scattered in a multitude of research reports and monographs, and quoted or summarized in many articles and texts dealing with global conditions, where the tropics were only a minor, relatively unimportant, part of the total. Only lately, with the focussing of the world's attention -- scientific and technical as well as political -- on the Third World, have efforts been made to collect, collate and arrange this mass in texts which deal specifically with the tropics. The present text is one of these efforts to fill the 'tropical gap' and study the physical processes from the viewpoint of tropical development. The book consists of three main sections. The first (Chapters 1 through 5) deals with the various elements of the tropical water balance and their interactions with the economic, social and political factors; special emphasis is placed on the human factors, such as the farmer's inertia in the face of innovations. The tropical circulation is carefully analyzed, disputing some of wide-spread theories of the inter-tropical convergence zone (ITCZ) as the main cause of the more important climatic phenomena in the tropics (mostly in the non-English European literature); instead, the notion of a series of disturbances is presented as the mechanism for water and energy transport, thus forming the basis for climatic changes. Rainfall is then extensively described and the details of the spatial and temporal, statistical and taxonomical properties of tropical rains are presented. The section ends in the discussion of evaporation -- its causes, its prediction, and its relationship to rainfall. The second part of the book (Chapters 6 to 8) deals with plant--water relationships and their implications to agriculture. A great part of this section is a general discussion, and only after that is the attention turned to the effects of the specific characteristics of tropical climate on plant behaviour. The last chapter in this section discusses the agricultural implications of the water balance -- its effects on the cultivation of specific crops, on soil erosion, and on irrigation practices in general and of tropical crops in particular; specially mentioned are bananas, coffee, maize, rice, sugarcane and tobacco. The last section of the book -- the 9th chapter -- is a discussion of Man's impact on the hydrological cycle, -- by such activities as rainfall stimulation and evaporation modification, as well as land-use practices and watershed management: a general discussion illustrated by examples from the tropics. In the preface, the text is described as expected to "broaden the knowledge" of "hydrologists, meteorologists, agriculturists and engineers, amongst others", as well as to be of help in their work to "planners, economists, geographers, sociologists, political scientists, administrators and others concerned with the wider aspects of development". The book is also supposed to be "relevant to university courses concerned with aspects of tropical water resources". Undoubtedly, the subject is multidisciplinary in nature, and there is a very real need for supplying any of the technicians
360
and scientists involved with the relevant information and understanding in subjects outside his immediate field of specialization. Unfortunately, the present text appears to have missed its mark; for example, the subject of c l i m a t e is necessarily covered here in a very superficial manner, certainly inadequate for a university student or for a practicing engineer; on the other hand, if previous knowledge of climatology and meteorology is assumed, most of the material in Chapters 3 and 4 is superfluous. The same goes for Chapter 6, which is insufficient for any reader unversed in plant-soil--water relationships, but is unnecessary for the reader who has studied the subject before, as well as for the discussion of irrigation of specific crops, in Chapter 7. It seems that the author should have concentrated his attention on tropical phenomena, problems and solutions (Chapters 2, 8 and 9 are good examples for this} and taken knowledge of the basic and general subjects for granted. Techniques tried and proven in the tropics should be emphasized; for example, the Blaney-Criddle method for estimating consumptive use, which has n o t proved itself under tropical conditions, should give way to such methods as the modified Turc formula, extensively used in Western Africa (and also in South America) but not mentioned here. Tropical conditions should serve as the basis for defining the tropical regions, replacing the geographical approach (of definition by latitude), and the regions classified and discussed separately under two or three headings -- the 'dry' and the ' h u m i d ' tropics (and, maybe, the 'wet and dry' tropics); this classification is presented (in section 8.3), but all phenomena are described and analyzed independently of it. Finally, this book, being a text and n o t a research report or a bibliographical review, suffers from the excess of references to sources (the book boasts an impressive list of some 350 references, some of them as late as 1973 and even 1974), and from the presentation of abundant data and sometimes conflicting information; the author of a t e x t b o o k is expected to provide his own conclusions, or at least to supply the reader with his own considered viewpoint. All this does not detract from the importance and vital need for a book like this; the high investment of all physical, economic and human resources in the development of tropical regions should certainly be based on a deep knowledge and understanding of all phenomena and processes specific to the tropics, rather than on the use of non-tropical techniques forced to fit tropical conditions. DOV N I R
(Haifa, Israel)