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Agricultural systems. An international journal
249
water when considering the availability of water in soil. Some techniques for measuring soil-water content and soil-water potential are then mentioned. The remainder of the chapter discusses the determination of water potential, water absorption and xylem sap exudation from roots. These sections are well illustrated with diagrams of the equipment. Chapter 4 moves onto the next stage in the process of water movement in the soil--plant--atmosphere continuum by discussing liquid water movement and'methods for measuring this liquid movement in the plant using three headings, hydraulic conductivity (velocity under unit pressure gradient) of cytoplasm, cell membrane, and parenchymatous tissue, velocity of water movement in the xylem and volume flux of water in xylem vessels. The techniques for velocity and volume flux discussed, however, apply only to the measurements of these values in trees. The final chapter (5) deals with water exchange between the plant and atmosphere. After a brief introduction to the general factors important in the water exchange process, i.e. energy balance of the plant surface, water potential gradient and flux resistance, methods for determining these factors are outlined. These include measurements of air humidity, water absorption by the aerial plant parts, transpiration, stomata and guttation. A summary is given of methods for measuring stomatal aperture and concludes the chapter. This book, as with all books which deal with techniques, is a welcome addition to literature and will be of considerable help to those wanting to find out how to make measurements in plant--water relations work. However, some of the techniques which are discussed at length are not necessarily the best to use for a particular measurement, e.g., the resistance block method of measuring soil moisture is discussed at length (over 10 pages) while tensiometers, which are more reliable in the wet range of soil water, are given less space. The reader should, therefore, be cautious when searching for techniques although the equipment lists and summaries offered will help him in his choice. Errors exist in the text, e.g. tables not correctly referred to, occasional words left out, and an over use of "etc." was noticed by this reviewer. To the newcomer in water relations work, "etc." is not a satisfactory word to use. In a number of cases where it is used it is not necessary, while in others the factors included loosely under this word would be better spelled out.
S.T. WILLATT
(Melbourne, Vic., Australia)
AGRICULTURAL
SYSTEMS: A N E W I N T E R N A T I O N A L
SCIENTIFIC J O U R N A L .
Agricultural Systems. An International Journal. C.R.W. Spedding (Editor-inChief). Applied Scientific Publishers, Barking, Essex, Quarterly, one volume per year, approx. 320 pp., £15.00 (Postage included).
250
Agricultural Systems will provide a focal point for the exchange of information between the fields of relevant management, economics and social science on the one hand and the essential underlying biology on the other for the purpose of understanding whole agricultural systems and their constituent parts. It will be concerned with the problems of systems both in the underdeveloped countries and in more highly developed agricultures. The scope of the journal will cover a wide range of systems, environments, levels of detail, practical problems and theoretical techniques. The contents of Vol. 1 deal with information for the individual farmer as well as on systems research. In the former category, three papers are incorporated, viz.: "Management information systems for the individual farm firm" by M.J. Blackie (New Zealand), "Deferred grazing of Mediterranean annual pasture for increased winter sheep production" by R.C.G. Smith (Australia) and W.A. Williams (U.S.A.), and "CORNMOD, a dynamic simulator of corn production" by C.H. Baker and R.D. Horrocks (U.S.A.). Two papers deal with systems research. In "The economics of systems research" by J.D. Dillon (Australia), three broad aspects of systems research are discussed, viz. the conjecture that the systems approach constitutes a technolo~gical change in our mode of thinking about the world, the use of the systems approach as a framework for the selection of research programmes and the efficiency of conducting research on a systems basis. "Experimentation in agricultural systems" by C.R.W. Spedding and N.R. Brockington (Great Britain) deals with the kinds of experimentation involved in the study of agricultural systems, mathematical models that are used and the role of field experiments.
NIENKE DE JONG
(Amsterdam, The Netherlands)
water when considering the availability of water in soil. Some techniques for measuring soil-water content and soil-water potential are then mentioned. The remainder of the chapter discusses the determination of water potential, water absorption and xylem sap exudation from roots. These sections are well illustrated with diagrams of the equipment. Chapter 4 moves onto the next stage in the process of water movement in the soil--plant--atmosphere continuum by discussing liquid water movement and'methods for measuring this liquid movement in the plant using three headings, hydraulic conductivity (velocity under unit pressure gradient) of cytoplasm, cell membrane, and parenchymatous tissue, velocity of water movement in the xylem and volume flux of water in xylem vessels. The techniques for velocity and volume flux discussed, however, apply only to the measurements of these values in trees. The final chapter (5) deals with water exchange between the plant and atmosphere. After a brief introduction to the general factors important in the water exchange process, i.e. energy balance of the plant surface, water potential gradient and flux resistance, methods for determining these factors are outlined. These include measurements of air humidity, water absorption by the aerial plant parts, transpiration, stomata and guttation. A summary is given of methods for measuring stomatal aperture and concludes the chapter. This book, as with all books which deal with techniques, is a welcome addition to literature and will be of considerable help to those wanting to find out how to make measurements in plant--water relations work. However, some of the techniques which are discussed at length are not necessarily the best to use for a particular measurement, e.g., the resistance block method of measuring soil moisture is discussed at length (over 10 pages) while tensiometers, which are more reliable in the wet range of soil water, are given less space. The reader should, therefore, be cautious when searching for techniques although the equipment lists and summaries offered will help him in his choice. Errors exist in the text, e.g. tables not correctly referred to, occasional words left out, and an over use of "etc." was noticed by this reviewer. To the newcomer in water relations work, "etc." is not a satisfactory word to use. In a number of cases where it is used it is not necessary, while in others the factors included loosely under this word would be better spelled out.
S.T. WILLATT
(Melbourne, Vic., Australia)
AGRICULTURAL
SYSTEMS: A N E W I N T E R N A T I O N A L
SCIENTIFIC J O U R N A L .
Agricultural Systems. An International Journal. C.R.W. Spedding (Editor-inChief). Applied Scientific Publishers, Barking, Essex, Quarterly, one volume per year, approx. 320 pp., £15.00 (Postage included).
250
Agricultural Systems will provide a focal point for the exchange of information between the fields of relevant management, economics and social science on the one hand and the essential underlying biology on the other for the purpose of understanding whole agricultural systems and their constituent parts. It will be concerned with the problems of systems both in the underdeveloped countries and in more highly developed agricultures. The scope of the journal will cover a wide range of systems, environments, levels of detail, practical problems and theoretical techniques. The contents of Vol. 1 deal with information for the individual farmer as well as on systems research. In the former category, three papers are incorporated, viz.: "Management information systems for the individual farm firm" by M.J. Blackie (New Zealand), "Deferred grazing of Mediterranean annual pasture for increased winter sheep production" by R.C.G. Smith (Australia) and W.A. Williams (U.S.A.), and "CORNMOD, a dynamic simulator of corn production" by C.H. Baker and R.D. Horrocks (U.S.A.). Two papers deal with systems research. In "The economics of systems research" by J.D. Dillon (Australia), three broad aspects of systems research are discussed, viz. the conjecture that the systems approach constitutes a technolo~gical change in our mode of thinking about the world, the use of the systems approach as a framework for the selection of research programmes and the efficiency of conducting research on a systems basis. "Experimentation in agricultural systems" by C.R.W. Spedding and N.R. Brockington (Great Britain) deals with the kinds of experimentation involved in the study of agricultural systems, mathematical models that are used and the role of field experiments.
NIENKE DE JONG
(Amsterdam, The Netherlands)