Simulation of Nitrogen Behavior in Soils

344 suggests. The reviewer has a great sympathy with the authors who might hope that a large number of experiments in the world who are working mostly in collecting and measuring a huge number of natural rock samples, would sometimes come back to their library to think deeply over the physical principles of rock magnetism through this book. Takesi Nagata, Tokyo NITROGEN MODELLING J. Beak and M.J. Frissel, 1973.Simulation of Nitrogen Behavior in Soils. Centre for Agricultural Publishing and Documentation, Wageningen, 67 pp., Dfl. 13.00.

lating complex problems. For readers uninitiated in CSMP the authors provide some explanations, but perhaps one should also consult references such as the IBM Application Program (Y20-0111-0), System/360 CSMP (360A-CX-16X) Systems Manual. For a full understanding of the physical processes modeled, i.e., water, heat, and solute movement, consult "Simulation of Transport Processes in Soils", a monograph by C.T. de Wit and H. van Keulen (1972). It is summarized in Chapter 4 of this monograph. This book is singularly lacking in mathematical expressions, with one exception. Flux of water in the vertical direction is defined by the following diffei'ential equa° tion: de

v=D-~ +K The authors present this simulation monograph to summarize progress in nitrogen modeling at their institution, to promote an exchange of ideas about the particular type of modeling language and technique used (CSMP/360), and to let experimenters know what kinds of experiments should be carried out to provide modelers with necessary data. The 67 pages comprise of five chapters and an Appendix (full reproduction of ~ the CSMP sou rce list, 12 pp.). Chapter 1 describes the general nature of the nitrogen problem attacked, the nitrogen transformations simulated, and the compartment technique for simulating transport processes. This proposed model of nitrogen behavior in soils is by no means complete. It attempts to consider mineralization of organic matter, immobilization or assimilation, nitri~ fication, flow of heat and water, and nitrate transport. The model assumes that the soil has a high buffer capacity and is under "aerobic" conditions. It does not consider denitrification, nitrogen fixation, pH effects, or crop water and nitrate extractions. Much more work will be needed to simulate the real world. Chapters 2 and 3 are brief narratives on the basic processes involved, flow charts describing simulated processes, definition of the simulated process in CSMP language, and approximations for input variables. The computer modeling language is the Continuous Systems Modeling Program (CSMP/360), a versatile language for simu-

and the corresponding CSMP version is: FLRW(I) = AVDIF(I)*(WC(I°I) -- (WC(I))/ TCOM (I) + AVCON D(I) where I and I-1 are continguous soil compartments (layers). Throughout this monograph one has to translate this kind of CSM P version to conventional mathematical expression that one is more familiar with. Chapter 5 presents the results for a 45-day simulation period with 7.5 cm of irrigation water applied on the 6th day, including data for soil water, soil temperature, soil organic matter composition, microbial biomass, and nitrate and ammonium contents as a function of both time and soil depth. Thecomputer time to simulate 1 day for a 10-compartment (layer) case is reported to be about 0.25 min. This overall model has not been verified because experimental data are lacking. Although oriented toward computer simulation modeling, this book contains a wealth of information on nitrogen transformations and water, solute, and heat flows. In other words, a non-modeler can gain quantitative insight on pertinent mechanisms and processes in the soil-water system without fully understanding the CSMP program. Modeling nitrogen transformations and transport is a timely topic. It has bean of environmental interest because of increased awareness of nitrate pollution of surface and ground waters. Moreover, the energy crisis

345 and consequent shortage of nitrogen fertilizers have made it an even more important agronomic problem. This soft-cover simulation monograph is recommended to scientists and engineers interested in terrestrial nitrogen problems. K.K. Tanji, Davis, Calif.

CHLORINITY/SALINITY William J. Wallace (Editor), 1973. TheDevelopment o f the Chlorinity/Sa/inity Concept in Oceanography. Oceanography Series, 7. Elsevier, Amsterdam, xii + 227 pp., Dfl. 46.000

Perhaps the reaction of many oceanographers to the title of this book will be one of wonder that anyone can find sufficient material to fill a book on the subject, contentious though it has been at times. The idea that the total dissolved salts (salinity) in seawater can be estimated from a determination of a single constituent (chlorinity) has undoubtedly proved to be most useful to oceanographers. It is based on the concept that the composition of sea-water is constant (or almost constant) throughout the major oceans. In this book Dr. Wallace painstakingly describes how studies of the composition of sea-water developed until they were put to some practical use by Knudsen at the beginning of the present century. The ancient views on the nature of salt, the vague and unreproducible experiments of Aristotle and the prodigious writing of Pliny (here credited with the first quantitative estimate of the amount of salt in sea-water)" give the book a start which is a mixture of the irrelevant and the interesting. The way in which sea-water analysis benefitted from techniques developed for the analysis of mineral waters is perhaps the main start to the stow. Some of the famous chemists of the 16th--18th centuries showed an interest in sea-water but the author also brings to light the work of lesser known names. Marcet (1819) was the first to state that the major components of sea-water occurred in constant proportions and his findings were confirmed by the classical works of Forchhammer and Dittmar, both of whom, however, admitted to finding varia-

tions which they could not explain. Having presented the evidence available at the end of ~he 19th century the author then describes the work of Knudsen et al. on which the famous salinity/chlorinity equation and the Hydrographical Tables were based. In the concluding chapter (13pp) he airs most of the arguments against and criticisms of the salinity/chlorinity relationship and related topics which have been made in recent years, and he discusses the new definitions of salinity. By this ~tage the salinity/chlorinity relationship has taken a beating and its limitations are obvious when one is seeking the third decimal place in saliniw or sigma-t. It is not yet dispensable, however, because the new definition of salinity in terms of conductivity still contains such a relationship. The book is very well presented and contains few errors. There are two factual statements which require correction, "however. On p.158 the 1940 Knudson and Jacobsen definition of chlorinity is described as being in use "until recently", which is misleading as this definition has not been rescinded. On p.160, in the discussion of the new recommended relationship between salinity and chlorinity the difference quoted should be 0.0026%a,, not 0.026%e (the official recommendations of the new definition was published in four oceanographic journals and the author has, unfortunately, quoted from the one journal which contained a misprint). Apart from these points, I enjoyed reading the book and would certainly recommend it to those interested in the history of marine chemistry. J. Culkin, Godalming

BARRIER ISLANDS M.L. Schwartz, 1973L Barrier Island¢ Benchmark Papers in Geology, Vol. 9. Dowden, Hutchinson and Ross, Stroudsburg, Pa., 451 pp., £ 11.00,

To edit is to prepare for publication -- by selection, arrangement and annotation. "Barrier Islands", edited by Maurice L. Schwartz is a representative example of editing at its best. The book, Volume 9 of the Benchmark