BOOK REVIEWS 77

This is a realistic background to a study of this kind and gives the book a very practical flavour.

The book is well produced and well illustrated with 59 tables, 44 figures and 32 plates, many of them in colour: it is easy to read and contains few printing errors.

C. R. W. SPEDDING

Duckham, A. N., Jones, J. G. W. and Roberts, E. H. (Eds). Food Production and Consumption: The l~[ficiency of Human Food Chains and Nutrient Cycles, North Holland Publishing Co., Amsterdam, The Netherlands. Price: SUS 48-95.

This book is an attempt to measure or estimate the world's potential for producing human food, that portion of this potential which is currently realised and those interfaces in the overall process---from the receipt of solar radiation on a land surface to the ingestion of food by man--which seem open to manipulation. The general conclusion reached is that the greatest potential for the improvement of world food production lies in the area of conventional agricultural technology.

The construction of an analysis of this nature must have occasioned thc editors much thought. Their solution is sensible; they themselves have written the first chapter, which sets the problem in perspective and defines terms, whilst the twenty-ninth and last chapter, written in the light of the intervening twenty-seven chapters, provides an integration. These intervening chapters are contributions by invited authors, each expected to deal with one succinct aspect. They commence with an analysis of the growth of world population and of incomes, so to estimate current world food demand, together with estimates of the past rate of growth of food production. This chapter, by W. H. Pawley, formerly of FAO, leans heavily on the predictions made in 1970 by FAO in the Indicative World Plan, but suggests a required annual rate of growth in food production in the developing regions of 3.3°.'0 per annum--considerably lower than the estimate of 4'3o made by the UN in its Second Development Decade projections. A doubt is cast not so much on the technical possibility of such growth as--because of social at:d economic difficulties and lack of political will to remove t hem - -on the likelihood of achieving it.

The second section deals with the basic resources of agriculture and their complex interrelations from an ecological point of view. The canvas is still broad and, understandably, some small errors of fact have crept in as authors have moved into disciplines not their own; ruminants, for example, do not excrete nirogen gas! In addition, as is again understandable, some repetition of arguments given earlier occurs. The third section deals with photosynthesis in three chapters, moving, with some overlap, from the chloroplast to the whole plant and then to the crop. A further chapter deals with protein production by the green plant. The secondary use of plant products by animals is then analysed to show the low efficiency with which animals convert energy in their diets to energy man can

78 BOOK REVIEWS

consume. A word of warning is inserted hcrc by C. C. Balch and J. T. Reid when they remark on the extreme vulncrability of overall estimates of efficiency to inaccurate measures of partial quantities. Human nutrient needs, food storage, industrial food production and food habits are dealt with, as are ways of dealing with agricultural wastes and the effects of industrial and other products that pollute land and reduce productivity. Finally, an account is given of the dependence of agriculture and food systems on support energy, mostly derived from fossil fuels.

The tinal section deals with social and economic constraints on the management of the chain of biological events in the production of food and the factors involved in making decisions by both the farmer and government agencies. It commences with an account of systems research which hardly seems relevant since it concludes that 'human food chains and nutrient cycles are so complicated in practice that it is unlikely that more than a few limited areas could be satisfactorily modelled'. In a following chapter operations research is equally regarded as having had little impact on the management of farms although it is thought likely to do so in future. A thoughtful chapter by Duckham indeed closes on the note: 'We need to accelerate change but we do not know enough about ways to achieve it'.

This is a brave at tempt at a synthesis and the editors are to be congratulated for daring to make it. The biological components of the energy and material transfers involved are dealt with thoroughly, although perhaps the term efficiency is used in too many different ways to describe them. The book is well produced, expensive and takes a nice long time to read. The accretion of errors by multiplying efficiency terms, referred to earlier, is not of great moment when the objective is to point out the great magnitude of the inefficiency with which solar energy is converted to food and to draw attention to ways in which modern knowledge might be used to reduce inefficiency if we did but know how.

K. L. BLAXTER