Book reviews 77

Agriculture and environmental change

Agriculture and environmental change, A.M. Man- nion, Wiley, Chichester, 1995, £17.99, ISBN 0471954780.

This is a very good book for Australians inter- ested in agriculture to read because it says very little about Australia. Dr Mannion takes a global and historical view of agriculture and environmental change and thus gives much weight to more popu- lous and longer settled lands than ours. The book begins by viewing agriculture as a modified ecosys- tem and discussing the domestication of the major crop plants (wheat, barley, rice, maize, potato and cotton) and animals. As these domestications took place at least 7000-10000 years ago, both plants and animals had been highly modified by breeding long before Australia was settled. Also, the conti- nent's geographical separation since the rise of sea level after the last glaciation meant that there had been no diffusion of agriculture before European occupation. We are therefore even more aberrant in world terms than the 'New World' of the Americas. These had an injection of European agricultural tech- nology and crops from the 16th century onwards, but also already had agricultural landscapes of their own from which crops such as potato and maize were introduced to Europe.

The historical review deals with the development of agriculture in the Near East and then with changes in Europe and China and after AD 1500, the Ameri- cas and Russia. It is a necessarily brief account, looking at four periods--up to AD 500, AD 500- 1 500, 1 500-1 914 and since 1 914. Contrasts and parallels between the periods and places are empha- sised. For example, it is noted that New World crops such as maize, peanuts and sweet potato arrived in China at much the same time as they were intro- duced to Europe. Perhaps the most disappointing part of this review, for me, was that the discussion of the Near East ended with a comment that "society col- lapsed as it was unable to adapt to rapid climatic change. Are there parallels here with likely global warming of the early twenty-first century?" (p. 67) Given the well-known salinisation and related envi- ronmental problems of the Tigris-Euphrates valleys at this time, this remark seems a simplistic throw-

away line. Thus it was unsatisfying that the region was ignored in the later parts of the chapter.

The book then changes focus, with four chapters dealing with types of agriculture--transitory systems (nomadic pastoralism and shifting cultivation), set- tled arable systems, settled pastoral systems and settled mixed farming systems. Geographical con- trasts are again emphasised, but historical detail is replaced by pleasingly up-to-date information on land use, production and energy flows within the different systems. In discussing nomadic pastoralism, Dr Mannion comments that "while such systems may appear fragile they are really stable systems within a fragile environment" (p. 107). The fragility of the physical environment and the permanence of disrup- tions to it, are themes with which Australian re- searchers can readily empathise.

Case studies are used extensively to illustrate the details of differing agricultural practices. For exam- ple sorghum is grown in arable systems in Central America either as monoculture for animal feed, or as a subsistence crop with maize and beans; while in Egypt, it is part of a summer crop with cotton and maize, grown on freehold land but with government-controlled irrigation. A quick turn to the useful index shows that it is part of mixed farming systems, with millet as a co-crop, in western Africa. Australian readers will be surprised by some of the comments about this country--for example, that "the predominant species [of beef cattle for export] is the droughtmaster" (p. 172) and that there is "extensive ranching" of sheep in the Northern Territory (p. 179). By neglecting to mention the southern half of the continent, the comments imply that most live- stock production in Australia occurs in the north, which is clearly incorrect.

The chapters on environmental aspects change focus yet again. One chapter deals with impacts in "middle and high latitudes, which correspond mainly with the developed world," and the next with im- pacts in "low latitudes, which correspond mainly with the developing world" (p. 227). I found this third change of focus irritating, particularly because it is overly generalised. For example, the severe erosion of the loess plateau of China is discussed in the chapter on low latitudes; and as Dr Mannion comments, the low latitude part of Australia is dis- cussed in the chapter on middle and high latitudes

78 Book reviews

because it in the developed world. Indeed the book loses some of its global focus in this section. For example, the discussion of loss of biodiversity is very heavily UK-biased. Again Australian readers would be surprised at the implication that the major threat to our wetlands is flooding of those in the lower Murray basin "with saline water derived from upstream irrigation systems," (p. 232) and at the statement that soil erosion in the developed world has only been acknowledged since the 1970s (p. 237). Other irritations were that salinisation was discussed in relation to irrigation but not dryland salinisation and that the role of phosphorus as well as nitrogen in eutrophication was largely ignored. However the chapter covers most of the major im- pacts, giving clear accounts of the processes in- volved and recent data on severity.

The maps in the book are clear and readable, although sometimes they are incomplete. For exam- ple, Figs. 4.2 and 7.7 do not show all the locations mentioned in the accompanying texts. I find gener- alised maps such as Fig. 9.5 showing world desertifi-

cation misleading. In the text the difficulty of con- structing such maps from disparate information is discussed, but frankly what is the use of a map showing most of the existing natural desert areas of Australia as being at moderate to high risk of deserti- fication?

The book is densely written, with a high informa- tion content. It is not just a collation of facts; the material in each section is cross-linked and explained in terms of both physical and socioeconomic factors; and there is a challenging breadth of material and concept. I cannot imagine most undergraduates sit- ting down to read it in detail, but I return to my starting point. Because of its global and historical scope, it is an interesting and helpful book for those of us interested in agriculture.

Ann Young School of Geosciences

University of Wollongong Wollongong

Australia