Agricultural Technology and the Margin of Cultivation in the Fourteenth Century
DvETAILED examples of later medieval agricultural technology are not so numerous that the heart sinks at the prospect of a new one. The whole topic of later medieval practice is only now beginning to be systematically explored by contributors to the Cambridge Agrarian History of England and Wales, the relevant volume of which is currently being prepared under the editorship of Dr Miller. The main objection to a single case study, such as the present one, is nevertheless easy to anticipate. It is the inevitable objection to all minute research in agrarian history-that the multiplication of differently observed examples of different ways of cultivating different crops on different soils at different times by different types of farmer makes for painful reading without making generalizations any easier to form, and indeed usually rendering them more difficult. My defence for drawing attention to the present example would be that it implies a set of general technical considerations. It illustrates a pattern of events which -may have repeated itself in many places and on many different types of soil, if I have explained it correctly. The interpretation is grounded partly in principles of agriculture (the principles of crop rotation), partly in principles of economic theory (especially the principle of diminishing returns) and partly in a well-established proposition concerning later medieval economic history (that the production of cereals was declining as a consequence of declining population). This is quite sufficient to suggest its general relevance, and my hope is that it will prove useful in accounting for similar changes in other places. I The problem concerns the relationship between the annual output of cereals, the productivity of labour in agriculture and the technique of production adopted. According to a well-known supposition about the progress of agriculture, with a given range of soils and a given range of techniques labour is likely to be concentrated first on more fertile soils and to be applied to increasingly less fertile soils as the demand for grain increases. Prof. Postan has argued that the margin of cultivation was being extended in this way during the twelfth and thirteenth centuries and that the marginal product of labour was declining through this period. He has argued, too, that the technology of arable farming was linked to that of pasture farming by the use of animal dung as a manure. The expansion of the arable area at the expense of the pasture area would reduce the number of animals which could be kept, and so cause an absolute reduction in the amount of manure available.'