Modelling decision-making processes for annual crop management

Oil-farm technical management of annual crops is a recurrent task, so farmers can to a large extent plan their cropping operations. Taking winter wheat on arable farms in one part of France as an example, this planning is represented in a conceptual model consisting of a set of descriptive variables and decision-making rules. Six descriptive variables and five types of decision-making rule have been identified. Three of the variables describe the intended timing of cropping operations, one determines the possible modes of operation and one groups the fields sown to wheat into sets so that different management modes can be applied to each set. We demonstrate that this model accounts for the kinds of planning practised by the farmers in our survey: taking 3 successive years' wheat crops on these farms, with sharp year-to-year differences in weather patterns, we show that planning largely determines the technical management actually exercised. The model proposed enables one to classify and understand the observed variability in farmers' practices, putting the weather in its place among other factors. This representation of decision-making processes in the form of a 'model for action' has been validated on wheat in other parts of France and is currently being validated for other annual crops. (C) 1997 Published by Elsevier Science Ltd.