DeciBle, a software package for wheat crop management simulation

DeciBle is a simulation tool intended to support the design and evaluation of technical management for the wheat crop. Crop management is here considered from a strategic planning point of view, as the choice of technical decision rules for the whole growing period rather than day-by-day decisions for each operation. DeciBle simulates the consequences for technical operations and crop production of a set of decision rules over a wide range of possible contexts (regions, year-to-year weather variation, fields, etc.). It is a simulation in which two models interact: a decision and a crop model. The decision model represents the decision rules through a specific formalisation and generates the operations for each context. The crop model is a set of modules simulating plant development, crop environment and yield accumulation implied by these operations in this context through the generation of loss functions or risk estimates. The crop model consists of a set of empirical models based on agronomic diagnosis and experimental references widely used in France. A general validation of DeciBle is carried out using observed data from a network of field trials. The wheat development stages are simulated within 4 days of the observed dates in more than 80% of the cases and the yield components and final yield with differences of less than 15% from the real values in more than 75% of the cases. We discuss (i) the causes of unsatisfactory predictions and the prospects for improving the various modules of the crop model; (ii) the use of the simulator in some decision problems; and (iii) the position of DeciBle among the existing models for crop management decision help, emphasising the originality of the method of decision representation. (C) 2004 Elsevier Ltd. All rights reserved.