Dynamique et comportements stratégiques sur le marché international du phosphate

The paper studies the dynamic of world phosphate rock prices in relation with market demand and supply balances. The analysis develops the global mechanisms of successive development of market demand and supply balances that are sustained by the strategies of main phosphate rock producers. Cooperation, non-cooperation and predation are the main strategies of the two dominant players, namely OCP (Morocco) and Phosrock (USA) during the period 1960-2000. These strategies are analyzed by 'prisoner dilemma' and 'limit pricing' models. We consider a two-steps game within a duopoly according to Kreps-Scheinkman framework with Cournot and Bertrand duopoly hypothesis. The empirical results reveal the influence of stockpiles fluctuations and phosphate fertilizer price on the world phosphate rock prices.