There are several benchmarks or dates for the crisis. The second administration of President Prado (1876-1879) had six Finance Ministers, none of whom lasted a year. Contreras Carranza cites 1873 as marking the crisis. The Dreyfus organisation suspended the payment of guano export revenues to the Peruvian State, because all the money was spent in debt service. Guano exports fell from 575,000 tons in 1869 to less than 350,000 tons in 1873, and the Chincha Islands and other guano islands were depleted or almost depleted. Also, the quality (nitrogen content) of the guano fell. By contrast, saltpeter was increasing its share in the export market: while some 1.7 million tonnes had been shipped from Tarapacá between 1860 and 1870, in the following decade the figure rose to over 4.4 million tonnes.Blackmore, "The Politics of Nitrate in Chile", p 288
