Comparison of Chilean Natural Phosphatic Minerals

The begining of phosphatic deposits study was dated around 1963 through the survey developed at Bahia Tongoy, and later on at Pachingo in 1989. In this article, a synthesis of the main geological, physico-chemical, and agronomic features of these materials is presented, remarking some of these properties, and agronomical applications obtained after the accomplished research. Location of deposits is described, as well as their origin and phosphorus enrichment. Some solubility results of Chilean rocks is compared with other reactive rocks of USA, and Latinoamerica. Results of classical rock composition, is compared with some Chilean rocks, located at the north region of Chilean territory. Actualized figures of phosphate rock production at Chilean market, is also presented in this paper. Major conclusions obtained through field research in Andisols, show that these national phosphate rocks have an important fertilizer potential. The most remarkable phosphorus content and high reactivity was Bahia Inglesa rock; Mejillones showed similar efficiency to Tampa rock when it was employed as concentrated material. Vegetable species of major efficiency in the uptake of available P from these sources, were those of longer vegetative period, such as grass, and high P uptake as lupins or rape seeds, and also flooded rice. Palabras Claves : minerales fosfáticos, reactividad de las rocas, Andosoles, uso agronómico. Comparison of natural phosphatic minerals, Carlos Rojas. 29