Evaluación de dos métodos para la determinación de fósforo asimilable en suelo de tipo andisol

Abstract

The current research evaluated the effectiveness of a method for the estimation of assimilable phosphorus in andisol samples from Cebadas River microbasin belonging to the Development for the Environment and Climate Change Research Group (GIDAC). A total of 145 andisol samples were used by means of (Bray-Kurtz and Olsen) spectrophotometric methodologies, and the method linearity parameters, system linearity, correlation between both methods and normality of the data were evaluated. The results obtained for the soil samples were 4.517 ppm and 0.5370 ppm of phosphorus for the Bray-Kurtz and Olsen methods respectively, the Bray-Kurtz extractant extracted more phosphorus (P) compared to Olsen, these results can be attributed to the fact that the acid solution of Bray-Kurtz promotes the partial dissolution of inorganic colloids, and the extracted forms of P linked to calcium (Ca-P), iron (Fe-P) and aluminum (Al-P). While the values obtained by Olsen's method result from the possible dissolution of organic phosphorus due to the high pH (8.50) of the extractant solution, considering that in acid soils the formation of carbonates is inhibited, which does not allow the release of P from the aforementioned inorganic forms. It was concluded that the most accurate method for determining phosphorus in andisols was the Bray-Kurtz method due to a comparison of the effectiveness and efficiency of the two methods, taking into account the quality requirement determined by the variance percentage and the optimal use of time and resources. Once the method standardization process was completed in the laboratory, it was recommended to use the data obtained in order to perform a permanent monitoring, establishing parameters for its control in future studies carried out by the Research Group.