Evaluation of phosphorus in fertilizers with 2% citric acid solution: extraction techniques

Abstract

In this paper was studied the behavior of the 2%citric acid solution for phosphorus evaluation in simple fertilizers and mixtures in two extraction conditions: directly in the sample and, therefore,, in presence of water soluble components, and after the extration of water soluble components, that is to say the same classic extraction technique adopted for ammonium citrate solution. The results were compared among themselves and with those attained by water and ammonium citrate criteria making possible to conclude that the direct citric (ratio 1:100) is affect by the presence of water soluble components; also, the water insoluble fraction of the simple fertilizers presents greater solubility in ammonium citrate solution the water insoluble fraction of the fertilizer mixtures containig rock phosphates presented greater solubility int the citric solution with extraction after the elimination water soluble components and the smaller solubilities were presented in the citric solution with direct extration by the mixture containning hyperphosphate but in the ammonium citrate solution by he mixture containning Araxá apatite. The mixture containning degelatined bones meal presented the same solubility in three extraction techinique studied.