ORGANIC PHOSPHORUS FRACTIONS IN SOILS OF PANAMA.

Abstract

With the purpose of determining the bioavailability of the organic phosphorus fractions present in different taxonomic classes, it was carried out a study in soil samples which represent important agricultural areas of Panama. It was used 10 soils belonging to ultisols, mollisols, inceptisol, alfisols and andisols order. It was carried out sequential extractions with NaHCO₃ 0.5 M; H₂SO₄ 1.0 M and NaOH 0.5 M to obtain organic phosphorus fractions such as “labil”, moderate “labil” and moderate resistance, respectively. The analysis was conducted at IDIAP Soil Laboratory in Divisa. A completely randomized block design with four repetitions was utilized. The extracted organic phosphorus content was very variable with an average of 37.3 mg/kg of the 10 soils. However, in soils with high degree of intemperism, the organic phosphorus fraction “labil” was the most important, showing that in these soils organic fraction represents the most important nutrient reserve that contribute to increase its fertility. It was observed positive correlation and significant among total organic phosphorus fractions and total phosphorus (0.70); “labil” organic phosphorus and “labil” total phosphorus (0.53); organic carbon and “labil” organic phosphorus (0.40). It was recommended carry out field trials to verify the organic phosphorus performance at medium and long term and the effect of handling on its transformations.