ORGANIC PHOSPHORUS-CONTENT IN SOIL SAMPLE S

The objective of this laboratory investigation was to estimate the tot al organic phosphorus content, and labile organic phosphorus fraction of samples taken from the surface layer of soils of different taxonomi c classes. The study was a completely randomized design with the treat ments consisted of 17 soil samples. The content of total organic phosp horus varied from 7 to 272 mg/kg of soil. The labile organic phosphoru s varied from 6 to 35 mg/kg of soil, being much greater than the labil e inorganic phosphorus, and on average corresponding to 26% of the tot al organic P in the soil. Analysis revealed that total organic P was c orrelated with total P and C in ultisols and total P, Fe2O3 and clay c ontent in oxisols. Thus, for both soil classes, the labile organic P w as intimately related to the available P, indicating the potential con tribution of this fraction to the availability of phosphorus in these soils.