Apatite inclusions have been identified in several primary minerals, and their abundance and morphology have been described. A comparison of several methods used for the determination of total P in soils showed that Na₂CO₃ ...

"Nonextractable" soil inorganic phosphorus can have both a primary and a secondary origin. Apatite included within other minerals and phosphorus distributed throughout mineral lattices constitute the primary sources. ...

A modified version of the phosphate fractionation procedure of Chang and Jackson (1957) included the determination of "residual inorg. P" and introduced a revised nomenclature for the other fractions. Added phosphate sorbed ...