Phosphorus Transformations During Plant Decomposition

Abstract

During decomposition, microbial organic P is rapidly formed from plant inorganic P. With young plant material, much of the microbial P is dephos-phorylated and becomes inorganic P. With mature material little organic P occurs even after three months' decomposition. This is associated with a less decomposable substrate and with the maintenance of a viable population. Plants generally contain sufficient inorganic P for bacterial requirements during decomposition. During dephosphory-lation of microbial organic P, acid-labile forms are first involved and then the acid-stable forms. Secondary decomposition possibly involving dead micro-organisms results in the resynthesis of both forms; these suffer further dephosphorylation and the residual products consist roughly of 70%3 acid-labile and 30 % acid-stable P. With mature material the amount of organic P remains fairly constant during five weeks' decomposition and consists of equal parts of both forms. Enzyme systems converting acid-stable and acid-labile forms to inorganic P, and acid-stable to acid-labile forms, could be distinguished. -From author's summary.