Variation in phosphates activity in soil : a case study

الملخص EN

Alkaline phosphomonoesterase (PME) and phosphodiesterase (PDE) activities were measured in the surface layer (0-25 cm deep) of soils from 26 collection sites.

Soils were sampled from virgin desert, lime (Citrus aurantifolia), alfalfa (Medicago sativa) and date palm (Phoenix dactytifera) producing areas.

The activities of PME and PDE were generally low with means of 11.87 and 4.94 mg p nitrophenol produced g-1 h-1, respectively.

Multiple regression analysis revealed that over 80 % of the variances in PME and PDE activities could be accounted for by the differences in soil physiochemical properties.

Activities of PME and PDE were nearly completely inhibited in soils with salinity (EC 1:5) values over 4 dSm-1.

In general, phosphatase activities were favored in soils with fine textures, relatively high concentrations of organic carbon (C) and low salinity.

Variations in PME and PDE activities were significantly related to variations in concentrations of bicarbonate extractable inorganic phosphorus (P) in soil.