Variation of phosphorus status in soils of Ganges Floodplains, Bangladesh, based on the level of decalcification

Abstract

Phosphorus status of soils derived from calcareous sediments in the Ganges Floodplains, Bangladesh, was evaluated as a function of decalcification. Total P concentration of the soils ranged from 257 to 726 mg kg⁻¹, and inorganic P always predominated over organic P. In inorganic P, the amount and percentage of nonoccluded Ca-bound P (Ca-P) was higher for the decalcified horizons than for the horizons containing free carbonates, although more than half of inorganic P was occupied by occluded-P. Phosphorus availability, assessed by the Bray P-2 method, was high in the decalcified horizons while low in the horizons containing free carbonates, except for the oldest and noncalcareous soil. It was suggested that P availability in the soils of the Ganges Floodplains could be enhanced by decalcification after deposition of sediments.

Key Words:

• Bangladesh
• decalcification
• Ganges Floodplains
• phosphorus status