Vertical distribution of phosphate in some sub-humid tropical soils of Bangladesh

Abstract

The distribution of organic, inorganic and total pliosphates and the reasons of their variation in a number of sub-humid tropical soil profiles has been examined- An appreciable amount of phosphate was found in the surface soils but their amounts decreased with depth. Moderate to well drainage caused a gradual decrease in organic phosphate with depth in most of the soils. Inorganic phosphate showed a heterogenous distribution throughout the profiles and generally decreased with depth in profiles with moderate to well drainage capacity, A sharp decrease in organic phosphate but no definite pattern in inorganic value in deeply and shallowly weathered profiles were observed. A gradual decrease in both the values was generally noticed in most of the alluvial soils. Total phosphate in the soils reflected the same trends as was noticed inorganic phosphate distribution. Correlation study suggested that phosphate variation was significantly correlated with organic matter, total nitrogen, pH and clay contents of the soils.