Short-term Influence of Organic Matter and Saline Water on Inorganic Soil Phosphorus Transformation in Barisal and Dumuria Soil Series of Bangladesh

A laboratory incubation experiment was carried out to investigate the influence of soil salinity and organic matter on inorganic phosphorus transformation with times in two different soil series such as Barisal and Dumuria located in Ganges Tidal Floodplain sites of Bangladesh. Two representative soil samples were collected from surface soil (0-15 cm) with composite sampling. The salinity and organic matter treatments were 4 dS m-1 and 5 t ha-1 (decomposed cow dung) with three replications. The treated soils were then incubated in the laboratory at field capacity moisture condition. To determine the transformation of different forms of inorganic P, sampling was done for 0, 7, 15 and 30 days. Different forms of inorganic P such as soluble and exchangeable phosphorus (SE-P), iron and aluminium bound phosphorus (Fe and Al-P), calcium bound phosphorus (Ca-P) and residual phosphorus (RE-P) were determined at different days of incubation. For Barisal soil series, the sequence of different forms of inorganic P was Ca-P>RE-P>Fe and Al-P>SE-P according to their amount. For Dumuria soil series, the sequence was Ca-P>RE-P>Fe and Al-P>SE-P, respectively. The sequence clearly indicates that the soluble and exchangeable P increases with time due to a combination of salinity and decomposed organic matter which increases the uptake of P and ultimately increases the yield. The changes were statistically significant (P < 0.001) in the case of all three soils.