Conclusion:
Due to population growth and the associated agricultural developments and upland soil erosion, western rivers discharging in Urmia Lake release massive quantities of P-loaded water and sediment. This is the main reason for eutrophication of wetlands at this lake. In this investigation, a selection of extraction methods was considered in their capability to extract sediment-bound P. The extracted quantities appeared to vary significantly between these methods, even though most methods showed a good correlation with each other. The extracted P was also compared with algae growth in a bio-assay, for the algaeSelenastrum capricornutum . Correlations with algal growth were modest, except for the Colwell-P that correlated very well. For sediments as discharged into Urmia Lake, where pH and EC appears to have an effect on algae growth, the Colwell-P extraction therefore looks as the best option. Because of dense algal bloom in lower research areas, withholding fertilizer application for building up crop requirement is recommended in susceptible land for erosion.