Well it depends on what is your definition of ``available Se``.

If you want only (water) soluble Se, extract your soil with water and analyze Se concentration in extracted water using ICP-MS or whatever instrument you have.

If you want exchangeable Se, extract your soil with any phosphate containing extractant such as sodium phosphate and analyze your extractant for Se concentration.

Hello Hassan, see also the methods in the following paper: DOI 10.1007/s10705-007-9109-3 for plant availability of inorganic and organic selenium.

Dear Javed and Martin,

thanks a lot!

or you can try Sequential extraction procedure by tessier 1979 or BCR (modified one). i think yoiu it gives you more information about mobility of Se in soil

Tessier A,Campbell P G C,Bisson M. Sequential extraction procedure for the speciation of particulate trace metals [J].Analytical Chemistry,1979,51(7):844-850.

An analytical procedure involving Sequential chemical extractions has been developed for the partitioning of Particulate trace metals (Cd, Co, Cu, Ni, Pb, Zn, Fe, and Mn) into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual.

There were no discussions about Se.

Good discussion

ICP-MS