Анотация: The purpose of this research is to determine the phosphorus amount of soils of Tekirdag province that have different chemical and physical properties according to the Neubauer method which is selected as a biological method and to select the method which gives highest relationship from the 3 different chemical extraction methods for determining the available phosphorus amount. For this purpose 26 samples of soil are collected from 0-20 cmТs depth in Tekirdag.. - The greenhouse study has been performed in accordance to the Neubauer seedling method and coincidence pattern with 3 repetitions. The rye (Secale cerale L.) has been selected as the test plant.. - In order to determine the most suitable chemical method as related to dried matter yield, phosphorus content and total phosphorus uptake of the test plant has been taken as the biological (standard) criterion.. - No relationship has been found between any of the chemical extraction methods and dry matter yield of rye plant in this study.. - According to the research results, significant relationships have been found only with the water soluble phosphorus method and phosphorus content and total phosphorus uptake of the test plant (respectively r= 0.374*, r= 0.342*)