Name the methods for extracting phosphorous
Phosphorus/phosphate - Phosphorous is estimated as phosphate. Some methods for extracting phosphorous are as follows:
Dyer method : 1% Citric acid used for extracting available soil phosphate .
Bray and Kurtz method : Phosphate is extracted with a solution of 0.03M NH4F in 0.025M HCl and 0.5M NaHCO3 and solution adjusted to pH 8.5 .
Olsen's method : Phosphate is extracted with 0.5M NaHCO3 adjusted to pH 8.5 with 10% caustic soda.
The extracted phosphate develops colour when treated with ammonium molybdate and stannous chloride. The colour intensity is measured with the help of a colorimeter.