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Standard operating procedure for soil available phosphorus - Bray I and Bray II method

Copyright licence

Year of publication 2021

Place of publication Rome, Italy ;

Pages 17 p.

Author FAO

Publisher FAO ;

Product type Booklet

Category Corporate general interest

Edition 1

Synopsis (short abstract) P-Bray 1 and P-Bray 2 methods are normally limited to acid soils with water pH values less than 6.8. The P-Bray 1 Method removes a fraction of the “adsorbed” phosphorus (Al-P, Fe-P, Mn-P and Ca-P but less efficient) while the P-Bray 2 Method is best suited to acid soils where rock phosphate has been the primary P fertilizer source and/or the major portion of P exists in the soil in various forms of calcium phosphate. Bray extractants should not be used on alkaline soils because the acid tends to be neutralized and/or excessive calcium phosphates may be extracted, giving a false high test for available P.

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