Mehlich 3 or Olsen extractants for P at soil pH above 7?

Questions sometime come up about specific extraction methods for soil phosphorus (P). In general, the Bray 2 extractant is often used for soils that have a medium to low pH (nuetral to acidic), the Olsen extractant is often used on soils that tend to have a high pH (alkaline), and the Mehlich 3 extractant is used across a wide range of soils.

Each extraction method will remove a different quantity of soil P. We have calculated an MLSN minimum for…