Which method is primarily used to measure phosphorus in acid soils?

The Mehlich Test is the correct method primarily used to measure phosphorus in acid soils. This test employs a multi-nutrient extraction solution that is effective in extracting phosphorus, along with other nutrients, from the soil. Its formulation is tailored to work well in acidic environments, where phosphorus availability can be affected by the soil's chemical properties.

While the Bray Test is also used for phosphorus measurement, it is specifically designed for soils that are either neutral or slightly acidic, thus making it less effective in highly acidic soils. The Olsen Test, on the other hand, primarily applies to alkaline soils and is not suitable for acid soils. Soil Phosphate Analysis, being a general term, encompasses various methods and can lack specificity. Hence, the Mehlich Test is preferred for accurately assessing phosphorus levels in acid soils, ensuring that correct soil management practices can be applied based on those results.