How to do a Fizz Test

  • Put two tablespoons (30 ml) of dry soil in a clean, dry bowl.
  • Add a tablespoon (15 ml) of white vinegar (5% acetic acid).
  • Listen carefully.

The amount of fizz is roughly proportional to the amount of carbonate in the soil. If you have put your ear right by the soil in order to hear anything (and you have normal hearing), your soil is not fizzy. If you can see bubbles or easily hear fizzing, your soil is fizzy.

If you have fizzy soil, you should get an AA8.2 soil test rather than the standard Mehlich 3.  With fizzy soils the Mehlich 3 test will overestimate calcium which will give you an inaccurate TCEC.

Fizzy soils are generally due to the presence of free calcium in the soil.  This may be naturally present in your soil if you live in an area with limestone soils.  It may also be present if you have applied ag lime in the last 3 years or gypsum in the last 6 months.