Available Potassium

For information about potassium in soil and its importance to plants click here.

Potassium is extracted from the soil by shaking a 1-gram scoop of air-dried soil for 5 minutes with 10 milliliters of (pH7) 1 N ammonium acetate (NH₄OAc). Plant-available potassium is measured by analyzing the filtered extract on an atomic absorption spectrometer set on emission mode at 766.5 nm. The results are reported as parts per million (ppm) of potassium (K) in the soil.