Question

An experiment involving the use of flame photometry to determine the 'available' potassium in soil samples was done and the potassium was extracted using a 0.5 M ammonium acetate/acetic acid solution. Why was ammonium acetate/acetic acid solution used and not water? Thoroughly explain the reason.

Answer 1

Soils contains large amounts of potassium but only a small parts usually less than 1% of the total potassium is in exchangeable form and much smaller amounts are in soil solution. Most of the potassium in the soil is present in the non exchangeable forms.

The term "available" potassium incorporates both exchangeable and water soluble forms of the nutrient in soil.The benefit of using ammonium acetate acid solution for extraction is because the NH4⁺ ion provides a sharp rapid separation of potassium from exchange complex.It has also been observed that more the quantity of Ammonium acetate more is separation efficiency for a given sample.