Hydrogen peroxide or combustion treatment is usually employed to decompose the humus of the soil. We examined the influence of these methods to K-fixation of soils.
When soils are destroyed with H_2O_2, not only the amount of exchangeable potassium, but also the clay fraction of soils increases, as compared with untreated soils.
As soils are combusted at 500℃, the amount of exchangeable potassiurn decreases, and the fraction of coarse sand or fine sand increases, in spte of decreasing of silt or clay fraction.
The amount of fixed potassium increases in proportion to the clay fraction.