Depth distribution of fertilizer P and K in two Belgian loamy soil profiles of different origin

Contents of both total and extractable P and K throughout the profile are determined in two experimental fields with loamy texture and long lasting P and K fertilizers history. It is shown that, irrespective of the P treatment, the P administrated as fertilizer is immobilized in the 0-25 cm top layer. Accumulation of K in the arable layer is due to the presence of swelling clay minerals. In the absence of the latter, vertical migration of K is occuring.