Fig. 6. X-ray diffraction (XRD) patterns of the rhizosphere phlogopite at different levels of external K supply (from P0 to P2). The XRD pattern of bulk phlogopite as observed in the different treatments is presented for comparison. The intensity ratio of the 1.4- to 1.0-nm reflection (I1.4/I1.0) for rhizosphere phlogopite are 0.00 in P2, 0.15 in P0.4, 0.26 in P0.1, 0.33 in P0.05, and 0.30 in P0.