To a large extent, soil mineralogy also greatly affects soil K
equilibrium and fixation. Soil mineralogy significantly influences
cation exchange capacity and K saturation of the exchange complex
(Goulding, 1983). This means that soils of differing mineralogy have
starkly different K buffering capacities. Also, K in solution tends to
be in equilibrium with available K, which tends to be in equilibrium
with nonexchangeable K (Beckett, 1964). Therefore, K fixation, or
conversion from available K to nonexchangeable K, maintains the
K status of soils by reducing leaching and luxury consumption, but
also reduces the short-term effectiveness of K fertilizer application
because as available K increases, equilibrium moves toward
nonexchangeable pools.