3.5. Available nutrients in the rhizosphere
The concentrations of available N and P in the rhizosphere of maize were
42% and 36% lower, respectively, under the 10-cm than the 30-cm
topsoil depth (P < 0.05, Fig. 5a, b). Topsoil depth did
not affect available K (P > 0.05, Fig. 5c). In
comparison, the concentrations of available N, Olsen P and available K
in the rhizosphere of soybean were 12%, 25% and 19% lower under the
10-cm than the 30-cm topsoil depth, respectively (P <
0.05, Fig. 5a, c). However, there was no difference in concentrations of
available N, P and K between the 30-cm and 20-cm topsoil depths
(P > 0.05, Fig. 5c).