Captions
Fig. 1. Effect of topsoil depth on grain yields of maize and
soybean in 2016, 2017 and 2018. The main effects of topsoil depth, crop
species and cropping year, and their interactions are all highly
significant (P < 0.001). Values with means ± standard
error (n=3). Within a growing season of each panel, values with a same
letter are not significantly different (P > 0.05).
Fig. 2. Effect of topsoil depth on root and shoot biomass of
maize at the jointing (V7) and milk (R3) stages, and of soybean at the
initial flowering (R1) and seed-filling (R6) stages in 2017. Values with
means ± standard error (n=3). Within a growth stage of each panel,
values with a same letter are not significantly different (P> 0.05).
Fig. 3. Effect of topsoil depth on N, P and K uptake in shoot
of maize at the jointing (V7) and milk (R3) stages, and of soybean at
the initial flowering (R1) and seed-filling (R6) stages in 2017. Values
with means ± standard error (n=3). Within a growth stage of each panel,
values with a same letter are not significantly different at (P> 0.05).
Fig. 4. Effect of topsoil depth on N, P and K uptake per unit
root length of maize at the jointing (V7) and milk (R3) stages, and of
soybean at the initial flowering (R1) and seed-filling (R6) stages in
2017. Values with means ± standard error (n=3). Within a growth stage of
each panel, values with a same letter are not significantly different at
(P > 0.05).
Fig. 5. Effect of topsoil depth on the concentrations of
available N, P and K in the rhizosphere soil of maize at the milk stage
(R3), and of soybean at the seed-filling stage (R6) in 2017. Values with
means ± standard error (n=3). Within each panel, values with a same
letter are not significantly different at P > 0.05
among treatments in two crops (2-way ANOVA).
Fig. 6. Effect of topsoil depth on enzyme activities in the
rhizosphere of maize at the milk stage (R3), and of soybean at the
seed-filling stage (R6) in 2017. Values with means ± standard error
(n=3). Within each panel, values with a same letter are not
significantly different at P > 0.05 among treatments
in two crops (2-way ANOVA).
Table 1. Significant level (P ) of main effects and
interactions of topsoil depth and crop species on grain yield (2016,
2017, 2018), growth parameters (2017), nutrient uptake (2017), and
concentrations of available nutrients (N, P and K) and activities of
enzymes in the rhizosphere soil (2017) of maize at the jointing (V7) and
milk (R3) stages, and of soybean at the initial flowering (R1) and
seed-filling (R6) stages.
Fig. S1. Effect of topsoil depth on N, P and K uptake in root
of maize at the jointing (V7) and milk (R3) stages, and of soybean at
the initial flowering (R1) and seed-filling (R6) stages in 2017. Values
with means ± standard error (n=3). Within a growth stage of each panel,
values with a same letter are not significantly different (P> 0.05).
Fig. S2. Effect of topsoil depth on total root length of maize
at the jointing (V7) and milk (R3) stages, and of soybean at the initial
flowering (R1) and seed-filling (R6) stages in the top 30 cm of soil
profile in 2017. Values with means ± standard error (n=3). Within a
growth stage of each panel, values with a same letter are not
significantly different (P > 0.05).
Table S1. The effect of topsoil depth on the concentrations of
N, P and K in root, stem and leaves of maize at the jointing (V7) and
milk (R3) stages, and of soybean at the initial flowering (R1) and
seed-filling (R6) stages in 2017. Values with means ± standard error
(n=3). Values with a same letter are not significantly different between
topsoil depths (P > 0.05).