3.1.3 Carbon storage in soil
Bulk density of soil from the control was significantly higher than that
from any of the treatments at all depths up to 80 cm (Fig. 5) (SNK post
hoc tests, P>0.05, MS=0.255, F=15.488, df = 3), beyond
which the difference ceased to be significant, although the bulk density
increased with depth.
Concentrations of SOC decreased with depth (Fig. 6) and differed
significantly between the control and any of the three treatments at all
depths (other than 90–100 cm) (SNK post hoc tests, p>0.05,
MS=0.775, F=14.794, df=3). The values also differed significantly
between the treatments at some depths.
The contents of stored C (as calculated from the soil bulk density and
the concentration of C) at each depth are presented in Table 4. Although
bulk density was the highest in the control, it had significantly lower
stored C than that in any of the other treatments at all depths (SNK
post hoc tests, p>0.05, MS=201.857, F=12.969, df = 3). The
treatments differed significantly among themselves at all depths (SNK
post hoc tests: p>0.05, MS = 10.301, F = 0.509, df = 2).
The contents of stored C decreased with depth, with the highest values
in the 10–20 cm layer. The highest value was recorded in FG (18.82
t/ha, followed, in that order, by MG (14.91t/ha), UG (12.36 t/ha), and
CK (5.93 t/ha). The lowest values were recorded in the lowest or the
deepest layer (90–100 cm); at that depth, the rank order was somewhat
different: the maximum value was in MG (3.18 t/ha), followed, in that
order, by CK (1.64 t/ha), UG (1.45 t/ha), and FG (0.98 t/ha).