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).