Organic matter in paddy soils from LVB
ranged from 1.8 to 12.4% (Table 2). The
differences in organic matter content between
the four sites (Figure 2a) were significant (p
= 0.026, KW = 9.227), soils from Magu
had the highest contents of organic matter.
Higher copper concentration in the soil was
also observed in samples from Magu (Fig.
2a), although the difference in Cu content of
the soils from the four sites was not
statistically significant (p > 0.05).
Cadmium concentration was generally low
in the soil samples (Fig. 2b) with no
significant difference among sites (p >
0.05). The concentration of Pb in the soil
ranged from 8.0 to 28.5 !g g-1, (the mean
was 18.9±7.4 !g g-1 ). Likewise, there was
no significant difference in Pb concentration
in the soil between the sites (p> 0.05). The
concentration of Cr in soil samples ranged
from 11.4 to 39.4 !g g-1 where Mwanza
City recorded the highest concentration of
all the sampling sites. It was however
observed that there was no significant
difference in Cr concentration in the soils of
the four sites (p>0.05). Zinc concentration
was higher in some samples from Magu and
Mwanza city than the average of 59.8 !g g-1
(Table 2), with significant difference (p =
0.031; KW = 8.894) among sites (Fig. 2c).
Dunn’s multiple comparison test showed a
significant difference (p < 0.05) in Zn
concentration between soils of Geita and
Magu as well as between soils of Bunda and
Magu. Total Hg content was highest (69.3
ng/g) in soil samples from Nungwe area
(Table 2), however, the THg concentration
was not significantly different (p>0.05)
among the four sampling sites (Fig. 2d).