Agriculture Reference
In-Depth Information
A
B
9
400
8
300
7
pH
6
200
5
5
100
4
0
Initial
Final
Initial
Final
C
D
800
2
600
1.5
400
1
200
0.5
0
0
Initial
Final
Initial
Final
E
F
100
100
FA
HA
80
80
60
60
40
40
20
20
0
0
Initial
Final
Initial
Final
FIGURE 20.3
Changes in some properties of pig manure after 2 months of effective vermicomposting with
the earthworm
Eisenia andrei
: (A) effect of the vermicomposting process on pH; (B) carbon mineralization
during vermicomposting; (C) nitriÝcation during vermicomposting; (D) heavy metal availability (extractable
with ammonium bicarbonate diethylene triamine pentaacidic acid (AB-DTPA) after vermicomposting; (E)
humiÝcation during vermicomposting; (F) germination index of
Lepidium sativum
in vermicompost from pig
manure.
that earthworms (
E. andrei
in this case) provided conditions in the manure that favored nitriÝcation,
resulting in the rapid conversion of ammonium into nitrates. Similar results have been reported by
Hand et al. (1988), who found that
E. fetida
in cow slurry increased the nitrate concentration of
the substrate (Atiyeh et al. 2000a) (see
Chapter 18
, this volume).
V
ERMICOMPOSTING
AND
H
EAVY
M
ETAL
A
VAILABILITY
It is important to follow changes in the total and available contents of heavy metals in the organic
wastes during the vermicomposting process because they may cause problems in some animal
manures, sewage sludges, and industrial organic wastes. In our experiments, the total amounts of
heavy metals increased (by between 25 and 30%) as a consequence of the carbon losses by
mineralization during vermicomposting, and the amounts of bioavailable heavy metals tended to
