Environmental Engineering Reference
In-Depth Information
No fertiliser
application
Time of fertiliser
application
Scarification
& seeding
SUMMER
SUMMER
AUTUMN
WINTER
AUTUMN
&
SUMMER
AUTUMN
AUTUMN SUMMER
30
25
20
15
10
5
0
LSD***
CONTROL
I
TD
I
TD
TD
TD
NATURAL
FOREST
Fertiliser placement
0
10 20
0
1
20
0
10 20 0
10 20
0
10
20 0
10 20 0
10 20
0 10 20
0-
5-
10-
20-
Colwell extractable soil P (mg L
-1
)
Time of fertiliser
application
Scarification
& seeding
No fertiliser
application
WINTER
AUTUMN SUMMER
SUMMER
SUMMER
AUTUMN
AUTUMN
AUTUMN
&
SUMMER
30
25
20
15
10
5
0
LSD***
TD
TD
TD
TD
I
I
NATURAL
FOREST
CONTROL
Fertiliser placement
0 0
01020
0 10 20
10 20
10 20
0 10 20
0 10 20
0 10 20
0-
5-
10-
20-
Colwell extractable soil P (mg L
-1
)
Figure 15.11.
Collwell extractable soil phosphate comparisons between fertiliser
placement (incorporated (I) and top-dressed (TD)) and timing in furrows
j
and ridges
□
(formed following deep ripping) (***P
<
0.01) (after George et al.
2006
).
aspects of biological fertility return quite nicely to the levels found in pre-mining
systems; for example, enzymes important in nitrogen cycling such as chitinase
(1,4-beta-poly-N-acetylglucosaminidase EC 3.2.1.14) can be found to match the
range innatural forests verywell (
Fig. 15.12
) (Spain et al.
2006
). Other aspects of soil
biology, however, seem to fall short of natural systems, even after a quarter of a
century of forest regrowth.
