Fig. 1
- Schematic representation of the role of the decision process in the management of the
agronomic system
Fig. 2
- Typical possible patterns of yield variation in the long term (order of decades) alter a change
in crop-ping system. The dashed line indicate potential reversibility
34
Fig. 3
- Change in porosity in two maize fields along the season. The arrow indicate first ploughing:
in winter the soil froze [Unpublished data by Cavazza et al.]
Fig. 4
- Interaction of depth of ploughing in two subsequent years on the soil bulk density (
a
) at
different sampling depth. After 8 years the effect of previous-year tillage is evident and varies at
different sampling depth [42]
35
Fig. 5
- Effect of tillage at different constant depths during 13 years on the mean diameter of small
pores (
< l
m). The 10 cm tillage was roto-tilIed the other two case were ploughed
[Unpublished data by Patruno et al.]
Fig. 6
- Effect of tillage at different constant depths during 7 years on soil structure stability to water
(wet sieving after Hénin pretreatment on crumbs 0.2 to 1 mm
d
). [Unpublished data by Cavazza et
al.] Dashed line = at a depth 0-10 cm. Dashed and dotline: at 30-40 cm
36
Fig. 7
- Seasonal variation of soil structure stability to water (wet sieving after alcohol pretreatment;
crumbs 3-5 mm
d
). as affected by tillage tools and sampling depth. The numbers refer to the
order of sampling time in the 4-year observation period: n. 4. 5. 8 refers to soil after
ploughing while the other were chiseled. C =conventional tillage: M = minimum tillage;
t = top soil (0-5 cm): d =deep sampling (15-20 cm) [43]
Fig. 8
- Decline of saturated hydraulic conductivity (K
s
) in time under the action of sprinkling water
on the top of sieved samples to simulate soil crusting. (a) No-tilled soil (under permanent
grass cover since 6 years); (b) green manured with weeds each year: (c) roto-tilled each year.
The K
s
for no-tilled soil is about twice as that for the tilled soil [Unpublished data by Cavazza
et al.]
37
Fig. 9
- Variation of soil bulk density ascribed to frost action, as function of the tillage depth to the
previous crop (the 10 cm tillage was obtained by roto-tilling; the other by ploughing). This
effect was evident in plots later rote-tilled at 10 cm for wheat [42]
Fig. 10
- Variation of the soil moisture retention relationship at different sampling depths, as
function of tillage depth kept constant for 8 years. The 10-cm tillage was obtained by roto-
tilling, the other depths by ploughing [44]
38
Fig. 11
- Inverse variation of bulk density and saturated hydraulic conductivity at different soil depth
as function of different tillage depth in plots prepared for a row crop (roto-tilled at 10 cm or
ploughed deeper). Thick line = in tilled soil horizon; thin line = under the tilled horizon;
long term trial at the 13
th
year [Unpublished results; Cavazza et al.]
Fig. 12
- Cone penetrometer Index (C.I.) as function of soil moisture (% dry basis) and sand
(2-0.02 mm) content [27]
39
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