Agriculture Reference
In-Depth Information
Relatively warm
air over water
rises at night
Cool air over the
land “drains” down
slope
Figure 8.4
A convection cell on a clear night for a vineyard near a large river (redrawn from
Gladstones 1992).
to the moderating effect of these convection cells, vineyards near water bodies do
not suffer the extremes of temperature, either diurnal or seasonal, that occur in
continental climates (section 3.5.3).
Vineyard Establishment
8.4
8.4.1
Soil Preparation
Soil preparation starts in summer. If the land has been cleared of trees or old vines,
all residues must be removed or burnt. The soil should be plowed (usually with
a chisel plow) to bring up old roots.
Deep ripping
may be necessary to break up
a restrictive layer at depth (an old plow pan, an iron pan, or a concretionary
layer; see section 3.2.4). In old vineyard soils, the compaction from traffic in the
inter-rows can be serious, especially in sandy soils, but this can be alleviated by
ripping. Many duplex soils in Australia have a compacted A2 horizon, which can
be improved by mixing with the better structured A1 horizon (Myburgh et al.
1998). On the other hand, vineyards established on calcareous soils in Hérault,
France, which have been mixed by deep moldboard plowing, have suffered root
growth problems (see fig. 7.12). These soils also have been overcultivated with ro-
tary hoes.
8.4.1.1
Deep Ripping
To shatter the restrictive layer, deep ripping is best done during late summer and
autumn, ideally when the subsoil is slightly drier than the lower plastic limit, so
the bulk soil will not smear as the ripper blade passes through, but rather will
shatter. In some cases it may be necessary to sow a winter cereal, to be harvested
the following summer, to dry the soil profile sufficiently before deep ripping. The
methods and conditions for successful deep ripping are described in box 8.4.
After deep ripping, the land is leveled and prepared for planting. Fumigating
for nematodes is most effective when the soil is dry (to maximize the air-filled
