Agriculture Reference
In-Depth Information
Box 2.6 Methods of Deep Ripping
To achieve shattering of a restricting layer or a dense subsoil, deep ripping is best
done in late summer to autumn. Ideally the soil water deficit (see “How a Soil
Water Deficit Develops,” chapter 4) should be about 50 mm in a sand or 100 mm
in a clay—this corresponds to a friable soil consistence when the soil aggregates
will crumble under light to moderate pressure (see “Soil Strength,” chapter 4).
The rationale for this condition is that the soil should not smear but shatter as
the ripper blade passes through. In some cases it may be necessary to sow a winter
cereal, to be harvested in the summer, to dry the soil profile before deep ripping.
Rip to a 1-m depth if possible. Achieving this depth requires a 1.5 m-shank and
a D8 or similar tractor. The subsoiler blade and its angle of strike are chosen
according to the problem to be alleviated, as shown in table B2.6.1. If the soil is
ripped at the correct water content (a friable consistence) at a 2-m spacing (with
wings attached), the fissures created by the blade should intersect at the soil surface.
This is important for good drainage.
Table B2.6.1
Recommendations for Ripping Subsoils
Soil problem
Blade type
Rake angle
a
Hard rock
Do not rip
Weathered rock
Rip with a wingless blade
Cemented layer in profile
Rip with a wingless blade
Clay subsoil
Rip with a winged blade
20 degrees from horizontal
Compacted sands
Rip with a 90-degree point
a
The angle of the blade is critical for proper lift and shattering of the soil, with minimal lateral
compaction.
Adapted from Cass et al. (1998).
such as contour banks or terraces are required to break up long slopes and divert
runoff water laterally, preferably to a grassed waterway at the edge of the block.
Old, established vineyards in Europe, such as the Hill of Hermitage in the
Rhone Valley, France, have broad terraces on which vines are planted in rows
up and down the slope (figure 2.14). In newer vineyards, the terraces are much
narrower so that vine rows must follow the line of the terrace across the slope,
as seen in the Friuli region of northern Italy (figure 2.15). Usually two or three
rows of vines are planted on each terrace, to make mechanical operations in the
vineyard easier. Although many older vineyards in the Mosel and Rhine Valleys
of Germany have been planted on very steep slopes, planting on slopes greater
than 15% is not generally recommended, except in the Vaud and Valais regions
