Site Selection and Soil Preparation - Understanding Vineyard Soils - page 46

Table 2.2 Soil Profile Properties Relevant to Site Selection for Vineyards

Key soil property Relevance of this property Method of measurement

Soil depth—whole
profile or depth
to a compacted
(impeding) layer

Affects rooting depth and the
possibility of waterlogging; may
indicate a need for deep ripping

In centimeters; a compacted
layer resists insertion
of a penetrometer (see
“Consistence”)

Color Orange to brick-red colors (resulting

from ferric oxides) indicate good
drainage; dark colors indicate
organic matter; “mottling” indicates
periodic waterlogging (see box 1.3,
chapter 1)

By eye (important to specify
whether soil is wet or
dry); describe mottles and
background soil color
separately

pH Affects the availability of several

nutrients; pH <4 and >9 inhibit
root growth

Universal indicator in the field
(accurate to ±0.5 pH units) or
a pH meter in the laboratory

Texture, stones,
and gravel

Influence a soil's water-holding
capacity, drainage, structure, and
ease of cultivation

Field texturing (table 2.1) or
particle-size analysis in the
laboratory; proportions of
gravel (2-20 mm) and stones
(20-60 mm) estimated by eye

Structure,
including
sodicity and
cracking

Influences soil stability when wet,
hard-setting when dry; also
determines aeration, drainage,
and ease of root penetration;
montmorillonite (cracking) clays
swell when wet and shrink when
dry

From a spade sample, assess the
degree of aggregation as well
as aggregate sizes and shapes;
note frequency and width
of cracks; check stability of
small aggregates placed in
distilled water or rainwater
(see figure 4.5, chapter 4)

Consistence Describes the strength and bulk

coherence of a soil, which influence
drainage, root penetration, and ease
of cultivation

Test ease of crushing dry
20-30-mm aggregates
between finger and thumb or
underfoot—“loose,” if very
easy, to “rigid” if very hard;
measure bulk soil strength
with a penetrometer (see
“Measuring Soil Strength in
the Vineyard,” chapter 4)

Presenceof
limestone or
chalk (CaCO 3 )
and its hardness

Indicates neutral to alkaline pH;
usually associated with good
structure but can restrict rooting if
very hard

Drops of dilute hydrochloric
acid cause fragments to fizz
from CO 2 release; if rock,
note whether fractured or not

Rippable rock
or impeding
subsoil layer

Influences rooting depth and soil
drainability; if fractured probably
can be ripped

Assess hardness with a
geological hammer; estimate
the extent of fracturing