SOIL INGREDIENTS EXTRACTED BY THE ALMOND AS COMPARED WITH OTHER ORCHARD
TREES, AS SHOWN BY ANALYSIS OF 1000 LBS. EACH OF THE CROPS IN A FRESH
CONDITION
Phosphoric Total
Potash, Lime, Acid, Ash, Nitrogen,
Fruit lbs. lbs. lbs. lbs. lbs.
Almond (hulled) 5.49 1.72 4.33 15.00 16.40
Almond (not hulled) 9.95 1.04 2.04 17.29 17.01
Walnut (hulled) 1.50 1.81 2.78 7.50 10.20
Walnut (not hulled) 8.18 1.55 1.47 12.98 5.41
Chestnut (hulled) 3.72 .71 1.89 8.20 8.00
Chestnut (not hulled) 3.67 1.20 1.58 9.52 6.40
Prunes (green) 2.66 .13 .53 4.03 1.48
Apricots (green) 2.83 .18 .71 5.16 2.29
Olives 8.85 2.32 1.18 94.63* 5.85
* 80.7 pounds of which is silica.
_Humus._—A plentiful supply of humus in the soil is essential. It not
only improves the physical condition of the soil, but assists drainage,
moisture retention and in rendering the plant food available in
sufficient quantities for the use of the trees and for the maturing of
full crops of almonds. Many orchards have been very light producers year
after year because of a deficiency of humus in the soil.
_Drainage._—The almond root is very particular as to its air and moisture
requirements in the soil. It will not endure standing water in the soil
for any length of time, especially during the growing season. Exclusion
of air by excessive moisture is believed to be one of the most productive
causes of “sour-sap.” If allowed to continue for any length of time such
conditions will cause the death of many or even all the roots and with
them the top.
_Water Table._—A factor which is very commonly overlooked in connection
with the natural drainage of almond lands is the position of the water
table at different seasons of the year. Great care must be exercised in
choosing a location to be sure that the water table does not rise during
the summer. This is a very serious problem in many irrigated sections.
Where the water table during the winter months is less than 12 feet in
depth it is highly desirable to have as little fluctuation as possible.
Where fluctuations take place at a greater depth than 12 feet they are
not generally serious. The ideal condition is where the water table is
highest in the winter and quickly drops after the winter rains are over,
to a depth of from 10 to 12 or 15 feet, remaining at that point during
the remainder of the growing season.
The soil in addition to being well drained, must be sufficiently
retentive of moisture to supply the tree throughout a long, dry
growing-season. If the soil will not retain a sufficient amount of the
winter and spring rains, recourse must be had to irrigation to supply the
deficiency.
_Alkali._—Alkali lands are unsuited to almond culture and should be
carefully avoided.
In summarizing the soil requirements for almond culture, it may be
stated that the ideal almond soil is a medium loam, uniform in texture,
or nearly so, to a depth of at least twelve feet, well drained and
yet retentive of moisture for the use of the tree during the summer.
Fortunately some of the best almond soils are situated along stream banks
where the land is relatively high, and is, therefore, less subject to
frost. These streams flowing from the mountains and foothills have built
up their own beds by the detritus brought from the hills. The coarser
particles being deposited first and nearest the stream itself, make the
better drained soils, while the finer particles and the clays, deposited
further back from the bank and in the lower lands, form the heavier soils.
The various conditions mentioned above are what the tree should have for
best conditions of growth and production. Oftentimes these conditions
may be approached without the soil being as deep as ten or twelve feet.
Exceptions to this will be mentioned in discussing the various almond
districts of the state. It is essential to understand that trees,
while growing and bearing on shallow soils in some localities, do so
because of other exceptionally favorable conditions; either the soil is
exceptionally well drained and yet sufficiently retentive of moisture, or
the humus in the soil is plentiful and the roots are able to work into
the underlying partially decomposed rock for moisture and some plant
food. In such localities the trees bear comparatively well because of the
exceptional freedom from frost in the spring. Trees in these localities
are generally smaller than on the deeper, richer soils, and where other
conditions are equal, they bear crops in proportion to their size.