Preparing or Upgrading Your Orchard Site - Growing Organic Orchard Fruits - page 117

Limestone. It is quite easy to raise pH on acidic soils by using limestone (cal-
cium carbonate). If your soil test shows both low pH and low magnesium,
apply dolomitic limestone (also known as dolomite), which is primarily
calcium-magnesium carbonate. Do not use dolomitic liming products if your
soil calcium is low (see table 4.6 ➔ ) unless soil tests show soil magnesium
concentrations are also low. This is particularly important for apples. Mag-
nesium can interfere with the uptake and utilization of calcium in fruit trees,
increasing problems with bitter pit disorder in stored apples.
Wood ashes. Strongly alkaline, wood ashes can be used to raise soil pH
while also supplying some nutrients, as shown in table 8.4 ➔ . They are al-
lowed in organic production, although they can be problematic. Use only
ashes from untreated and unpainted wood. Ashes created from treated
woods, colored paper, plastic, and other materials are prohibited under or-
ganic certification guidelines. Never use coal ash. Apply ashes sparingly be-
cause excessive amounts can cause pH and nutrient imbalances. Wood ash
is highly alkaline and reacts very quickly in the soil to raise the soil pH.
Unfortunately, the liming equivalent of wood ashes varies greatly de-
pending on the source and handling of the ashes. In general, wood ashes
have a calcium carbonate equivalent (CCE) of 25 to 60 percent of calcium
carbonate, and you need to add two to four times as much wood ash as lime-
stone, by weight, to create the same change in soil pH.
Do not apply wood ashes to soils that are already at or above the desired
pH, and do not add more than 20 pounds per 1,000 square feet per year. At
this rate, you would be adding the equivalent of about 220 to 520 pounds of
100 percent calcium carbonate per acre per year.
Sugar beet lime. Also called spent lime, sugar beet lime can be used for rais-
ing the soil pH in some organic orchards (check with your certifying agency).
This material is a by-product of sugar beet processing in which a suspension
of finely ground calcium hydroxide (slaked lime or hydrated lime) is mixed
with carbon dioxide and the sugar extracted from sugar beets. The lime does
not come from the sugar beets themselves or any other plant material.