Agriculture Reference
In-Depth Information
supply needed magnesium with calcium. It is used at the same
rate as regular lime, takes as long to act, and lasts as long.
Wood ashes are a long-neglected soil amendment for pH
correction. They contain a wide array of macro-nutrients such
as potassium and calcium; but also contain elements such as
iron, boron and copper. They act more quickly in correcting
soil pH, but do not last as long. Wood ashes are applied at
twice the rate of lime for an equal pH correction; but should
not be applied at a rate exceeding five pounds per 100 square
feet. So, in effect, wood ashes are always used in conjunction
with lime, rather than on their own.
The pH scale is a logarithmic value, similar to a decibel. As
such, the amount of lime needed to raise the pH from 4 to 5 is
greater than the amount of lime needed to raise the pH from 5
to 6. Furthermore, the effectiveness of lime is strongly
influenced by the type of soil. So the following table reflects
both of these factors. The numbers represent pounds of
powdered limestone per 100 square feet. For wood ashes,
double that number, but never exceed five pounds per 100
square feet in a given year. Wood ashes can seldom be used
exclusively as a pH modifier. Rather, they are best used when
mixed with lime. For example, if the table says I need 5.5 lbs
of lime, I can use 5 lbs of wood ashes in place of 2.5 lbs of
lime, plus 3 lbs of lime.
One further note about lime. A lot of sources say you
shouldn't apply fertilizer at the same time as lime because the
lime will react with the fertilizer and neutralize it. To some
extent, this is true. However, lime stays active in the soil for
as long as seven years, so the fertilizer will be affected
anyway. As long as both are thoroughly incorporated into the
