MISCELLANEOUS WHYS … BY GLADYS JEURINK
Every so often
someone who may not agree with me asks a question. One of these is why I
don’t recommend aluminum sulfate to acidify my soil and lower the pH.
I lower the pH of my soil as I have a number of plants that do not do
well in our alkaline soil. Included are azalea, rhododendron, holly, and
blueberries. Many years ago, in my first agronomy class, we were told
that too much aluminum would tie up the phosphorus, making it impossible
for the plants to get any. Phosphorus is one of the three major
components you will see listed on any bag of fertilizer. The first
number is for nitrogen (N), the second number is phosphorus (P), and the
third number is potash or potassium (K).
The first sign
of a phosphorus deficiency is a reddish, purple discoloration of the
leaves of a plant. Phosphorus
is essential in a number of plant functions such as flowering and
fruiting, and seed production, resistance to disease and root
development. The starter fertilizers that you see every spring planting
time are high in phosphorus as well as the ones who promise to make your
plants bloom. So you can see it would be easy to overdose with aluminum,
and it is rather expensive compared to granular or powdered sulfur.
question that is often asked is about Epsom salts and why or where it
should be used. The book “Clematis Care Manual” by Mary Toomey, says
that magnesium deficiency causes clematis leaves to turn yellow between
the veins. Also it causes leaves to drop. She recommends the use of
Epsom salts at the rate of 1 oz per 10 square feet of soil. It should be
scratched into the soil during autumn. In the American Rose, Belindy
recommends one tablespoon of Magnesium sulfate (Epsom salts) around each
rose bush once a month during summer and a handful early in the spring,
sprinkled dry and then raked and watered in to promote new canes and
handsome leaves. You can buy it in a drug store or in 50 pound bags at a
farm supply store. Many
tomato growers treat their plants in this same way. George mentioned
magnesium in one of his earlier articles.
fertilizers are also called micro-nutrients. I am asked, “What are
they and what do they do?” In general if you are making and using
compost you already have them as what comes from a plant feeds another
one. The definition is
“those chemicals used in very small quantities by plants but essential
for their well being”.
Elizabeth Still in “Secrets to Great Soil”, micronutrients
deficiencies occur only in very acid or very alkaline soils or
intensively gardened ones using only “synthetic” fertilizers without
compost or other organic material.
Among these micronutrients are boron, copper, manganese,
molybdenum, and zinc. It is better to check before you add any of these
as plants use very little and an overdose can be very toxic. She also
recommends adding them to the compost pile rather than a direct use.
Sometimes if you read the “doom and gloom” magazines there
are statistics about how little nutrients we are getting in our food as
the soil has been “used up” with the plants unable to pick up these
things because they aren’t there. My favorite plant food for many
years was wood chips used for horse bedding and then shoveled outside in
huge mountains to sit in the sun and rain where it partially composted.
Dug in every fall it supplied all the nutrients I needed as well as
constructing spaces for air and water.
The fall application gave it time to break down partially thus
releasing the nutrients.
questions asked is “How often and how deep should I till?” I can no
longer till as my plants are too close together with no free space,
unless something terrible happens that really disturbs the garden. One
agronomy professor I had hated rototillers as they:
Changed the soil from good structure to dust that would blow
Brought up all the buried weed seeds to the surface where they
My compost, which
never gets really finished, is on top of the soil for earthworms to eat
and take down to the roots. As it goes through their digestive system it
becomes “castings” which you can buy to add to your soil.
Have you looked into the new “No Till” concept that farmers
are using and how it works? It keeps soil from erosion during winter and
fall rains, as the roots decay they leave passage ways for water and
fertilizer to run down.
question I was asked is “Have you ever dug in your garden and met
hardpan”? “Hardpan” is a hard layer of soil that does not let
water, roots, or anything else get any deeper. You can make
“hardpan” in your own garden by digging or tilling to the same depth
every time or by walking or using equipment on wet clay soils. This is
especially a problem with tillers when you continually till at the same
depth. Those tines pound the ground at the same depth year after year
and create hardpan.
When my husband
and I tried to plant trees in the parkway, they didn’t do well and by
digging I discovered hardpan just below the root ball. As a result, the
root ball space was holding water, so of course they were drowning.
We went on either side of their root ball and dug holes down
until we reached a looser layer of soil and then filled the holes with
rock and gravel to produce drains for each tree.
During construction that area was used for parking and was
heavily traveled by equipment thus making a different species of cement
and a layer of hardpan. Now, because of our double digging and the
addition of compost, that area is some of my best soil.
I can actually plant with a spoon. The bad part is that it erodes
easily and I can’t use that soil to plant water lilies as the soil
would float away when the container is placed into the pond. You can
help your garden soil by double digging, adding lots of organic matter
such as compost, and not walking on the soil when it is wet. Plants will
grow much better if the soil is not just the hard clay. The ideal is
about 30% compost to 70% soil.
2006 NEIGHBORHOOD GARDEN FOR
OCTOBER 7, 2006