bone meal basics
Certain regions in the United States
are more prone to calcium deficiency
than others. In the Northwestern
and Eastern states, calcium is readily
leeched out of the soils from rainfall
and irrigation. The precipitation
soaks into the ground and pushes
the calcium from the upper layers of
the topsoil downward. Other regions
with large compliments of limestone,
gypsum or apatite are usually high in
calcium. Coastal states with coral or
marine shells in the soil tend to be
rich in calcium as well, particularly
calcium carbonate.
Other organic and natural sources
of calcium include eggshells, gypsum
and lime, although lime should not
be used on soils that have a pH higher
than 7. Adding too much calcium to
your soil can raise pH levels, making
soil more alkaline. Many food crops
can be harmed by additives that raise
the pH too high. If you need to add
calcium and also raise the pH, limestone should be considered instead
of bone meal. If you need to add
calcium, do not need the phosphorus
boost of the bone meal, and do not
wish to raise your soil pH, gypsum
(calcium sulfate) should be used.
Precautions
As useful as bone meal is, it may not
be a panacea for phosphorus-starved
soils or plants. Recent research from
Colorado State University suggests
phosphorus from bone meal is only
available to plants in soils that have
a pH below 7. For alkaline soils,
research shows it is best to use composted or vermi-composted manure
as a source of phosphorus. Soils with
64
Maximum Yield USA | April 2015
“When applied as a top-dressing, bone
meal can attract dogs, raccoons, coyotes and
other carnivorous and omnivorous animals.”
a pH level of 7.5 and above often have
high calcium concentrations that tie
up phosphorus as calcium-phosphate.
Calcium phosphate is an insoluble
compound not available to plants.
Over-application of bone meal can
have negative effects on plants and the
surrounding environment. Most soils
contain some quantity of natural phosphorus, except for soils that have been
farmed for several successive years.
Too much phosphorus will continue
to promote root growth, but in excess,
it interferes with the roots’ relationships with mycorrhizal fungi. Without
the mycorrhizal fungi, the roots have
a more difficult time developing and
using the nutrients that surround it.
Phosphorus runoff, though much
more prevalent with synthetically
produced phosphorus than the form
found in bone meal, can hasten the
eutrophication of nearby waterways.
Eutrophication is the emergence of
undesirable algae and underwater
weeds that grow as the result of the
increased nutrient supply. As the
biota die and decompose, bacteria consume dissolved oxygen,
resulting in oxygen shortages
in the water bodies. It is
important both economically
and environmentally to apply
only the amount of phosphorus required for your
specific crop or soil.
When applied as a
top-dressing, bone
meal can attract dogs,
raccoons, coyotes and
other carnivorous
and omnivorous
animals. It should
be well incorporated into the soil
by tilling, raking
or spading, and
then watered in
to leave as little
on the surface
as possible to
avoid damage
to your garden
by scavenging animals.