Take a clear plastic or glass
jar, fill the jar a little more than
halfway with distilled water,
then pour in your sifted soil
sample. You will want to remove
the rocks first. Place and secure
the lid, then shake thoroughly.
When you set the jar down, time
for 20 seconds and mark a line
where the sediment has laid.
This will be sand level and the
larger sand particles will settle
within this amount of time. Then
at 1.5 minutes make another
mark as this will represent the
silt line. After 10 to 30 minutes
the sample should have cleared,
mark where the sediment is,
as this is the clay line. You will
not be able to visibly see the
lines demarking the various
soil particle separations as
in reality the size differences
are very gradual.
After measuring the height of
each line, you can then either
calculate the percentage of
each of these particles and find
that combination on the soil
pyramid chart, or scan the QR
code at the end of this article
and use the link there to access
the jar test calculator.
If your soil is loam or silt loam,
the amount of amendments
needed is not too great. Sandy
soil can be improved with water-
holding amendments, but high-
clay soil will only tend to remain
hard and poor-draining. It is
often best to grow veggies in a
raised bed with imported soil if
your native soil is more than 25
per cent clay. Tough soils either
do not drain adequately or they
drain too fast. Sometimes the
soil composition is fine, but the
chemical nature of the soil is
hostile to plants if the pH is
too high or too low.
Soil Drainage
Too Slow — Too Fast
A common issue faced when
growing in outdoor soil is
the drainage rate. Though
hydroponic solid grow media
systems drain rapidly, this
aspect is accounted for by the
particular system set-up. In
soil, when the percolation rate
is quicker than an inch per
minute, soil moisture is gone
long before the next irrigation.
This is a very tough growing
condition and, if not checked
before planting, will very likely
mean plant failure.
For sandy soil to hold moisture
it is necessary to amend the
planting hole by putting a
moisture-retaining product like
coir or peat moss under the plant
and mixing an amendment like
this with the soil that is placed
around the plant. With rapid
drainage, not only does moisture
leach away quickly, but so do
nutrients. Even when amending
with a moisture retention
product, it will be important to
use slow-release nutrients and
apply them more frequently. The
symptoms of malnutrition are
many and include yellowing
leaves, sparse foliage, and very
weak production of fruit.
A more common problem
growing in tough soil is when
there is high clay content and
its associated slow drainage
rate. When the percolation
rate is slower than an inch in
20 minutes, we encounter a
new set of problems. First,
drip irrigation with a timer
is common and this type
of soil will require a run or
application time sufficient to
penetrate at least 12 inches.
“Soil is comprised
of inorganic
particles and
categorized into
three different
sizes; clay,
silt, and sand.”
Maximum Yield
59