Tips for Amending Problem Soils

Rocky soils
often
lack
nutrients
that
plants
need,
and they’re not good at holding water. They’re also hard to dig or till. Removing the rocks will make
cultivating your garden easier and help
plant roots penetrate the soil.

Once
you’ve removed as many rocks as
possible,
use a shovel to break up
the
soil to a depth of about eight inches. Next,
work in three to five
inches of organic matter, such ascompost or well-rotted
manure.

If you have
more rocks than you can
remove, rake a layer of topsoil to your garden spot or
plant
your
flowers or vegetables
in raised beds
filled with good organic planting soil.

While you can see rocks in your soil, it’s not as easy to know if
it
contains clay.
Clay doesn’t let water
drain
readily,
so
pools of
standing
water
are often signs
of its presence.
When clay soil dries out, it may crack.

To test for
clay,
use a garden trowel to dig up a small
handful
of subsoil
(the layer of soil underneath the topsoil). Moisten
it with
some
water,
shape it into a ball
and
drop the ball onto the ground. If it stays in a clump
and doesn’t break apart, you have clay soil.
Repeat this test with samples from different places in your garden, since you may not have clay everywhere.

You can improve clay soil, but don’t work it when it’s wet, and avoid walking on it so it doesn’t become compacted. When it’s dry, add
three to four
inches of organic materials, such as compost, leaf mold
or
well-rotted manure
(not peat moss),
and work them into the soil
about
six
inches deep.
Mulch the soil with
bark, wood chips
or
some other type of mulch that decomposes slowly. Over time, the sun and rain break down the mulch, which will also improve your soil.

Growing a cover crop from seed
can also help. Try clover, winter rye or legumes to build up healthy soil.
Sow the crop in
the
fall, after your garden is finished. It
will
also help control erosion and keep weed seeds from
sprouting. Cover
crops can be turned under
to add more organic matter
to
the soil
when
you
plant again in spring.

Heavy foot traffic can compact soil; so can driving over it. Once soil is compacted, water can’t easily penetrate. An aerator can help break up the soil if it isn’t severely compacted, so you can work in two or three inches of compost. Add pavers or stepping stones to help avoid further compacting the soil.

Sandy soils aren’t good at holding
water
or nutrients, but they’re
easy to
identify.
Sand
feels
gritty and
won’t form a ball in your hand.

Fortunately,
sandy soil is
easy to dig, so work in
two or three inches of
peat moss or perlite to help it retain water.
To
add
nutrients, work in compost, leaf mold, well-rotted manure or other organic matter.
When you fertilize, choose a slow-release product. Liquid fertilizers
can
move
through sandy soil too fast to benefit plants.

Plants can fail to thrive or die in soils with too much salt content. Saline soil can be present in arid regions, in areas with shallow water tables, near oceans or where minerals have weathered and broken down. Road salts can also accumulate in soil.

Improving saline soil is a challenge, so ask your County Extension Service agent for advice if this is a problem in your garden. Extension agents can also help you find salt-tolerant plants and suggest
organic materials, if any, that may help improve your soil.

Soil pH refers to the acidity or alkalinity of soil. It’s measured from zero to 14.
Acidic soils have a pH below 7.0,
while
alkaline soils measure over 7.0.
Seven is neutral.

Soil pH is important because it affects the ability of plants to use nutrients.
Most plants
will do fine
when the soil pH is between 6.0 (slightly acidic)
to 7.5 (slightly alkaline).
However, some plants, such as blueberries and azaleas, need acidic soil, and some trees, shrubs and perennials do better in alkaline soil.

A pH meter or test kit
lets you measure
your soil’s
acidity
or
alkalinity so you can amend it, if indicated. It’s a good idea to take soil samples from various places in your garden and combine the measurements to get your average soil pH.
Follow instructions in the soil test kit you purchased or you can use a soil test kit from your local County Extension agent.

If your soil is acidic,
use
ground
limestone
to
raise
the
pH.
If possible, apply it two or three months before planting, so it has time to work. Wood ashes from untreated wood will also raise pH. Spread them over the soil in the winter and work them in the next spring.

If
your soil is alkaline, aluminum sulfate
or sulfur will
lower its pH.
Aluminum sulfate changes the pH right away. Sulfur works more slowly.
Changing the soil’s pH usually requires several treatments, so retest until you reach the pH you need. Also, retest when you plant a new garden.

Again, it's recommended that you amend your soil on a regular, consistent basis with organic matter. Amend your pH as the soil pH testing indicates.

Vegetable gardens benefit from a top dressing of organic compost in spring and/or fall or in mid-season. Simply pull away any
mulch and spread
two to three inches of compost
or well-rotted manure over the soil.
Then replace the mulch. You
don’t need to work the compost into the
soil;
it
will break down naturally and
release
nutrients.
As a bonus, top dressing can help discourage weeds from growing and help the soil retain moisture.