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 If
there is one thing that is the secret to good
gardening, it is soil. Soil is more important than
what varieties of plants you choose to grow, more
important than planting and propagation techniques,
and more important than weed control or
cultivation. A big mistake beginning gardeners
often make is to spend their budget of money, time,
and energy on plants, with only brief or
perfunctory attention to the soil.
Here in
northern New Mexico, March and April is the time
for working the soil in preparation for planting in
May and June. It's important to give soil
preparation a lot of your attention now, and not to
rush or cut corners. You'll be thankful for your
efforts this summer.
I always
remember something I read when I first began
organic gardening, decades ago: Feed the
soil, not the plants. Synthetic chemical
fertilizers can give plants a quick shot of energy,
but they harm the soil over the long term, leading
to a cycle of ever-escalating chemical use.
Creating healthy soil takes more time and attention
from the gardener, but it is healthier for the
plants we grow, for the environment, and for our
spiritual well being.
So how does
one feed the soil? There are two things to think
about: nutrients and structure.
Nutrients
are the elements that plants draw from the soil
through their roots and use to grow. The three most
important are nitrogen, phosphorus, and potassium.
Of these, potassium is rarely a concern in New
Mexico (or most of the western US). Arid soils are
often lacking in nitrogen, and phosphorus can be in
short supply as well. Synthetic chemical
fertilizers put these elements into the water
almost instantly, which is why they can produce a
sudden change in the plants (and why they can also
harm the plants if too much is used). After the
initial jolt, they drain away with the water and
are gone. Organic gardeners use compost or natural
minerals to provide the nutrients plants need.
These release their nutrients very gradually, over
time, so that there is always some available to the
plants whenever they need it.
The
structure of the soil is at least as important as
the nutrients it contains. Most plant roots require
a soil that is strong enough to anchor them, and
that holds both water and air. Sandy soils are made
of relatively large grains that are very bad at
holding water. (The water easily flows down between
the sand grains, so the sand is soon dry again.)
Clay soils are made of such tiny particles that
they pack together with almost no air space between
them. These soils hold onto water well, but without
air the plant roots cannot breathe and may
literally rot in the soggy clay. Wonderfully, the
cure for both types of soil is the same: organic
matter!
Organic
matter (peat moss or compost from plant matter or
animal manure) is fibrous and light, improving
sandy soils by providing lots of surfaces for water
to cling to, and improving clay soils by breaking
up the dense clay and creating numerous tiny air
pockets.
If you do
nothing else when making a new garden, do this:
cover the ground with a thick layer of peat moss or
compost and mix it in to the top foot or so of the
soil. And I do mean a thick layer: at least 2
inches, and preferably more like 4. This is
guaranteed to improve the texture of the soil, and
will provide some nutrients as well. It's an
investment in the future health of the soil, too.
It doesn't disappear in a few weeks like synthetic
fertilizer. The benefits will last for years. Soils
rich in organic matter also attract and delight
earthworms, who work tirelessly aerating and
conditioning the soil, even when you're not
around!
If you want
to provide a little more nutrients to the soil than
peat moss or ordinary compost does, there are
organic products you can apply for that purpose.
Bone meal and blood meal are often used by organic
gardeners, but we chose not to use these in our
garden, because they come from the killing of
animals. We used rock phosphate to provide
phosphorus, and cottonseed meal for nitrogen. These
are both very rich in their respective nutrients,
so not a lot is needed - just a good dusting on top
of the soil before digging in does the
job.
Digging all
this stuff into your soil also provides a good
opportunity to remove rocks, break up clumps, hunt
for 20-year-old bottlecaps, and generally transform
a plot of earth into a garden. I also install a
watering system at this time. I buy long soaker
hoses (they are made from recycled tires), and bury
them a couple inches below the surface, snaking
through the garden. Whenever the garden needs
water, I send a very slow flow through the soaker
hose, which delivers water to the plant roots
gradually over a period of many hours. The concept
is similar to drip irrigation, but there is much
less to fuss with, and the hoses are actually down
under the soil surface, so there is virtually no
loss of water to evaporation, and no unsightly
irrigation mechanics above ground.
Once a
garden has been started in this way, with lots of
organic matter mixed in, it is easy to maintain its
health from year to year. A backyard compost bin
provides fresh organic matter when new plants are
added in subsequent years, and the earthworms do
their part too. Some people are very intense about
composting, buying special equipment and making
sure they have just the right mix of different
kinds of material in their compost at any given
moment. I'm more laid back. I'm in no great rush to
produce compost as quickly and efficiently as
possible. Last year's pile is usually ready to use
after it's been through a winter and a spring thaw
. . . just like last year's leaves go back to the
soil in nature.
Once soil is
healthy, it takes care of itself. Earthworms are
just one particularly visible member of the
community of animals, plants, and microorganism
that live and grow in a healthy soil. They all
contribute to keeping the soil rich and
vital.
Many of our
soils have been damaged by overgrazing, industrial
agriculture, or years of indifferent treatment by
homeowners. Planting a garden the right way, by
first restoring the soil, makes a lasting
contribution to the ecological health of the place
where we live.
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