Download Building Healthy Soil to Grow Healthy Plants

OC0407
Michigan State University Extension-Oakland County
Building Healthy Soil
to Grow Healthy
Plants
What is Soil?
Soil is an intricate mixture of fine rock
particles, organic matter, water, and air.
Soils vary in texture – that is, the relative
proportions of sand, silt and clay. Soil
structure (the arrangement of soil particles
in the soil) also varies.
It is difficult to permanently change
soil texture. However, soil structure can be
substantially improved by adding compost or
other organic matter to the soil every year.
Soil structure is important because it
determines how effectively air and water
move into and through the ground.
Healthy soil also has a balance of
minerals, air, water and organic matter
which creates a comfortable environment for
deep, healthy root growth. Healthy soil has
many living things within it, including plant
roots, insects, and microorganisms such as
bacteria and fungi which cannot be seen
clearly without the use of a microscope.
Renew Your Soil with Organic Matter
Organic matter is the
remains, residue, or waste
products from any onceliving plants, animals, and
soil organisms. The addition
of organic matter improves
the soils’s structure and its
biological
activity.
The
organic matter helps to
hold moisture, gradually
releases nutrients to the soil system, and
supports
the
bacteria
and
other
microorganisms that support the life of the
soil. An easy-to-dig fertile soil is rich with
organic matter.
Organic
matter
continues
to
decompose after it is incorporated into the
soil. Nutrients from organic matter are taken
up by plant roots (like vitamins) to support
plant growth. As organic matter content of
soil drops, so does a garden’s fertility,
productivity, and beauty. Organic matter
should be replenished and renewed on a
regular basis.
How to Add Organic Matter to the
Soil
Natural mulches in garden beds
Top dress your soil with a 2” – 4” layer
of mulch on an annual basis. Mulches such
as shredded leaves, pine needles, grass
clippings, finely shredded bark, and cocoa
bean hulls – when in direct contact with the
soil – will slowly break down into compost or
humus – and then into raw materials which
can be used by plants. Earthworms, bacteria
and fungi in the soil do the decomposition
work, gradually working the organic matter
into the soil.
Soil renovations:
To undertake a complete garden
overhaul in the early spring or fall, remove
plants and bulbs and set them aside iin the
shade with soil around the roots. Weed the
bed well and mix a 4” layer of compost or
peat into the soil. Water the bed, let the
compost and soil settle, and then replant.
To undertake a partial renovation, dig
up soil around plants and mix in compost or
peat. A mix of 50% compost and 50% soil is
excellent.
Gradual soil replenishment
Every time you remove plants or
divide perennials take an extra moment and
replenish the soil by adding some compost.
Top soil does not have a high quantity of
organic matter. In contrast, compost will
often be 30% or more organic matter in
content.
Cover crops and “green manures”
In a vegetable garden, quick-growing
nutrient-rich grasses (such as winter wheat
and rye grass) can be grown and then dug
into the soil before planting.
Benefits of Compost for Healthy Soils
Compost, a natural “compote”, is a
mixture of decayed organic (once-living)
materials. Compost is known as gardener’s
gold because it improves soil structure,
retains water, encourages root growth,
aerates soil, releases nutrients slowly,
supports beneficial microorganisms and
earthworms, and suppresses some soil-borne
diseases.
Peat Moss as a Soil
Amendment Option
Peat moss is plant debris
that
has
partially
decomposed under water,
without oxygen, in wetland
ecosystems known as bogs.
Peat moss is a source of
organic matter, but does
not contribute the same
variety of nutrients as compost. Peat moss is
useful as a soil amendment which aerates
clay soil, binds sandy soil, and absorbs
water.
Because of the extremely high water
retention capacity of peat moss, it should not
be used as a top dressing. If peat moss dries
out on the surface of the ground, it may
crust over and shed water rather than
absorbing it.
Amending Soil with Shredded Leaves
or Bark
When woody materials such as
shredded leaves or shredded bark are mixed
directly into the soil, they gradually
decompose. In the decomposition process,
the carbon-rich woody material uses nitrogen
from the soil, possibly depleting the soil of
essential nitrogen for plant growth. To offset
this nitrogen loss, some gardeners mix in
nitrogen fertilizer or grass clippings with the
shredded leaves.
Would you like additional information?
Additional information is available on-line. Please see MSU Extension-Oakland
County’s publications as well s MSU Extension Bookstore on campus.
Contact our Plant & Pest Hotline (248/858-0902) for assistance with plant
identification, pests and diseases, weeds, trees and shrubs, lawn, flowers,
fruits, vegetables, grasses and groundcovers, native plants, plant propagation,
and many other gardening topics.
Distributed by MSU Extension-Oakland County, 1200 N. Telegraph Road, Pontiac, MI 48341, 248/858-0880,
www.msue.msu.edu/oakland, Reviewed & revised, by Charlene Molnar, May 2011
MSU is an affirmative-action equal opportunity employer. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height,
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