Mike Travis, Pepin County Agriculture Agent

February 2015

Growing Healthy Soil

WHAT IS HEALTHY SOIL?

Healthy soil is NOT a sterile growing medium—it is

teeming with life. In a moderately-sized garden there may

be over 100 lbs. of living creatures UNDER the surface!

A single teaspoon of soil may contains:

A billion bacteria

Thousands of protozoa

Dozens of nematodes

Several yards of fungal filaments

In addition to the microorganisms, residents of healthy soil

include earthworms, insects, spiders and springtails. The

soil’s vibrant community works together to build the rich

environment needed to grow healthy plants.

HOW DO I GROW HEALTHY SOIL?

Really, it’s quite simple. In fact, it is how healthy soil is

formed in a natural environment such as a forest or prairie!

Often our activities disrupt the soil ecosystem’s quest for

health. Here are four key principles to growing healthy soil.

FIRST: Do not disturb. This might be hard for those of us

who love to till soil! But by not tilling, we encourage the

natural, healthy development of the soil, which actually

includes natural tillage by the earthworms!

SECOND: Keep it covered. Mulches such as straw, leaves

or compost help manage weeds, conserve moisture, buffer

temperature extremes, and are a source of future organic

matter and food for soil organisms—who in turn feed our

garden plants. A living cover crop can also be your mulch—

which brings us to the third principle.

THIRD: Maintain a living root. Roots of living plants

provide a cozy home and food for many of the soil’s micro-

residents. Besides your main crop, a cover crop planted

between rows or in the fall helps to keep the soil alive and

healthy all year.

LASTLY: Grow a variety of crops. In a garden of course

that is what we do. Make sure to change where you plant

crops from year to year. Where you have wide row spaces,

or when a crop is finished, plant a cover crop. Rotation of

crops and use of living cover breaks pest cycles and

encourages a rich diversity of health-promoting creatures.

HOW DO I START?

Start small. You may want to begin with a portion of your

garden dedicated to learning to grow healthy soil.

Follow the principles. Experiment with the four principles

of soil health. Observe the results, and adapt as needed.

Plant a cover crop. Rye is great fall cover because it will

continue to grow late into winter. Oats and radish grow

quickly and are easy to manage in the spring because they

die over winter to provide new mulch. Learn about

different cover crops and find what works best for you.

Don’t get discouraged. It can take several years before you

see the full benefits of soil health principles. Keep at it and

the soil’s residents will reward you!

As gardeners we think about how to grow healthy

vegetables and fruits, but do we think about

how to grow healthy soil?

For more information, contact your

local UW-Extension Office

A fall cover crop

Mike Travis, Pepin County Agriculture Agent

February 2015

Soil can be described by four main components—mineral,

air, water, and organic material. Mineral particles (i.e.,

sand, silt, and clay) along with the addition of a relatively

small portion of organic matter, provide the basic structure

of most soil. The spaces created by this framework are

occupied by water and/or air. But soil is so much more.

The organic matter fraction consists of: 1) humus (organic

matter in various stages of decomposition), 2) living roots

of above ground plants, and 3) soil-dwelling organisms.

This organic fraction organizes soil into a complex

ecosystem of interdependent networks.

It has been estimated that over 10,000 different species of

bacteria, fungi, protozoa, nematodes and other organisms

are present in a sample of soil. These soil residents

together with plants growing in the soil serve various roles

in managing the soil’s air, water, and nutrient resources.

Consider that—

Plants:

Exude compounds that feed and nourish microbes;

Provide habitat for the microbial residents;

Naturally till and aerate soil;

Protect the soil from wind and water erosion.

Soil organisms:

Supply minerals to plants;

Fix nitrogen for plant use;

Breakdown organic matter and recycle nutrients;

Stabilize soil structure with glomalin “glue”;

Suppress plant diseases.

Understanding Soil & Soil Health

Is my soil healthy?

Look at the soil. Healthy soil

is dark. This is the richness of

organic matter, which is the

foundation of healthy soil.

Feel the soil. Is the soil soft

and crumbly or hard and

massive? A healthy soil is

soft yet stable; it will

crumble into aggregates—

groups of mineral and

organic particles bound

together by biological

glues—which resist

disintegration.

Look in the soil. The presence

of earthworms, springtails,

sowbugs, and other creatures

indicate a vibrant, healthy soil

ecosystem.

Smell the soil. An

earthy aroma (the

same smell you

sometimes notice

when a rainstorm

approaches) indicates

that beneficial

microorganisms are active. Geosmin is the compound

responsible for this aroma. If there is little or no smell,

there is little life in the soil. A sewer-like smell tells you

the soil is starved for oxygen—perhaps from

compaction or being waterlogged.

How can I tell if my soil is healthy? Indicators of soil health

are described in the box below. How do I improve soil

health? To improve soil health, we must improve the soil’s

biology. To do this, a good environment must be provided

for soil organisms, and they must be fed. Four steps to

growing healthy soil are given on the other side of this page.

“To be a successful farmer one must first know the nature of the soil.” Xenophon, Oeconomicus circa 362 B.C.

Soil Health

“The continued capacity of soil to function as a vital living

system, within ecosystem and land-use boundaries, to sustain

biological productivity, promote the quality of air and water

environments, and maintain plant, animal, and human health.”

Pankhurst et al., 1997