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  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Soil: The Roots of Sustainable Agriculture
  • Date: Thu, 12 Oct 2006 09:40:28 -0600


Soil: The Roots of Sustainable Agriculture
John Ikerd
Professor Emeritus, University of Missouri
http://www.ssu.missouri.edu/faculty/jikerd/papers/SFTsoils.htm


All life is rooted in the soil. All living things, including humans, need
food of one kind or another. Life also depends on air and water, but
nothing can live with air and water alone. Living things not directly
rooted in the soil – things that live in the sea, on rocks, or on trees,
for example – still require minerals that come from the earth. They must
have “soil” from somewhere. Living things other than plants get their
food from plants or from other living things that feed on plants, and
plants feed on the soil. By one means of another, all life is rooted in
the soil. The purpose of a sustainable agriculture is to sustain human
life, and thus, sustainable farming must be rooted in the soil.

I am an economist, not a soil scientist. So, when I talk about the soil, I
try to stick to the things that almost anyone might already know or at
least can understand. As I was doing some reading on the subject of soil,
I ran across a delightful little book, “The Great World’s Farm,”
written by an English author, Selina Gaye, somewhere around the turn of the
20th century. Back then people didn’t know so much about everything, so
they could get more of what they knew about a lot of different things into
a little book. The book begins by explaining how soil is formed from rock,
proceeds through growth and reproduction of plants and animals, and
concludes with cycles of life and the balance of nature. The book stresses
throughout that all life is rooted in the soil.

Initially, molten lava covered all of the crust of the earth. So, all soil
started out as rock. Most plants had to wait until rock was pulverized
into small particles before they could feed on the minerals contained in
the rock. Chemical reaction with oxygen and carbon dioxide, wearing away
by wind and water, expansion and contraction from heating and cooling, and
rock slides and glaciers have all played important roles in transforming
the earth’s crust from rock into soil. However, living things also help
create soil for other living things.

Lichens are a unique sort of plant that can grow directly on rock. Their
spores settle on rock and begin to grow. They extract their food by
secreting acids, which dissolve the minerals contained in the rock. As
lichens grow and die, minerals are left in their remains to provide food
for other types of plants. Some plants feeding on dead lichens grow roots
capable of penetrating crevices in rocks caused by weathering. Growing
roots can split and crumble rock further, exposing more surfaces to
weathering and accelerating the process of “soil making.”

Specific types of rock contain limited varieties of minerals and will feed
limited varieties of plants – even when pulverized into dust. Many
plants require more complex combinations of minerals than are available
from any single type of rock. So the soils made from various types of
rocks had to be mixed before they would support the variety and complexity
of plant life that we have come to associate with nature. Sand and dust
can be carried from one place to another by wind and water, mixing with
sand and dust from other rocks along the way. Glaciers have also been
important in mixing soil. Some of the richest soils in the world are
fertile bottomlands along flooding streams and rivers, loess hills that
were blown and dropped by the wind, and soil deposits left behind by
retreating glaciers.

Quoting from “The Great World’s Farm,” “No soil is really fertile,
whatever the mineral matter composing it, unless it also contains some
amount of organic matter – matter derived from organized, living things,
whether animal or vegetable. Organic matter alone is not enough to make a
fertile soil; with less than one-half percent of organic matter, no soil
can be cultivated to much purpose.” After the mixed soil minerals were
bound in place by plants, and successions of plants and animals added
organic matter and tilth, the mixtures became what we generally refer to as
soil.

The first stages of soil formation are distinguished from the latter stages
by at least one important characteristic. The initial dissolving,
grinding, and mixing required millions of years, whereas, soil binding and
adding organic matter can be accomplished in a matter of decades. Thus,
the mineral fraction of soil is a “non-renewable” resource – it
cannot be recreated or renewed within any realistic future timeframe.
Whereas, the organic fraction is a renewable or regenerative resource that
can be recreated or renewed over decades or at least over a few
generations. Misuse can displace, degrade, or destroy the productivity of
both fractions of soils within a matter of years. And, once the mineral
fraction of soil is lost, its productivity is lost forever.

If there are to be productive soils in the future, we must conserve and
make wise use of the soils we have today. The soil that washes down our
rivers to the sea is no more renewable than are the fossil fuels that we
are mining from ancient deposits within the earth. In spite of our best
efforts, some quantity of soil will be lost – at least lost to our use.
Thus, our only hope for sustaining soil productivity is to conserve as much
soil as we can and to build up soil organic matter and enhance the
productivity of the soil that remains.

In times not too long past, the connection between soil and human life was
clear and ever present. Little more than a century ago, most people were
farmers and those who were not lived close enough to a farm to know that
the food that gave them life came from the soil. They knew that if the
soil was rich, if the rains came and the temperature was hospitable to
plants and animals, food would be bountiful, and there would be plenty to
eat. They knew that when droughts came, plants dried out then died, the
soil was left bare, and there was little to eat. They knew when the floods
came, plants were covered with water and died, the soil was left bare, and
there was little to eat. They knew very well that their physical
well-being, if not their lives, depended on the things that came from the
soil.

Today, the connection between soil and life is no less critical but is no
longer so direct or so clear. Most urban dwellers also have lost all sense
of personal connection to the farm or the soil. During most of the past
century many people living in cities either had lived on a farm at one time
or knew someone, usually a close relative, who still lived on a farm.
Their connection with farming gave them some understanding of their
connectedness with the soil. At least they knew that “land” meant
something more than just a place to play or space to be filled with some
form of “development.” But these personal connections have been lost
with the aging of urbanization. One of the most common laments among
farmers today is that “people no longer know where their food comes
from.” For most, any real understanding of the direct connection between
soil and life has been lost. It’s sad but true.

Still, all of life depends upon soil. All life requires food and there is
simply no other source of food except living things that depend directly or
indirectly on the soil. Farmers are the living beings who care for the
land, plant the seeds, and nurture the life that springs from the soil.
This foundational principle of natural science, of human health, and of
social studies should be taught at every level in every school in the world
-- beginning in kindergarten and continuing through college. The
connection between healthy soils and human health and life is as
fundamental as our connection with the air we breathe, the water we drink,
and the food we eat. It’s just less obvious.

Quite possibly, no aspect of education is more critical to the
sustainability of human life on earth than is a broad understanding of the
critical linkage between the health and life of soil and the health and
life of humans. A sustainable agriculture is but the means by which life
is brought from the soil and by which the health of the soil is sustained
to support future human life. Even the economic and social dimensions of
sustainability may be best understood in terms of ecological principles
connecting people with the earth in a web of life. Many students may not
be particularly interested in farming, but everyone can relate to food and
everyone experiences the earth.

Recently, I was asked to participate in a discussion of future directions
for soils programs of the University of Missouri. Some of us suggested
that future research and education programs should focus on creating a
better understanding, among students and the public alike, of the critical
linkages among soil health, human health, and societal health. As
scientists have focused ever more narrowly within their respective
disciplines, we have degraded the natural productivity of our soils, have
destroyed the ability of farms to support rural economies, and have
diminished the sustainability of human society. If were are to build a
sustainable society, scientists of all disciplines eventually must address
the full ecological, economic, and social implications of their work. But,
the science of sustainability must begin with sustaining the life of our
soils – where roots of a sustainable agriculture must grow.
-----------------


paul tradingpost@lobo.net







  • [Livingontheland] Soil: The Roots of Sustainable Agriculture, TradingPostPaul, 10/12/2006

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