Healthy soil and sustainable growing

[Gail Hoskisson <moabgail@frontiernet.net>]

Here's an essay on how organic agriculture would sequester and thus reduce
CO2 in the atmosphere if universally adopted in the U.S.

    CARBON SEQUESTRATION THROUGH ORGANIC AGRICULTURE

    by Richard Lance Christie

The Rodale Institute has been conducting a long-running comparison of
organic versus chemical-input cropping systems.  They have found that
organic agriculture stores so much more carbon in the soil that:

•    If only 10,000 medium sized farms in the U.S. converted to organic
production, they would store so much carbon in the soil that it would be
equivalent to taking 1,174,400 cars off the road or reducing driving by
14.62 billion miles.

•    Converting the U.S.'s 160 million corn and soybean acres to organic
production would sequester enough carbon to satisfy 73 percent of the Kyoto
targets for CO2 reduction in the U.S.

•    U.S. agriculture as currently practiced emits a total of 1.5 trillion
pounds of CO2 into the atmosphere each year.  Converting all U.S. cropland
to organic management would not only eliminate this carbon dioxide
emission, but would result in a net increase in soil carbon per year of 734
billion pounds.

The Rodale Institute's carbon sequestration research may be viewed at:
<http://www.newfarm.org/depts/NFfield_trials/1003/carbonsequest.shtml>

How is this achieved?  The essence of organic soil management is to
increase the carboniferous material and thus the density and diversity of
soil biota in the soil.  In a healthy agricultural soil ecosystem, in a
teaspoon (one gram dry) of soil one will find:
•    100 million to one billion bacteria
•    several yards of fungal hyphae
•    Protozoa: several thousand flagellates and amoebae; 100 to several
hundred ciliates
•    Nematodes: ten to 20 bacterial-feeders, a few fungal feeders and a few
predatory nematodes
And for larger organisms, in a square foot of healthy agricultural soil one
will find:
•    Up to 100 arthropods
•    5-30 earthworms, with more in soils with organic matter over two
percent.

As the soil food web decomposes organic material, it releases carbon into
the atmosphere as CO2 or converts it to a variety of forms of soil organic
matter.  Labile or active fractions of organic matter stay in the soil for
a few years.  The balance of diverse floric and faunic organisms in healthy
soil means that carbon dioxide emitted by the faunic, aerobic organisms has
a high probability of being respirated by the floric organisms for use in
forming tissue, rather than escaping into the atmosphere.

Stable forms reside in the soil for decades or hundreds of years.  Stable
carbon sequestration occurs when carboniferous (organic) matter is
protected inside soil aggregates that soil organisms create.  Humified
organic matter is stable because bacteria and fungi have helped form
molecules that are too complex and large for soil organisms to decompose
into the release of carbon dioxide.  Earthworms and arthropods consume
small aggregates of mineral particles and organic matter and generate
larger fecal pellets coated with compounds from the gut.  These fecal
pellets become part of the soil structure.  Fungal hyphae and root hairs
bind together and help stabilize larger aggregates.