From waldenfarm@sprintmail.com Mon Oct 11 22:30:53 1999
Date: Mon, 11 Oct 1999 12:21:40 -0400
From: Alex McGregor <waldenfarm@sprintmail.com>
To: "sanet-mg@shasta.ces.ncsu.edu" <sanet-mg@shasta.ces.ncsu.edu>
Subject: Re: Organic and nutrition

There's been a lot of questions and answers on this thread. Maybe my
limited knowledge of the subject would help some.

At the Southern SAWG Conference in Memphis about 2 years ago, a farm
consultant did a demonstration of Brix testing- measuring the amount of
sugar in fruit with a refractometer; there is a direct correlation
between sugar content and mineral content. So, the higher the sugar, the
higher the mineral content.

He had an organically grown yellow squash he bought that morning from a
health food store and a chemically grown one from a supermarket. The
chemically grown squash had a much higher sugar content and thus,
mineral content. The crowd was perplexed. People around me were mumbling
that it couldn't be right because, "Everybody knows organic has a higher
nutritional content."

What this showed was that the chemical farmer had a better mineral
balance in her/his soil than the organic farmer- by luck or effort, we
don't know. (The factor not measured here was the amount of toxic
chemicals and metals in the squash.)

There are 2 basics facts about minerals in the soil and plant uptake
that we just can't ignore:
1.) If the soil doesn't contain the mineral, plants can't take it up.
(Pretty obvious.)
2.) If there is too much of one mineral, it will suppress the uptake of
other minerals by     plants. (For example, excessive calcium in a soil
will block the uptake of iron, even if there is sufficient iron in the
soil.)

That's the chemistry part of soil. But there is another factor we know
less about- the biology of the soil. What we do know is that where you
have low levels of minerals and a high soil biodiversity (through good
soil management practices and sufficient organic matter), the plants
have higher mineral content. This happens through having a large
population of plant nutrient cyclers and plant symbionts present in the
soil, making the scarce minerals more available or "feeding" them
directly to the plants.

This soil biology can also "buffer" the mineral imbalances and the
uptake of heavy metals. Plants will also take up non-nutritive ions
(i.e., heavy metals and other ions) and can substitute these for plant
nutrient minerals to survive.

So, those organic farmers who pay attention to good management practices
for their soil and maintain an adequate food source for their soil
biology (organic matter) produce higher nutritional quality food than
organic farmers who don't. And non-organic farmers who practice good
soil management, balance the minerals in their soil and add organic
matter do better than either on mineral content. (Given the same soils
and the condition that the chemical farmer is not destroying the soil
biology.)

And, an organic farmer following the same practices of soil management
and mineral balancing can do as well or better than the non-organic
farmer for nutrient content without the chemical residues.

There are areas of our country where recent geologic events (glaciation
in the Midwest, volcanic in Hawaii, fault zones on the West coast and
Middle Tennessee) have remineralized the soils naturally and where
plants have access to minerals. Then there are zones where temperatures
and high rainfall have depleted the soil minerals (Southeast US, with
the exception of fault zones).

So, the soil type and history has a lot to do with plant nutrition. But,
we can boost the organic matter and add minerals in a balanced way to
convert minerally "poor" soils to produce minerally "rich" crops.

How to balance minerals is another story. I think I've been going on
long enough.

By the way, I have been impressed with how many sanetters have an
appreciation for, and knowledge about, this subject. I share Bart's
experience about, "...the overwhelming majority of organic farmers don't
'get' this any better than their conventional colleagues..." I have yet
to meet another organic farmer in the Southeast who uses some form of
mineral management beyond NPK- and this is a geographic area where it is
so critical for plant and human nutrition!

Alex


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