mycorrhizae tolerance to fertilizer

don at don at
Wed Dec 18 09:07:10 EST 1996

Eric Grunden wrote:
> In a previous article, brateaver at () says:
> >And it is not correct that there are not adequate supplies, etc. of
> >mycorrhizae cultures. There are plenty of sources now, both endo and ecto
> >types. All those arguments you gave are incorrect. There is now no reason
> >at all for not getting the cultures and using them, regardless of scale.
>                                 ********
> OK. Out here in rural IL farmers have their choice from a couple of
> thousand different places to go purchase fertilizer, most of which
> will deliver the proven product to their door. Please tell me where
> they should go to purchase their mycorrhizae, what equipment they should
> use to apply it, how much it costs per acre to use and apply, and
> the proven results they can expect under a variety of soil, climatic,
> and environmental conditions, and I'll pass the word along to them.....
> --
>                         *******************
> The Spirit of Nature, a powerful force,
>         belongs and returns to its creative source.
> - Excerpted from The Collective Works of Johnny Pokerface -

Eric - I don't exactly sense a real serious interest on your part, but
noted your posting and will respond to it.  

First, about the "proven" fertilizers, no one can deny that crops can be
grown by short-cutting the natural process of plant nutrition (through
conversion of organic matter and mineral elements by bacteria, fungi,
earthworms, etc.).  You absolutely can direct-feed plants with synthetic
NPK.  But forever?  The big question for all of us is whether dumping on
big loads of NPK is a sustainable practice.  How will those fields
produce for our grandchildren?

Some fields are becoming less responsive to fertilizer and input costs
are rising.  A lot of the applied nitrates wash through the root zones
and end up in the aquifer.  Severe salt build-up is taking place along
the Colorado.  These are probably the main economic-related concerns. 
I'll leave the arguments about nutrition levels in organic versus
chemically-grown food to others.

My company sells mycorrhizae inoculant, with the dormant spores of
several widely-adapted species in a dry granular base.  It can be
scattered on fields in a variety of ways, including by plane, and then
disked into the soil.  Rates vary according to the crop, but a gallon or
two per acre is all that is required.  Our price is $75 per gallon, or
$280 for a 4-gallon bucket.

However, if a grower is going to persist in creating luxury levels of
fertilizer (organic or inorganic) in the soil, he might as well not
apply mycorrhizae.  When plants have abnormal levels of nutrients
available, they reject the mycorrhizae.  With mycorrhizae, perhaps only
one-quarter as much fertilizer will be needed, but it must be a
low-analysis gradual-release type to avoid destroying the mycorrhizae.

As just one little example, a local Master Gardener had been growing his
home tomatoes with granular fertilizer for decades.  This past summer,
he grew a Roma tomato his normal way and got 47 full-size ripe
tomatoes.  Pretty good - 4 dozen from a single vine.  I asked him to
also grew one without adding fertilizer - he just used a teaspoon of
mycorrhizae inoculant.  That one vine produced 181 full-sized tomatoes,
over 15 dozen, and also began ripening two weeks earlier.  

This is not some mystery snake-oil soil additive, it's simply using good
biological science.  Plants uptake ten times or more nutrients though
mycorrhizae as they can with only their roots!  Some types of plants,
such as citrus, have become so dependent on mycorrhizae that they have
lost most of their hair roots.  

Asparagus is another good example of a thick-rooted plant that is called
a "Heavy feeder".  Nonsense, it just needs mycorrhizae to be out
searching the soil for food and moisture.  Otherwise, you have to keep
high levels of nutrients snugged against its few big roots. 

Now, I know that folks like you and most of the ag university people
have been raised with the notion that plants need feeding.  You do your
soil tests, adjust the pH level, and add tons of NPK fertilizer.  On one
level, this direct-feeding works.  But it sure screws up the soil
critters that would normally provide free nutrients and protection for

Guaranteed, predictable results?  You may feel you have that now, but
for how much longer?  A bio-organic approach is a lot more than
spreading manure, it deals with the natural way that plants uptake
nutrients and can out-produce chemical methods at less expense.  But NOT
as just an add-on to a chemical program - it has to be INSTEAD OF a
chemical program.  

I grew up on a grain farm in Oregon.  I'm a lifetime gardener and fruit
grower.  Believe me when I say you'll be reading and hearing a lot more
about the commercial use of mycorrhizae in the next few years.  This is
exciting stuff!

Best regards,

Don Chapman
Bio/Organics Supply Center
Camarillo CA

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