mycorrhizae tolerance to fertilizer

Garry Williams gdwill at
Fri Dec 27 22:52:07 EST 1996

I have enjoyed reading this exchange, as it brings out both
information and questions, which are the keys to learning. Without
taking sides, I would like to ask a few questions about this,
especially since it's an area in which I am woefully ignorant.

egrunden at (Eric Grunden) wrote:

<I've deleted major parts of the post in the interest of brevity>

>Give people involved in agriculture some credit, very few people
>are "dumping big loads" of anything anywhere. It does not make
>economic sense, and they (for the most part) care just as much
>(if not more) about their grandchildren (whom they will most
>likely deed the land to) as you do. With the exception of nitrogen,
>any cations not taken up will lock onto a binding site until freed 
>by plant absorption.

In my state (NC) in recent years there have been a number of fish
kills in the rivers directly attributable to a nasty little
microorganism that seems to multiply in large numbers when there is
excess nitrogen in the waters, which studies have shown to come from
agricultural runoff, be it "chemical" fertilizers, hog waste or
whatever. Since fishing is an important part of the economy in our
state, this provides a clear environmental impact that directly costs
us. I mention this only in passing until we get to the questions.

>How are fields becoming less responsive to fertilizer?? Are you saying
>that plants are losing their ability to absorb nutrients? Or that
>the soil is somehow metamorphizing into something that cannot retain
>nutrient cations? Please explain.  The arguments about nutrition
>levels in organically produced versus synthetically produced fertilizers
>is the root (no pun intended) of the issue. Calling it "chemically-grown 
>food" is unscientific propaganda talk, when not discussing pesticides.

I have gathered, possibly incorrectly, that as a result of our farming
practices that the rich, loamy topsoil has virtually disappeared in
many farming areas and that this increases the need for fertilizing,
making it particularly tempting to use concentrated, low cost
fertilizers. Is this so, or have I been misled, or is this an
oversimplified view of the situation?

>$280 per 2 acres (not including shipping) and no guarentees that the
>fungus will not immediately be parasitized by other microorganisms
>upon application!  This is the problem. Urea, in which nitrogen is
>in the ammonical (not nitrate) form, costs about $210 per ton delivered, 
>which effectively treats about 10-20 acres. Couple this with a nitrate
>inhibitor like Enserv, and the environmental concerns are vitrually

Apparently the farmers in my state don't know about Enserv, or it's
not readily available, or it's too expensive, or it's not as effective
as you say, or the farmers have no economic incentive for using it or
some other explanation, but the fact remains, as I mentioned above,
that the excess nitrogen from large scale agriculture in my state is
causing serious fish kills and closing recreational areas (another
serious economic concern for my state). I would be interested in
hearing your thoughts about this situation?
>If the plants are taking up 10 times more nutrients, and you are
>not replenishing them with fertilizer, you are slowly but surely
>rendering your soil unproductive. What about the grandkids now?
>By oversapping nutrient availabilty, you have effectively turned
>your productive soil into dirt that will require large inputs of
>time and capital to replenish. As for your second point, the
>presence of a healthy mycorrhizal symbiosis causes the release
>of hormones in all plants that dramatically reduces formation of
>root hairs; they are not needed in the symbiosis.

As I understand it, organic farmers add the nutrients back in the form
of compost, manure and such, and that this works with the natural soil
processes much better than adding chemical salts. Correct or
incorrect? Explanations appreciated.

>As guarenteed and predictable as many decades of research and trials 
>can provide, and as long as soil is soil and plants are plants. It is
>not the "natural way" that plants utilize nutrients, but rather an
>evolved symbiosis that most likely occurred to deal with nutrient 
>deficient conditions, and grew from there. In most cases it has not 
>out-produced synthetic fertilizers, and using your prices it does not 
>appear to be less expensive. "Chemical program?" What chemicals are you 
>speaking of; do you mean the elements of potassium, phosphorus, etc. 
>that are the same elements regardless of source?

I'm not sure I understand your argument here. Our bodies need Na, H, O
and Cl, yet I wouldn't recommend that one try to get those nutrients
by drinking  a solution of sodium hypochlorite. Are you saying that it
doesn't matter to plants what forms the nutrients come in, that their
natural evolution has enabled them to take up nutrients in any old
form that comes along? I am asking seriously. I honestly don't know
the answer to that and would like for you to tell me, if you would be
so kind. And if you could provide a layman's view of the mechanisms
involved in the transfer of the elements that plants need, so much the

Garry Williams
 gdwill at or
 gdwill at 

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