From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture
Subject: Re: mycorhiza
Date: Sun, 9 Feb 1997 16:04:54 +0000

In article <5dkp37$p88$1@nova.thezone.net>, Paul Stewart C/O ABIOGEN
<stewart@peinet.pe.ca> writes
>In article <19970206070601.CAA24439@ladder01.news.aol.com>,
>   brateaver@aol.com wrote:
>>The fact that you consider mycorrhizae as soil conditioners indicates that
>>your knowledge is at fault, not the product. Mycorrhizae are a natural and
>>practically universal adjunct to soil/roots.

[NB brateaver@aol.com is happily in my kill file.]

>I think it is far from false to suggest that addition of a
>naturally-occurring substance to a damaged soil constitutes
>conditioning. Far too much is made of the distinction between "organic"
>or "natural" and "chemical" or "artificial". 

Agreed.

>The problem with the artificial fertilizers and pesticides used today is the 
>effect that the unavailable nutrients, strong salts, and toxic additives and 
>heavy metals have on the soil microflora (read here both mycorrhizal
>fungi and beneficial bacteria). 

Generally one should differentiate between mineral fertilisers and
pesticides. The latter can alter soil microflora, some indeed are
designed to do just that. Doubtless Torsten can give a whole list of
examples. 

On this farm, personally, I note that we now have moles feeding in
arable fields where they were previously unknown. This is almost
certainly due to the considerable increase in earthworms that is
presumably due to the increase in microflora consuming the substantial
increase in crop residues (including roots) indicated by the increase in
soil organic matter. Few fields have had dressing of organic manure, and
then at low application rates. The increase in soil OM has been due to
the huge increase in crop yield that has resulted from the use of
mineral fertilisers and pesticides.

Go figure.

>A practically sterile soil with a hardpan layer 
>consisting of undeteriorated hydrocarbons

We talking about coal here? Or what?

> is not going to have the required 
>microflora to support life, without addition of the same ingredients that 
>caused the trouble in the first place. Mycorrhizal inoculants offer PART of 
>the solution to this, PART of a program of bioremediation that is required to 
>practice sustainable agriculture. What's wrong with giving nature a helping 
>hand, on her terms?
>
>Of course, offering a minimal mix of 4 or 5 mycorrhizal species as spores in a 
>mix of peat moss is practically useless BY ITSELF, and anyone selling a 
>product under these terms is offering a scam. But the tool is only as good as 
>its user. There are uses for these products. Ask any forestry scientist. 

Mycorrysal innoculants can be of use where a crop type has never been
grown before, and wild species do not exist at even very low level
naturally. One thinks of nitrogen fixing bacteria (yeah I know, not a
fungus) for lucerne in the UK as an example. However many root
mycorrhysal symbiotes are beneficial, and often required, for crops to
absorb appreciable quantities of some nutrients (phosphorus being the
usual example). Fortunately they seem to appear spontaneously when the
crop is grown. Given the wide dispersal of fungal spores and their
profligate production this is hardly surprising. Unfortunately this also
applies to the root damaging fungi, and other microparasites of crops,
fungi and indeed, all life. Personally, except in exceptional
circumstances, I wouldn't bother to buy them. Nature provides them for
free.

-- 
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"