From: dc_ags@ac.nsac.ns.ca (Don Christie)
Subject: Re: Returning nutrients to the soil
Reply-To: dc_ags@ac.nsac.ns.ca
Organization: Nova Scotia Agricultural College, Nova Scotia, CANADA
Date: Wed, 18 Nov 1992 18:09:43 GMT

>>It must be added that in a naturally occuring ecosystem "exotic" toxins
>>or foreign trace elements as probably occur only metres away as thousands
>>of miles. For that matter, many trees will actually drip toxins onto the
>>understory to kill it in competing for the local soil nutrients.
>
>Good point...that's something to be considered.
>

these chemicals are called phytoalexins... their very existence was the topic
of hot debate for years... now they are generally accepted to exist, and in
fact some researchers are investigating the possibilities of exploiting
them.

>>It is not a problem how plant nutrients are packaged;
>
>Yes it is.  If they're supplied in the natural form, they support the entire
>local ecosystem, e.g., soil microbes, not just the plants themselves.  If you
>just supply highly available nutrients, you're feeding the plants only.  This
>leads to reduced levels of microbes in the soil, which reduces the soil's
>ability to convert indigenous minerals into nutrients.

this is basically true: the microbial population in soil is largely responsible
for the cycling of important nutrients... especially the N-P-K types. 
However, it would be an error to discount the effects of inorganic chemical
reactions which are responsible for the availability of some nutrients in
the soil solution. In this regard, soil pH is a critical factor... nutrients
may be available in abundant supply, but if the pH of the soil environment is
too high or too low, then plants cannot absorb them. Soil testing allows a 
person to assess the current nutrient status in a given soil, and its pH. 

In many places, soil testing is provided as a service free of charge 
(it is here in N.S.) to anybody. Based upon the results of such an analysis, 
it is possible to determine whether, and if so how much, nutrient to apply 
to bring the soil to an optimum level. Exogenously applied nutrients cause 
their most damage to soil microbial activity when they are used in excess 
of the requirement of the crop. What I am suggesting is merely a 
middle-of-the-road approach to nutrient management....

>
>>You might well ask, "How does your garden grow?", before listening to
>>what anyone has to say in any event . . .
>
>There are at least two schools of thought on this.  One, apparently yours,
>believes that the intimate details need to be understood before something can
>be mastered.  The other, mine, agrees that it might be possible to do that, but
>that it is not necessary.  It is often the case that processes can be managed
>by taking care of the big picture and letting natural processes take care of
>the details.

take this argument and put it into a different context... it might make a bit
more sense... for example, let's examine two individuals who wish to learn
to play a musical instrument... a guitar.

Individual A decides that the best approach to this subject would be to go
to a music conservatory and learn musical theory. Individual B doesn't agree,
and simply picks up the instrument and learns to play by ear.

In time, both individuals will undoubtedly learn to play guitar... but the 
answer to the question of which musician is better depends on your point of
view. Individual A has the opportunity (by virtue of superior knowledge) to
adapt to and play virtually anything... Individual B on the other hand will
(because of a lack of knowledge) be closed off from a broad segment of his/her
craft. 

The same holds true for agriculture. In order to perform adequately as a farmer
in modern society, he/she requires in-depth training on a wide variety of
topics... ranging from basic chemistry and biology up to and including
economics and other forms of mathematics. It is still possible to undertake
farming without this knowledge, (as it was possible for the guitar player to
play without music theory), but it is much more difficult to `get it right'
because of a lack of knowledge. 

this argument is especially valid in the context of a COMMERCIAL FARM, where
the consequences of an inappropriate decision are much more severe than those
experienced by a home gardener.... 


//Don
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