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Soil Foodweb website



From: sam@unisun.org
Newsgroups: alt.sustainable.agriculture
Subject: Understanding Your Soil---Dr. Ingham's FREE NEWSLETTER
Date: 23 Oct 1999 05:47:23 GMT
Organization: Unisun Communications-Re: Soil Foodweb, Inc.
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************************************************
Understanding The Soil Foodweb: An Introduction  
************************************************

There are several million to billion organisms, which typically require
a
microscope to see, that live in soil and around the roots of plants. 
The
way these organisms interact with each other and with plants is called
the
Soil Foodweb. There is a best balance of all the different kinds of
microorganisms for each kind of plant to get best plant health and quite
often improve yield.  A spoonful of healthy soil should contain only
beneficial species of bacteria, fungi, nematodes and protozoa that never
cause disease or become pests. These species perform vital "functions"
in
the root zone that can bring real profits to growers IF soil conditions
are
managed in ways that allow the microbes to live and work.  To view some
of
these critters visit the link below:
________________________________________
http://www.soilfoodweb.com/gallery.html
----------------------------------------


Think about the dollar potential involved with each of the following six
functions and then be aware that these functions are entirely biological
and only occur through a soil foodweb that is built up, intact and
working!


	*******************************
	A balanced Soil Foodweb will:
	*******************************

	1. Suppress disease-causing and pest organisms 

	2. Retain nitrogen and other nutrients such as calcium,
	iron, potassium, phosphorus, etc.

	3. Make nutrients available for plant growth at the times
	plants require at the rates plants require. 

	4. Decompose plant residues rapidly. 

	5. Produce hormones that help plants grow.

	6. Produce good soil structure, improving water infiltration,
	oxygen diffusion, and water-holding capacity.
	
	7. Consume pollutants in the soil.


Disease suppression: Requires specific species of bacteria and fungi
that
compete with, inihibit and parasitize disease-causing organisms.  The
plant
uses a minimum of 25% of it's fixed energy each year to feed these
beneficial organisms in the volume of soil around it's roots.  If
pesticides or high levels of fertilizers have been used, or if plowing
has
been too intensive leaving bare soil for significant periods during the
year, these beneficial organisms are no longer present.  The exudates
the
plant makes feed disease organisms, and we see ever-increasing disease
problems.  The beneficials have to be brought back through inoculation
if
their numbers are too low, or through feeding the right kinds of foods
that
select for the "good guys", and not the bad guys.

A healthy soil that contains a broad diversity of microbial types most
often contains species that consume, inhibit or suppress the kinds of
fungi
that cause root rots and the kinds of nematodes that attack roots. There
is
plenty of research and on-farm experience to show that these economic
threats can be controlled very well without the need for applied
fungicides
or nematicides. What it takes for this to happen is good soil health in
the
form of an active, intact soil foodweb.

Retention of nutrients: Nitrate and some other nutrients can leach out
and
be lost unless they can be banked in soils until the plant needs them.
The
function of nutrient retention occurs when bacteria and fungi multiply
and
increase their populations in the soil. Bacteria and fungi are extremely
rich in protein that is made from nitrogen. When bacteria and fungi
multiply they gather nitrates, ammonium, and organic nitrogen from the
soil
and convert it to protein in their bodies. Nitrogen in this form is a
bank
account of nitrogen that does not leach easily and is not lost as a gas.
Products and cultural practices that stimulate a "bloom" of bacteria or
fungi reproductive growth can be used as tools to achieve nutrient
retention. When this function is working in your soil, half of the
process
that leads to lower rates of N and P with no reduction in crop yield is
present.  You are retaining N, P, S, Ca, K, Fe, etc, in your soil, and
they
will NOT end up in surface or groundwater any longer.  Recent studies at
SFI have shown that fungi are the most important retainers of calcium in
the soil.  Lose your fungi, and you lose the ability to retain Ca in the
soil.

Nutrient Recycling: Once nutrients have been retained, other kinds of
soil
organisms need to be encouraged to feed on the bacteria and fungi. In
bacterial-dominated soils, the rich meal of protein in the bacteria and
fungi that the predators eat is metabolized and part of the nitrogen is
released back into the soil as ammonium that is quickly converted to
nitrate for use by crops. In fungal dominated soils, since fungi produce
organic acids, ammonium remains as ammonium, and little is converted
into
nitrate.  Look at the form of nitrogen in healthy orchard or conifer
forest
soils - it is ammonium, not nitrate, that is the major form.  Forests
where
nitrate is higher than ammonium are typically in severe stress, with
dying
trees.  The organisms that release nutrients from the bacteria and fungi
(the retained form) are beneficial nematodes that only feed on bacteria
or
fungi, protozoa that feed on bacteria, and beneficial soil mites that
feed
on fungi. As these species go about their work they cause nitrogen
especially, but also phosphorus and other nutrients, to be released at a
gradual rate that supplies crops with a steady diet all season long.

Decomposition of crop residues, manure and other organic material: These
materials will only decompose if certain species of fungi and bacteria,
the
"decomposers", decay them and allow recycling processes to occur. The
ideal
process forms large amounts of humus. The decay function gets rid of
crop
residues, but what it really does is convert the food energy in fresh
organic matter to biological forms that feed other soil organisms that
do
different indispensable functions, as described below.

Production of plant growth regulators: All plants depend on the presence
of
certain species of soil microorganisms in the root zone to produce
various
hormones and other chemical "signals" that stimulate growth and
development. Two plants from the same seed, one in a dead soil and the
other in a living soil, both with the same nutrients, will show
different
rates of growth, final size and value. The plant growing in healthy soil
will have found the partnership it expects with beneficial microbes that
produce growth hormones not made by the plant itself. The plant in
healthy
soil will be the better plant.

Soil structure: In order to maintain an well-aggregated soil structure,
i.e., to improve or maintain good tilth, the organisms that glue, bind
and
engineer soil structure and soil pores must be present.  Good tilth or
good
soil structure allows optimum infiltration of air, water and roots.
Aggregates will not form unless sand, silt and clay particles are
"glued"
together by the gums and gels that many species of soil bacteria
produce.
These aggregates are further strengthened against collapse by species of
beneficial fungi that grow throughout the aggregate and physically bind
it.
The large pore spaces holding "reservoirs" of water must be built by the
larger critters, by microarthropods, earthworms, beetle larvae,
enchytraeids, etc.  The better the set of soil organisms producing
resilient structure, the more "strength" your soil has.  The more
resilient
the structure of the soil, the bigger the equipment that can be driven
on
it, without destroying that structure. 

Clean up of herbicide or pesticide carry over: Most herbicide and
pesticide
molecules can be "eaten" or degraded by certain kinds of microbes in the
soil, if those species are present. A healthy soil will tend to rid
itself
of ag chemical carry over and other forms of pollution.

Each of the functions above describes how soils are supposed to work and
can work. Your opportunity is to learn to employ cultural practices and
biological products to get all these functions working at top capacity.
Yield and profit will be the result.

Until Next Time!
Dr. Elaine Ingham
http://www.soilfoodweb.com
Questions?  Mailto:  sfi@unisun.org


You may be interested in recieving more information on the
current research projects/results and publishing
projects of Dr. Elaine Ingham.

Dr. Ingham is President of Soil Foodweb Inc. and a professor
at Oregon State University where she holds faculty status in 
Forest Science, Botany and Plant Pathology and Horticulture.  

Dr. Inham's major efforts are now in educating the public about 
the benefits of a healthy soil foodweb, which allows improved 
plant production with few, if any, inorganic chemical inputs. 
She is a widely sought-after public speaker on this subject
and travels the globe speaking as an authority in this exciting
new field of soil science.  


FREE MONTHLY NEWSLETTER!
Information on.... Soil Microbiology, Soil Ecology, Farming,
Composting, Orchards, Golf/Turf, Nursery/Landscape,
Forestry and Lawn & Garden! 

If you would like to recieve a FREE SUBSCRIPTION
to her informative monthly Email Newsletter, please place
"subscribe SFI" in the subject line of an email and send it
to:

***************
sam@unisun.org
***************

Or visit her website at http://www.soilfoodweb.com


More....

************************
Q&A Session #1
************************

Q1:
I would like to understand the mechanism of beneficial nematodes
affecting
root-feeders.  Do these beneficial nematodes survive thermal composting
cycles?

A1:
What we find is that root-feeding nematodes can be suppressed by having
a
healthy number of bacterial-feeding nematodes, fungal-feeding nematodes
and
predatory nematodes present in the rhizosphere.  "Healthy" numbers
depend
on the plant, the soil type, climate, hydrology, etc, so we expect that
the
number is different based on circumstances.  

The mechanisms for interactions between these beneficial nematodes and
the
root-feeding nematodes is something nematologists at a variety of
Universities, including my husband at Oregon State University, have been
interacting on for a number of years.  Nothing extremely formal,
certainly
not funded by any government agency that I am aware.  Right now, the
hypothesized explanations for how beneficial nematodes control
root-feeding
nematodes are:

1. Physical impediment.  The beneficials interfere with the ability of
the
pest nematodes to find the root.  This could be by occupying space along
the root so the pests don't have room to "belly up to the bar".  It
could
be that beneficials physically bump and push the pest nematodes out of
the
rhizosphere.  

2. Stimulating growth of bacteria or fungi that produce antibiotics or
other pest nematode inhibitory compounds.  When bacterial- or
fungal-feeding nematodes graze their prey, the release of nutrients
stimulates the remaining prey to grow faster.  This is a culling
phenomenon.  The stimulated bacteria or fungi may make compounds that
kill
the pest nematodes.  But in order for this mechanism to work, not only
must
the beneficial nematodes be present, but the right species of bacteria
and
fungi need to be present.

3. Inoculation of the rhizosphere with bacteria and fungi that trap and
parasitize pest nematodes.  There are many species of bacteria and fungi
that if they can gain entrance to the inside of a nematode, will cause
disease, or will parasitize the nematode.  Large numbers of nematodes -
beneficials or pests - means the diseases of nematodes will eventually
arrive too.  Maybe that's all that happens - the beneficials bring
nematode
diseases with them and trash the neighborhood, at least from the
root-feeding nematode's point-of-view.

4. Consumption of pest nematodes.  Predatory nematodes eat other
nematodes.
It's not really cannibalism, but more like people eating great apes, or
one species of spider eating another species of spider.  But the more
predatory nematodes present, the more root-feeders will be eaten.  It is
likely that some species of predatory nematodes specialize in hunting
down
root-feeding nematodes, so those would be the most effective species to
inoculate.  Which species are those?  It depends on the soil, climate,
plant species and pest nematodes present, but the best place to look for
this information is in the Journal of Nematology and to talk with your
local nematologist.   They may not know this kind of information, but
perhaps they should be encouraged to do so.

We have developed a group of beneficial nematodes that, when added to
soil,
interfere with root-feeding nematodes.  The comparison of control versus
treatments show reductions in root-feeders on addition of
bacterial-feeding, fungal-feeding and predatory nematodes.   But SFI
does
not sell products.  We test to see if nematodes are present and which
kinds
are present.  Are they the right ones, based on climate, soil type,
plant
desired, etc?  We assess whether the other organisms - bacteria, fungi,
protozoa, mycorrhizal colonization - are correctly balanced for a
healthy
soil to grow the desired plant.  But, the beneficial nematode "inoculum"
is
a product that ought to be available to growers.  Right now, SFI is
willing
to send this inoculum to people, but only if you agree to test your soil
for the nematodes present BEFORE you inoculate, add the beneficial
nematodes, and then test again in a month, and then a year later.
Basically, we're asking that you fund the necessary research to
determine
whether this inoculum will work.  We'll supply the inoculum, if you
agree
to pay for the testing.  We need at least two months notice BEFORE we
can
get started, because we have to make certain we have enough nematode
inoculum to add to what you want to test.

How much demand might there be for this beneficial nematode inoculum? 
Most
people don't realize this, but there are a number of situations where
beneficial nematodes need to be added to soil or to compost.  

1. When nematicides have been used, those chemicals kill the beneficial
nematodes as well as the pest nematodes.  It is rare that the
beneficials
come back before the pests! 

2. When pesticides are used that kill the non-target beneficial
nematodes
(such as 2,4-D, Bravo in some cases, anything containing an
alcohol-base,
dichloran, orthene, etc, etc) are used, it may be years before they
return.
Because it is not required that pesticides be tested to determine their
effect on beneficial nematodes, some pesticides likely kill only the
beneficials, and not the pest nematodes.  Consumers need to demand that
this information appear on pesticide labels.  

3. When compost gets too hot, too anaerobic, or too wet during
composting,
the beneficial nematodes are either killed or forced into dormant forms.
If killed, the beneficial nematodes need to be added back to the compost
as
soon as temperature in the pile comes back down to 100 F or lower.
Typically, if compost doesn't heat too high, the beneficial nematodes
begin
to grow at warm, but not-too-hot temperatures.  They can then fulfill
their
beneficial roles of consuming bacteria and fungi, consuming pest
nematodes
if present, improving nutrient cycling in the compost, and improving
aggregate structure in the compost (they are one of the engineers of
larger
soil pores).  If they start growing rapidly enough, they can be in high
numbers by the time the compost is mature and added to soil.  

4. Following rapid freeze-thaw, or wet-dry cycles, pro-longed anaerobic
conditions in the soil, or conditions (toxic chemical spills, fires that
heat the soil to high temperatures) that kill the beneficial nematodes.

Turning to the question about compost temperature, the data we've
collected
shows that root-feeding nematodes don't survive thermal composting very
well at all.  Root-feeders appear to be quite sensitive to temperatures
above 100 F, while numerous species of bacterial-feeders and
fungal-feeders
survive temperatures as high as 145 to 155 F.  There are probably some
species of root-feeding nematodes that survive high temperatures, but
they
don't also survive the suppressive activities of beneficial nematodes
(outlined above), and the fact that there are no roots to eat in a
compost
pile.  

A very important point with composting is if you go over 155 to 160 F,
the
only nematodes that survive are the ones that can produce dormant
stages.
This is a very limited set of nematodes and diversity suffers
excessively
when compost gets too high in temperature.  Lack of diversity means you
won't have the right beneficial nematodes to suppress, inhibit or eat
the
pest nematodes given all the diverse set of environmental conditions
present through the course of a year.  Most ecologists are very
cognizant
that any one particular species of organism is active and doing it's
things
only during a limited set of conditions.  Some species require low
temperature, others high, others need high humidity, others low, some
like
certain kinds of bacteria to eat, others find those same bacteria toxic,
some like high iron, others need low, and so on.  Thus, to have active
beneficial nematodes through the whole year, you need as wide a
diversity
as you can manage.  Thus, reducing that diversity by getting the compost
too hot reduces the chances of having the diversity of species needed to
combat the pest species.

When we might add an inoculum of beneficial nematodes to improve
diversity,
we aren't really certain what the best time is for adding that inoculum.
In compost, beneficial nematodes appear to be happy even when the
temperature is 145 F, but they were in the compost from the beginning of
the heating cycle, not added to the compost.  Going from ambient
temperature in an inoculum to 145 F in the compost might kill the
nematodes
without some period of acclimation.  The beneficial nematodes that were
in
the compost to begin with are of course acclimated to the heat.   But it
leaves a question about when is the best time to add an inoculum of
beneficial nematodes.  We need to start adding at say 100 F, and if all
of
the added nematodes survive that temperature, then we try adding them to
the next compost at 110 F.  If they all survive that, then we try 120 F,
and so on.  

So, stay tuned.  When we get that figured out, we'll post it on the web
site.



**************************************************************************
If you find the information you have just read valuable, you may be
interested in
a new CD Audio Lecture Series by Dr. Elaine Ingham:

Unisun Communcations is proud to announce the release of....

Dr. Elaine Ingham Talks on the Soil Foodweb---An audio CD Lecture
Series.

The first in the series of 8 lectures is "An Introduction to the Soil
Foodweb" and is now available!


These are not live recordings.  All of the CD's are recording in a state
of the art digital recording studio and are of the highest quality.
Diagrams accompany the CD on the inside jacket.


*****************************************************************
CD Series #1--"An Introduction to the Soil Foodweb" NOW AVAILABLE
-----------------------------------------------------------------
Dr. Elaine Ingham discusses the important functional groups of organisms
that live in soil, how and why they enhance plant growth and production.
This is the introductory talk about the Soil Foodweb. All other CD's
assume
an understanding of this introductory material.

Included in this Double CD set:
        -The seven benefits of a beneficial soil foodweb.
        -Who starts the process? Soil organisms or plants?
        -Disease suppression: Working together.
        -Nutrient retention: Bacteria and Fungi
        -Production of plant available nutrients: Protozoa, nematodes
         and microarthropods
        -Getting rid of toxic compounds.
        -Soil structure: Bacterial bricks, fungal walls, protozoan,
         nematode and microarthropod engineers.
        -Some considerations about plant health


*************************************************************
CD Series #2--"The Soil Foodweb: A Plant Production Overview"
-------------------------------------------------------------
This talk explores the effect chemically intensive agriculture has had
on
soil life, why pesticides are effective initially, but with continued
use,
result in the destruction of beneficial soil life, with direct negative
impacts on sustainable agriculture.  


Included in this Double CD set:
	-What is soil?  Parent material?  Dirt?
	-The plant production gradient and succession
	-Soil foodwebs in different systems: What's different in
	 deserts versus tropical forests?
	-From deserts to grasslands to old-growth: Biomass, numbers of
	 individuals, number of species of each soil foodweb functional group. 
	-Agriculture: How did we get to where we are today?
	-Why does improving the foodweb in degraded soil mean increased yields?
	-Different crops require different foodwebs for best production:
	 Examples from agricultural fields and orchards.  
	-Summary

This CD Series is currently in production and will be available by
November 10th, 1999.  Orders are now being taken.

For more information, to order, and to even PREVIEW these CD's please
visit http://www.soilfoodweb.com or visit us at
http://www.unisun.org/artists/ingham
For More info--Contact Unisun 541-367-8980 or SFI 541-752-5066

-- 
Lawrence F. London, Jr.  Venaura Farm
http://metalab.unc.edu/ecolandtech/landcare.html  
/intergarden /permaculture /permaculture-online
lflondon@mindspring.com  london@metalab.unc.edu