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Requested Info: Dr. Ingham's E-Zine...Issue #1 November, 1999
- To: london@metalab.unc.edu
- Subject: Requested Info: Dr. Ingham's E-Zine...Issue #1 November, 1999
- From: sam@unisun.org
- Date: Sun, 7 Nov 1999 16:59:43 -0800 (PST)
- Organization: Unisun Communications-Re: Soil Foodweb, Inc.
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Dr. Ingham's Talks on the Soil Foodweb
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E-Zine Issue #1 November, 1999
Greetings folks!
Here's the first issue of Dr. Ingham's E-zine. This
month she expands on the basic concepts explored in the
Intro To the Soil Foodweb letter that you received when
you signed up...
As always, we thank you for your support and any way that
you can help spread the word about Soil Foodweb, Inc. and
their work would be much appreciated...let's do link exchanges,
add a friend to our email list or get involved and send us
suggestions and articles of your own!
Reminder: Dr. Ingham will be speaking at various locations
around the globe through the rest of 1999. For details
please visit our website http://www.soilfoodweb.com!
Did you order your copy of An Intro to the Soil Foodweb-
Dr. Ingham's new CD audio lecture series? Details at
the end of this letter!
Peace,
Samuel A. Ettaro II
Unisun Communications
Dr. Ingham/SFI Newsletter Administrator
http://www.unisun.org
sam@unisun.org
(541)367-8980
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The Soil Foodweb---Productivity
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by E.R. Ingham
The soil foodweb is important because:
Plant productivity increases as soil foodweb complexity
increases. Hidden in this simple statement is an
incredible wealth of interesting interactions, complex
feedbacks, and less-than-obvious subtleties.
In order to reduce the cost of growing row crops, herbs,
shrubs, orchards, and forests, we need to manage soil organisms.
We need to be aware that soil organisms exist, we need to know
which ones help plants grow, and which ones harm those plants.
In order to manage those organisms, we need to be able to measure
them. The soil foodweb includes the base of the foodweb cascade,
plants, those organisms that convert plant material into their
own biomass, metabolites, and respiratory products, i.e., the
bacteria, fungi, root-feeding nematodes and arthropod herbivores.
Bacteria and fungi immobilize N in their biomass, and along with
soil organic matter which these organisms produce, contain nearly
all of the nutrients in the soil. The problem is to move the
nutrients from these organisms into plant-available forms as the speed
and in the places the plants need them. Too much mineralization into
plant-available forms, and the nutrients are leached or volatilized from
the system. Too little mineralization, and the plants die. It is the
organisms that eat bacteria and fungi which turn the nutrients immobilized
in bacterial and fungal biomass into plant-available forms. Thus,
protozoa, nematodes and microarthropods, these predators of bacteria and
fungi, are critical players in plant production. But these predators can
overeat bacteria and fungi, and so those predators that eat predators of
bacteria and fungi are important in keeping balance.
Along with nutrient cycling, a complex soil foodweb keeps disease-causing
organisms in check, improves aggregation in the soil thus improving ease of
root penetration and water infiltration, and increases decomposition of a
greater variety of plant materials, and anthropogenic compounds. As a
greater diversity and a greater number of functional groups of organisms
occurs in the soil, competition with disease-causing organisms is greater.
The soil foodweb greatly influences the production of soil aggregates,
soil pores and soil channels. An analogy to building a brick house is
useful here. To build bricks, straw and sand have to stick together. Then
the bricks are held together with mortar to form walls. The house has
structure when the walls are arranged in certain patterns. Different
organism groups in the soil foodweb do the same for soil structure.
Bacteria glue the clays, silts and sands together into microaggregates.
Microaggregates are bound together by fungal hyphae, root hairs and roots.
The structure of the rooms are made by the arthropods, insects and
earthworms. Only when all the organisms are present and active can roots
and water move into the soil with ease.
Soil compaction is a major disturbance of soil aggregation. When heavy
machinery moves across the soil, the pores and channels within the soil
collapse. As the space in the soil is reduced, the organisms living in
those spaces are killed. Thus, the force applied, and the strength of the
aggregates in the soil determine the extent of damage. Like an earthquake,
damage is greater the greater the force of earth movement, and the
flimsier the construction of the building. Compaction by a 2 ton truck
will be greater than a 1 ton truck. The better the construction of the
aggregates, the less damage is wreaked on the soil. One way of looking at
this is to say, if a highly complex soil foodweb is present, better built
soil aggregates will be present, and the bigger the truck is that can be
driven on the land. Alternatively, an assessment of the soil type and the
soil foodweb should yield an understanding of how fragile soil structure
is, and thus what kinds of vehicles can be used without destroying
critically important functions in that soil.
Clearly, we can't yet quantify an index of soil aggregate fragility, but
what information exists allows the following conclusions to be made:
1. The biggest organisms are most susceptible to compaction. The biggest
organisms tend to be the top of the foodweb, those organisms that keep the
correct balance in the system. When these organisms are lost, at least
theoretically, the soil will switch from a fungal-dominated to a
bacterial-dominated system. When soil becomes dominated by bacteria, trees
cannot grow.
2. As compaction continues, soil pore space decreases, killing the largest
of the predators of bacteria and fungi. Since fungal-feeding predators are
larger than bacterial-feeding predators, fungal-feeding organisms are lost.
This means fungal biomass accumulates, preventing release of nutrients
tied-up in fungal biomass. Plants may suffer nutrient deficiencies, since
nutrient cycling is blocked.
3. As compaction reduces soil structure even more, bacteria, protozoa and
opportunistic fungi are about the only organisms that remain active in the
soil. Roots and water have a difficult time moving into and through the
soil. Root -feeding nematodes and insects have no or few competitors. When
the soil wets-up, oxygen diffusion is limited since the soil pores are
small and passage between them is limited. These are perfect conditions
for fungal pathogens to grow, since they too have little competition.
Bacterial growth continues, however, and anaerobic conditions can develop
as oxygen diffusion is slowed. Anaerobic bacteria produce metabolites
which are extremely detrimental to root-growth, with direct impacts on
plant production.
Once soil is compacted, there are two situations that need to be
considered. If compaction is minimal, it is best to add some food for the
organisms and let the organisms recover. As the organisms recover, they
re-form aggregates and improve soil structure. There is a balance between
the amount of food to add, the type of food to add, and the rapidity with
which the organisms can respond. For example, if too much simple food is
added too quickly, the bacteria will grow rapidly. Depending on water
status, the bacteria can either use up soil oxygen and produce anaerobic
conditions, or immobilize soil N, and limit plant growth.
Is "decompacting" the soil by sub-soiling a good idea? If the organisms
haven't been lost, sub-soiling can decrease the time until the larger
organisms return. But sub-soiling can add insult to injury, or the
organisms are on a threshold of surviving. Time of year may be critical as
well. Very little information exists about these types of effects.
If organisms have been lost, it may be necessary to bring them back. It is
simplest to add both food and organisms at the same time, and adding the
greatest diversity of food and organisms at one time would be best. Good
compost provides this, but can be a problem in logistics. Compost tea is
simpler to apply, but has lower complexity of organisms and less food for
the organisms. High N green materials will provide food for bacteria, while
woodier materials provide food for fungi. Application of any material as a
mulch, i.e., on the surface of the soil, will select for fungi, while
mixing into the soil selects for bacteria. There are commercial products
available which improve the growth of the different organisms, although
these must be used with care in soils where testing to determine effect has
not been performed.
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Q&A session between Dr. Elaine Ingham and E-zine Subscribers!
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This is a real exchange and we hope to encourage you to
ask questions and send comments. We're very excited about this
opportunity to open a dialogue that will lead to further
learning by all of us.
If you have something to share, please email Dr. Elaine
Ingham directly at the following address:
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mailto: sfi@unisun.org
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Time permitting she will attempt to address your email
personally and maybe you'll find it posted in a future newsletter!
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Q&A Session #2
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Q#1:
In 1999, I did not have fish, so I buried green plant material and
earthworms under my corn plants. The corn grew well, in spite of the
summer being short and cold, here, near Seattle. But the kernels did not
develop properly, even tho there was a group of 240 corn plants for
pollination. . Next year, 2000, I will water the corn with solutions
containing in total about 15 elements, but not all elements in one
solution.
For example the calcium will flow in irrigation water on one side (west) of
plants, the phosphate on the other (east) side. Naturally, all plants
will have buried worms and green vegetation, and half the plants will
receive no chemical supplements, and the plots will be replicated at least
4 times. I will spray trace element solutions, individually, one element
at a time. Thanks for the email.
Glen
A#1:
Hi Glen -
The sympstoms you describe are indicative of which mineral deficiency you
are dealing with. Typically, failure to set seed is a lack of boron, and
this is a common deficiency in the soil in this part of the world.
Another alternative is a lack of calcium. If the pollinating tubes cannot
develop, you are out of luck in terms of getting the seeds pollinated.
I expect a brief phone call to the extension service near you might result
in a chat with the corn-specialist in the group, and they might be able to
identify a couple more probable mineral nutrients that could have been the
culprits. It would at least limit the number of treatments you would have
to try. Instead of 15 (!) you might be able to narrow things to 5. Seems
much more manageable.
Most of the above situations can be remedied by getting adequate
mycorrhilza colonization on the root system of your plant. Mycorrhizal
fungi have the enzymes to access mineral nutrients that the roots do not
have the enzymes to allow them to access. So, in many instances, just by
getting VAM inoculant on the plants, you get around all the micronutrient
problems. Let the biology do the work for you.
Elaine
Q#2:
What soil test(s) would you recommend regarding symphylans?
Name Withheld
A#2:
Symphylans are little white soil microarthropods that look very similar to
springtails, only they don't "spring". Their antennae are different than
springtails, and while springtails eat fungi, maybe some protozoa and
algae, symphylans will eat roots sometimes.
The easiest way to determine if symphylans are attacking roots would be to
check the roots for signs of symphylan bites. If you have a dissecting
microscope, you can pull roots from plants you think are being attacked,
and from plants you think are free from symphylans. Wash the roots gently,
then using the dissecting scope, look along their surface. Look for bites
taken out of the root. Recent damage looks like craters in the root
surface, half-moons of removed tissue when viewed from the side. Look for
areas with dark black necrotic lesions centered around an initial
semi-circular area where the bite was taken and then fungal or bacterial
disease managed to get established. Compare roots from the damaged area
with roots from areas without damage.
If roots from the damaged area have lots of bites and lesions, while roots
from the good area do not have these symptoms, then symphylans are your
problem. If roots from both places look un-chewed, then symphylans are not
the problem. If roots from both places looked chewed, symphylans are not
the sole cause of the damage - something else is getting in the roots and
causing damage.
You can send roots to SFI and we can assess them if you don't have the
microscopes, or the expertise to assess bites or necrotic lesions.
Alternatively, you can send roots to the OSU Plant Pathology lab, and they
can tell you about the disease organisms infecting the symphylan bites.
Problems with symphylans have always been the result of one or all of the
following things, based on my experience, which is admittedly limited, just
like everyone else I know:
1. Lack of fungi in the soil. We hypothesize that symphylans actually eat
fungi. We have correlative data showing that when fungal biomass was
lowest in the soil, symphylan damage on the roots was highest. Symphylan
feeding on roots was not in any way related to the number of symphylans in
the soil. High symphylan numbers may not result in any root damage. High
numbers can result in a lot of root damage, but you can get the same amount
of damage in an area with low symphylan numbers. We think that when
symphylans run out of fungi and are starting to starve, they'll eat
anything they can get their mouths around. Root hairs aren't much bigger
than hyphae.
2. Lack of surface protection for symphylan predators, lack of predators.
Just as with any microarthropod in soil or on the soil surface, keeping
their numbers down requires a predator. Insecticides, nematodes, and
plowing of any kind kill the predators themselves and often destroys their
homes. These predators are just a bit bigger than symphylans themselves.
The predator here in Oregon is reddish in color, with flattened disk-like
bodies. They remind me of flying saucers with legs and about as silly
looking as they gambole through the soil. How they catch a symphylan is
beyond me, but they are quite effective. Dr. Ralph Berry and some of his
students can comment better than I on these and other symphylan predators.
Predators need protection from birds, centipedes, spiders, etc. A
half-inch or so of hay or mulch on the soil surface is needed to protect
them. They don't like wet areas.
3. If the soil is too wet, bacteria have grow rapidly, and fungi are
out-competed for food, or the soil becomes anaerobic which kills the fungi.
When fungal biomass is reduced below about 100 ug per gram soil,
presumably the symphylans don't have enough fungi to feed on and we see
root damage. The predators head to drier ground and the symphylans can
take a serious toll on the roots. At least that's what we've seen in a few
look-see field studies.
Based on a tiny bit of information, what you want to do is increase fungal
foods (compost is good!), increase predators by giving them habitat, and
don't let things get too wet.
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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! We hope you decide to purchase this
first CD. If you have an interest in helping us distribute this line
of products we'd love to chat with you further... Please read on!
********************************************
DR. ELAINE INGHAM's CURRENT PUBLISHED WORKS
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Compact Disc: Dr. Ingham Talks on the Soil Foodweb
Speaker: Dr. Elaine Ingham
Lable: Coyote Hill MultiMedia
Distributor: Unisun Communications
Format: Double CD Set
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.
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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
For more information, to order, and to even PREVIEW her CDs please
visit http://www.soilfoodweb.com or visit us at http://www.unisun.org/artists/ingham
If you wish more to get information on distribution, wholesale/reseller
pricing, and press opportunities with Dr. Ingham and other Unisun Communications
& Coyote Hill Multi Media Products please let us know and we'll give you
a direct phone call!
Or....
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Peace,
Samuel Anthony Ettaro II
Unisun Communications
http://www.unisun.org
(541)367-8980