In article ,
Chuck Banshee wrote:

On Mon, 16 Jan 2012 21:56:44 -0800, Billy wrote:
Most plants take up nitrogen primarily in the form of nitrate (NO3-)
€¢ except in conditions where nitrifying bacteria don't grow well
(low pH, anaerobic). Then ammonia (NH4+) will be available for uptake

Now that's interesting!

Since it's compost we're working with, we don't know (yet) which plants
will be using the nitrogen.

So, I guess, we want the nitrogen as both a nitrate (NO3-) and as an
ammonia (NH4+).

I wonder how we know if a plant that we plan on fertilizing with this
compost uses its nitrogen as nitrates versus ammonia?

And, depending if we want more nitrates versus more ammonia, I wonder
what we'd need to do to tilt the chemical balance one way or the other?

As the article says, the reaction is driven by the pH; High pH -- NO3-,
Low pH -- NH4+

In general, annuals like high pH, and perennials like low pH.

http://en.wikipedia.org/wiki/Mycorrhiza
Another wrinkle that I haven't investigated much is mycorrhiza. A
symbiotic (generally mutualistic, but occasionally weakly pathogenic)
association between a fungus and the roots of a vascular plant.
----

You really don't need to worry about the NO3-/NH4+ ratios, because
healthy soils will feed your plants.

Teaming with Microbes: A Gardener's Guide to the Soil Food Web
Jeff Lowenfels and Wayne Lewis
http://www.amazon.com/Teaming-Microb...l/dp/088192777
5/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1206815176&sr= 1-1
(Available at a library near you.)

Chapter 1

What Is the Soil Food Web and Why Should Gardeners Care?
Most gardeners think of plants as only taking up nutrients through root
systems and feeding the leaves. Few realize that a great deal of the
energy that results from photosynthesis in the leaves is actually used
by plants to produce chemicals they secrete through their roots. These
secretions are known as exudates. A good analogy is perspiration, a
human's exudate.

Root exudates are in the form of carbohydrates (including sugars) and
proteins. Amazingly, their presence wakes up, attracts, and grows
specific beneficial bacteria and fungi living in the soil that subsist
on these exudates and the cellular material sloughed off as the plant's
root tips grow. All this secretion of exudates and sloughing-off of
cells takes place in the rhizosphere, a zone immediately around the
roots, extending out about a tenth of an inch, or a couple of
millimeters (1 millimeter = 1/25 inch). The rhizosphere, which can look
like a jelly or jam under the electron microscope, contains a constantly
changing mix of soil organisms, including bacteria, fungi, nematodes,
protozoa, and even larger organisms. All this €œlife" competes for the
exudates in the rhizosphere, or its water or mineral content.

At the bottom of the soil food web are bacteria and fungi, which are
attracted to and consume plant root exudates. In turn, they attract and
are eaten by bigger microbes, specifically nematodes and protozoa
(remember the amoebae, paramecia, flagellates, and ciliates you should
have studied in biology?), who eat bacteria and fungi (primarily for
carbon) to fuel their metabolic functions. Anything they don't need is
excreted as wastes, which plant roots are readily able to absorb as
nutrients. How convenient that this production of plant nutrients takes
place right in the rhizosphere, the site of root-nutrient absorption.

At the center of any viable soil food web are plants. Plants control the
food web for their own benefit, an amazing fact that is too little
understood and surely not appreciated by gardeners who are constantly
interfering with Nature's system. Studies indicate that individual
plants can control the numbers and the different kinds of fungi and
bacteria attracted to the rhizosphere by the exudates they produce.
During different times of the growing season, populations of rhizosphere
bacteria and fungi wax and wane, depending on the nutrient needs of the
plant and the exudates it produces.

Soil bacteria and fungi are like small bags of fertilizer, retaining in
their bodies nitrogen and other nutrients they gain from root exudates
and other organic matter (such as those sloughed-off root-tip cells).
Carrying on the analogy, soil protozoa and nematodes act as €œfertilizer
spreaders" by releasing , the nutrients locked up in the bacteria and
fungi €œfertilizer bags." The nematodes and protozoa in the soil come
along and eat the bacteria and fungi in the, rhizosphere. They digest
what they need to survive and excrete excess carbon and other nutrients
as waste.

Left to their own devices, then, plants produce exudates that attract
fungi and bacteria (and, ultimately, nematodes and protozoa); their
survival depends on the interplay between these microbes. It is a
completely natural system, the very same one that has fueled plants
since they evolved. Soil life provides the nutrients needed for plant
life, and plants initiate and fuel the cycle
by producing exudates.

Soil life creates soil structure

The protozoa and nematodes that feasted on the fungi and bacteria
attracted by plant exudates are in turn eaten by arthropods (animals
with segmented bodies, jointed appendages, and a hard outer covering
called an exoskeleton). Insects, spiders, even shrimp and lobsters are
arthropods. Soil arthropods eat each other and themselves are the food
of snakes, birds, moles, and other animals. Simply put, the soil is one
big fast-food restaurant. In the course of all this eating, members of a
soil food web move about in search of prey or protection, and while they
do, they have an impact on the soil.

Bacteria are so small they need to stick to things, or they will wash
away; to attach themselves, they produce a slime, the secondary result
of which is that individual soil particles are bound together (if the
concept is hard to grasp, think of the plaque produced overnight in your
mouth, which enables mouth bacteria to stick to your teeth). Fungal
hyphae, too, travel through soil particles, sticking to them and binding
them together, thread-like, into aggregates.

Worms, together with insect larvae and moles and other burrowing
animals, move through the soil in search of food and protection,
creating path-ways that allow air and water to enter and leave the soil.
Even microscopic fungi can help in this regard (see chapter 4). The soil
food web, then, in addition to providing nutrients to roots in the
rhizosphere, also helps create soil structu the activities of its
members bind soil particles together even as they provide for the
passage of air and water through the soil.

Soil life produces soil nutrients

When any member of a soil food web dies, it becomes fodder for other
members of the community. The nutrients in these bodies are passed on to
other members of the community. A larger predator may eat them alive, or
they may be decayed after they die. One way or the other, fungi and
bacteria get involved, be it decaying the organism directly or working
on the dung of the successful
eater. It makes no difference. Nutrients are preserved and eventually
are retained in the bodies of even the smallest fungi and bacteria. When
these are in the rhizosphere, they release nutrients in plant-available
form when they, in turn, are consumed or die.

Without this system, most important nutrients would drain from soil.
Instead, they are retained in the bodies of soil life. Here is the
gardener's truth: when you apply a chemical fertilizer, a tiny bit hits
the rhizosphere, where it is absorbed, but most of it continues to drain
through soil until it hits the water table. Not so with the nutrients
locked up inside soil organisms, a state known as immobilization; these
nutrients are eventually released as wastes, or mineralized. And when
the plants themselves die and are allowed to decay, the nutrients they
retained are again immobilized in the fungi and bacteria that consume
them.

The nutrient supply in the soil is influenced by soil life in other
ways. For example, worms pull organic matter into the soil, where it is
shredded by beetles and the larvae of other insects, opening it up for
fungal and bacterial decay. This worm activity provides yet more
nutrients for the soil community.
---

No man, or plant is an island.
--

Billy

E Pluribus Unum

Every gun that is made, every warship launched, every rocket fired signifies in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed. This world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children. This is not a way of life at all in any true sense. Under the clouds of war, it is humanity hanging on a cross of iron.
- Dwight D. Eisenhower, 16 April 1953