Compost is organic matter in which certain sets of organisms have
grown, using the organic matter present, and in the process of growing, have
released metabolic heat. That heat kills weed seeds and kills, or reduces as
far as reasonably possible, human and plant disease-causing organisms. But
good compost should not be allowed to reach too high a temperature, or the
carbon-containing compounds will begin to burn, producing a smell like
charcoal, and with similar compounds that can kill or inhibit plant growth.
Good compost is "mature," which means both that temperature has reached
ambient levels, that the N-immobilization phase has been completed, and
nutrient cycling is occurring.
Compost can be guaranteed to contain huge numbers of organisms, and compost
managed properly will contain huge numbers of organisms beneficial to the
growth of plants.
Good compost contains an enormous number of organisms, much greater than
are typically present in soil. There are organisms in compost that are unique
to compost, and will not survive when mixed into soil, or if the compost is
applied as a mulch on the soil surface, will die as the compost becomes
incorporated into soil. This is perfectly normal, and actually must occur to
build soil.
But that's why compost is used: To improve the foodweb in the soil, and to
provide food for soil organisms to continue to do their jobs. The same
benefits can be obtained by just adding
organic matter, but there is a possibility of problems when the organic matter
is not properly managed before adding it to the plant-growth system.
Good compost also contains an enormous number of food resources for the
organisms growing in it. All those organisms need food to stay alive so they
can help your plants grow. If
soil organisms could talk, they'd tell you, "No food, no work." Just like
teen-agers, soil organisms won't do what you want them to do if you don't feed
them.
But in order to maintain the diversity of organisms in the soil, a wide
range of food types are needed. Imagine a city without many, many types of
foods available. If the only thing you had to eat were French-Fries, you'd go
looking for a better place to live quite soon. Soil organisms are not
different. They need a diversity of food resources in order to maintain all
the species that should be there, their "ethnic" diversity. Therefore, a wide
diversity of food types is needed, and the more the better.
Why is diversity important? Think about all the diseases that can attack
your plants. Ten, twenty, or a hundred different
diseases? It depends on the plant, the soil type, and where you live. But
consider, for example,work done by Dr. W. Mahaffee at Oregon State University
(published in the American Journal of Phytopathlogy). From his work a bit, one
could extrapolate that for each foliar disease-causing organism, there are
probably at least 12 to 15 different species of bio-control organisms that
need to be present through a single summer in order to prevent that disease.
And that's just one cultivar of plant, just one summer. Consider that the
same thing has to be occurring for each pathogen, for each part of the plant,
for each set of environmental conditions. Work being done by plant
pathologists all over the world is demonstrating that each cultivar of plant
has its own particular "best-disease-preventing" bacteria, or fungi. Consider
that there can be several races of each disease. Each one requires it's own
particular set of bio-control organisms. And each summer with different
environmental conditions requires a different set of bio-control organisms to
be present.
Some researchers estimate the number of species of bacteria in agricultural
soil at 10,000 to 15,000 per teaspoon. How many individuals of each species?
We know that there should be at least a 100 to 1000 million individuals
total of all species in a healthy soil, but we're not certain how many
individuals of each species is required to prevent disease.
Do we throw up our hands and give up because there's so much to know? No,
we just maximize the diversity of these species of beneficial bacteria and
fungi in the soil. We provide as complex
a set of food resources as we possibly can. We provide as complex a set of
places to live in the soil as we possibly can. Let's have every bacterial
species, or fungal species we could possibly
need present and ready to work. Then we don't have to worry about whether we
have the single "right species."
Good compost contains as diverse a set of organisms, as diverse set of food
resources, and as good aggregate structure as possible. Diversity will be
maximized and will transfer that complexity of species and functional groups
into the soil on which, or into which, the compost is placed.
Good compost supplies the following things:
1.A huge diversity of different kinds of organisms (what kinds - see below).
2.An enormous number of species of each different kind of organism (how many -
see below).
3.A broad range of different types of food to keep all these species and
individuals alive (what kinds of food - see below) and,
4.The ability to form good aggregate structure so the spaces that different
organisms need are built.
Compost ultimately improves plant health by supplying these things to the
soil. That's why adding compost helps keep plants healthy.
The Benefits of Using Compost Just as with soil, compost benefits plant
growth by providing:
1.The set of organisms - the compost foodweb - that cycles nutrients into the
right forms at the right rates to maintain
composting processes and, if inoculated into soil, will supply nutrients for
healthy plant growth.
2.An inoculum of organisms that can suppress disease-causing organisms.
3.The set of organisms that build structure, so mineral nutrients and gases
(oxygen) can move through the compost easily, so a
greater amount of water can be held in the compost. When added to soil, these
organisms provide an inoculum of organisms that will build soil structure,
with all the attendant benefits.
4.The set of organisms that degrade toxic materials, plus the food for
organisms to maximize co-metabolic processes, allowing
the maximal rates of highly toxic compounds to be processed. Care must be
taken that complete metabolism will occur.
5.The set of organisms that make plant-growth-promoting hormones and
chemicals.
6.For appropriate soil chemistry for the plant. The pH of any material is only
a very general indicator of correct conditions for a plant. The right amount
of calcium, iron, phosphorus, sulfur, and so forth must be presented to the
plant in the right amounts at the right times. If all the Ca is complexed in
forms the plant can't use, the plant will suffer, and succumb to disease
because it is too stressed to resist the disease. Salt is an important factor
- not too much and not too little. The Goldilocks Principle - just right!
Matching Compost to the Plant to be Grown The organisms in compost should
match the needs of the plant. If the compost is to be placed on trees, the
microorganisms in that compost should be those microbes that help trees, and
in this case, the compost should have more fungi than bacteria. If the compost
is going on
vegetables, a set of organisms typically should have more bacteria than fungi.
Vegetables, turf, lawns, and row crops do best in bacterial-dominated
soils. There are several reasons:
1.Bacteria produce "slime layers" around their bodies, which they use to glue
themselves to surfaces. This prevents them being washed out of the soil, so
they retain nutrients in the soil. But this slime layer is most often made of
alkaline materials, which may cause soil to become more alkaline.
2.Bacteria are eaten by protozoa and bacterial-feeding nematodes, releasing
ammonium into the soil.
3.In alkaline conditions, maintained by the slime layers and secondary
metabolites that bacteria produce, nitrifying bacteria thrive and convert
ammonium to nitrate quite rapidly. Nitrate is the preferred form of N for most
row crops, grasses and vegetable
crops. Thus, these plants grow best in bacterial-dominated soils.
Trees, shrubs and many perennial plants do best in fungal dominated soil,
for the following reasons:
1.Fungi make organic acids as their waste products.
2.Fungi are eaten by fungal-feeding nematodes, a few species of large amoebae,
and fungal-feeding microarthropods. Fungal-predators release N in the form of
ammonium.
3.Because fungi maintain soil pH on the acidic size, and indeed, beneficial
fungi appear to buffer soil pH between a pH of 5.5 and 6.5, nitrifying
bacteria are excluded from the foodweb. While there are a few species of
nitrifying fungi which are found in unique places (the oak savannas of
California, for example), the majority of N in fungal dominated soils are
present as ammonium, not nitrate. Trees, shrubs and many perennial plants, as
demonstrated by J. Stark and also by Marschener, grow more
efficiently when using ammonium, instead of nitrate.
The "pool" of inorganic N in healthy forests is dominated by ammonium,
while the inorganic N pool in grasslands is dominated by nitrate. Thus for the
best growth of different plants, there needs to be recognition that the
organisms in the soil will set conditions that select for maximum or optimal
plant growth. This is not to say that plants can't grow in sub-optimal
conditions, but it does suggest that plant growth will be stressed in these
conditions, and that disease will be a greater factor in stressed plants.
Check this site for the optimal microbial dominance for your plant. Realize
that the relationships we've discovered are based on observation for the most
part, not on extensive experimentation. For example, we've
observed that most broccoli grows in soil strongly dominated by bacterial
biomass. Experimentation would allow us to determine the best ratio for
each cultivar of broccoli, in each climate, in each soil type. Does
cultivar A do best with a fungal-to-bacterial biomass ratio of 0.30 (three
times more bacteria than fungi), or with a ratio of 0.25 (four times more
bacteria than fungi)? We don't know this level of information yet for the most
part.
Something else we have little data on, but seems to hold true, is that the
optimal ratio of fungi to bacteria changes as the soil type changes. Broccoli
may need 0.4 ratio in low organic matter sand, but 0.2 in loamy sand. Lots to
learn about here!
Good compost also needs various micronutrients. The Goldilocks principle
applies, not too much or too little, neither too high nor too low, not too
hard and not too soft. Good compost, by
definition, has a wide diversity of organisms that compete with, inhibit and
consume disease causing and pest organisms. It has food for all the beneficial
organisms, but is not high or low
in nitrate or salts (conductivity).
Compost and Aggregate Structure Aggregates develop through a rather
complex biological process. As a result of soil organism
actions, soil or compost develop structure which allows oxygen and water to
easily move through the material. Bacteria make the smallest microaggregates,
as they glue clay colloids, soil organic matter, silt and sands together. They
make "condominium housing" for themselves and other small organisms in soil.
Fungi grow as long threads, which bind the microaggregates together into
macroaggregates.
The physical placement of macroaggregates is engineered by microarthropods,
nematodes, insect larvae, and earthworms. All these things working together
result in good soil pore structure. This means there is plenty of space for
water to infiltrate into the soil, for oxygen to diffuse to the root system,
and to allow carbon dioxide to move out of the soil. Without good soil
structure, soil becomes anaerobic. Water puddles on the soil surface, and
erosion can become a problem.
In addition, if compost or soil isn't well-aggregated, there will be few
places for the bacteria to hide. The predators will eat more bacteria than
will allow a good balance. Nutrient retention will not occur, too much
ammonium will be released, and not enough nitrate will be converted to nitrate
by nitrifying bacteria. Row crops, grass or vegetables may look as if they
need fertilizer, but what is really needed is to improve soil structure so the
bacteria have places to escape their predators.
Without bacteria and fungi in the soil most of the fertilizer you add will
wash through the soil into ground water and into drinking water. One way to
look at this is that you're spending money on fertilizer so you can spend even
more money cleaning up your drinking water. We need to get back the organisms
that will hold nutrients in the soil.
Does it mean fertilizer is a thing of the past? No, because nutrients are
removed when we harvest. But we need to stop nutrients moving through the soil
into the groundwater. The only way to stop that loss is to get the organisms
back in the soil, get them to hold on to the nutrients. If nutrients are HELD
in the soil, by the bacteria and fungi, then those nutrients will become
available to plants in the future. Less fertilizer will be needed. Less money
will be required to clean up our drinking water.
A healthy number of bacteria, a healthy number of bacterial species, a
healthy amount of fungal biomass, and fungal species to build the "walls" of
the soil condominium. Then protozoa, nematodes, and microarthropods are needed
to engineer the "walls" in the right places. It would be great to know exactly
what bacterial species, what fungal species, protozoan, nematode and
microarthropod species make the soil most appropriate for any specific plant,
but we aren't at that point of understanding yet. The best we can do now is to
try to maximize bacterial diversity and hope the best bacteria are present,
and that the plant itself will help select the desired bacterial species.
The Composting Cycle How do you control the set of organisms, supply high
food diversity, and balance chemistry? Basically, how do you make good
compost? Here are some of the basics of the process, and some of the factors
that should be considered:
1.The starting materials select for the final mix of organisms and the
temperature that will be reached. Thus, the recipe used to start the pile
needs to be altered depending on what final product is desired.
2.Monitor temperature. The temperature must reach 135 F, for at least 3 days
in the whole pile. Add nitrogen and/or bacteria if the pile is too cool. Add
high carbon-containing material (remove N), add cold water, or turn the pile
if the pile is too hot. In places were there are especially heat-tolerant
seeds, 160 F may be a good idea however. Check with Extension specialists, a
plant ecologist or botanist if you have questions about temperatures needed to
kill seeds of different plants.
3.Monitor the smell of the compost pile, or if you have an oxygen probe, use
it to determine oxygen concentration in the pile. But your nose is a pretty
sensitive measurement tool. If the compost smells burned, or the compost
becomes black (black, not dark brown), the temperature is too hot and the
compost is turning into charcoal which will result in phytotoxicity). If the
pile emits bad odors, like a swamp or an outhouse, or smells like rotten eggs,
vinegar, sour milk, or vomit, the pile has anaerobic
conditions in it and needs more oxygen. Turn, or add more bulky materials so
oxygen can diffuse more rapidly. Reduce bacterial growth, so oxygen is not
used up.
A range of particle sizes in the starting materials is needed. If all the
particles are small, air has a hard time diffusing through the pile. Small
particle size means there are many surfaces for the bacteria grow on and they
will use up all the oxygen. If all the particles are large, bacteria won't
have many surfaces to attack, and the pile may never heat enough.
4.As temperature begins to come down, because the bacteria run out of food
resources, the pile goes through "maturation." Populations of protozoa and
beneficial nematodes have to grow up during this time and begin the process of
cycling nutrients.
5.Mature compost occurs when most of the easily usable food resources have
been used. This means that when the compost pile is turned, there is no
significant heating that occurs. The activity of the bacteria and fungi remain
below 10%.
Starting Materials
Much of the composting cycle can be controlled by the
recipe used to start the pile. There are
five important factors to consider in choosing the starting materials for the
pile:
1.N content/the kind of C. Nitrogen, abbreviated N, and carbon, abbreviated C,
determine the quality of the food resources in the starting materials. The
easier the N is for the bacteria to use, the faster the bacteria will grow,
the more rapidly the
temperature will increase, and the hotter the pile will get. The less easy the
N is to use, the slower the bacterial growth, the lower the temperature, and
the cooler the pile. The balance of easy-to-use N (bacterial growth) to
hard-to-use C (fungal growth) will determine a great deal of the composting
process. The kinds of plant materials that are easy-to-use N and hard-to-use C
are explained below.
2.Particle size of the starting materials. The smaller the size of the
particles, the easier the food is for bacteria to use. If particle size allows
too rapid bacterial growth, temperature will increase too quickly, become too
high, and the oxygen will be used up, resulting in anaerobic conditions.
3.Turning cools the pile immediately, but may result in a concomitant
bacterial "bloom," with effects on temperature and oxygen use rates.
4.Moisture must be adequate to let the organisms grow, but as water content
increases above 25%, oxygen diffusion is reduced and may lead to anaerobic
conditions.
5.Easy-to-use C and N materials will select for bacterial growth, while
hard-to-use C and N will select for fungal growth. Probably the most generally
useful compost would have balanced bacterial and fungal biomass, since then
the plant would select for dominance of the microorganisms most beneficial to
it. However, as broad a diversity of both bacteria and fungi would be most
beneficial, regardless of what system into which the compost will be placed.
The Basic Bacterial Starting Recipe For bacterial compost, start with:
25% hi N material, such as alfalfa or manure (see below about different
kinds), 50% green leafy material (avoid material to which pesticides were
applied), and 25% woody, brown, dry leaf, straw, hay, bark materials.
Manure. If the manure is stinky, wet, or runny, reduce the amount of manure
used. It is quite likely that this manure will be high in salts and will
result in phytotoxicity. Use only 10% manure and increase the percent green
and woody materials.
The Basic Fungal Starting Recipe For fungal compost, start with: 5-10%
hi N material, such as alfalfa or manure (see below about different kinds),
45-50% green leafy material (avoid material to which pesticides were applied),
and 40 - 50% woody, brown, dry leaf, straw, hay, bark materials. These recipes
are just starting points. We need to collect a greatdeal more data on the
outcome of use of these recipes. We know, for example, that limbs pruned in
the springtime and chipped into a pile results in more bacterial growth and
faster heating than the same volume of woody material in the fall. Why?
There's more plant sap (i.e., sugar and N-rich proteins) in pruning material
in the spring than in the fall. You have to think about the quality of the
material added to the pile.
Trial-and-error are important to improve the compost beyond the basic
recipes given above. If your compost heated too fast, you have too much juicy,
N-rich green stuff. Reduce its volume in the next batch by perhaps 10%. If
pile #2 didn't heat enough, increase the amount of juicy, N-rich stuff by 5%.
Too hot again? Add more straw. Keep adjusting until you can make a pile that
needs littleturning, but gets to temperature and stays there for 15 days, then
comes down to ambient, and gives no further heating even when turned.
There are seasonal differences in materials available to start piles.
What's the difference between apple cores and pear cores? They contain
different sugars, different tannins, different proteins, and different
minerals. Are the differences enough to affect the composting process? Not
that anyone has ever mentioned. What foods are exchangeable without any
effect, and which ones change the compost? We need to work on this.
Development of a database would be a good idea.
Particle Size The size of the chips and chunks in your pile make a
difference. Chunky material lets more air diffuse in more rapidly, cools the
pile down, and keeps temperature lower without having to turn. Finely chopped
material reduces the size of openings in the pile, prevents oxygen from
diffusing quickly, and prevents cooling. Too finely chopped material means the
pile gets very hot, very anaerobic, very fast. To prevent anaerobic
conditions, turning may have to be done every 15 minutes data presented on
"Magic Soil" web site). But there's a trade-off. If the compost is made with
bigger chunks, there will be less need to turn to maintain oxygen levels, but
the final product may need to be screened. These chunks are great microbial
"starters" for the next pile, however.
Why Are Anaerobic Conditions Bad? Why are anaerobic conditions so bad?
When anaerobic metabolites are produced, volatile organic acids (valeric acid,
butyric acid, phenols, see Brinton, 1997), phenols and terpenes are produced.
These compounds are very detrimental to the growth of plants and beneficial
bacteria, fungi, protozoa and nematodes.
Compost that contains anaerobic metabolites kills, or at the very least
reduces the growth of plants in containers into which the compost has been
placed. Between salt and anaerobic metabolites, probably 75% of the
phytotoxicity problems with poor "composts" are explained. The remaining 25%
of the problems producing phytotoxicity relate to lack of predators in compost
to make nutrients available for plant growth.
There are three general classes of bacteria with respect to oxygen
concentration. There are: 1) Strict aerobes, 2) Facultative anaerobes and 3)
Strict anaerobes. Strict aerobes require oxygen concentrations around normal
atmospheric levels (15 to 22% oxygen concentration) in order to perform the
functions of life. Examples of some of these genera of bacteria are
Pseudomonas, Bacillus, and Aerobactor.
Facultative anaerobes switch from aerobic to anaerobic metabolism when
oxygen becomes limiting (around 8 to 9% oxygen). Examples of bacteria that are
facultative anaerobes are E.coli, Klebsiella, and Acinetobactor. Strict
anaerobes require low oxygen concentrations (less than 2% oxygen for example)
to
grow. An example of a strict anaerobic bacterium is Clostridium.
Aerobes, facultative anaerobes and strict anaerobes are everywhere. They
live in soil, on plant surfaces, on the surfaces of stones, on and in
pavement, and clothes. Facultative anaerobes
include some species that are highly beneficial to plants as well as some
disease-causing species. These organisms are needed so that the cycling
processes within nature can occur. Thus, sterilization is NOT the answer. The
point is to maintain aerobic conditions, so the benefits from a widely diverse
What conditions result in the switch to anaerobic metabolism? Anaerobic
metabolism can be triggered whenever oxygen diffusion into the compost is
restricted and/or rapid bacterial growth occurs. Some people are surprised to
think that bread rising on the counter develops anaerobic conditions. The
yeast grows so rapidly that oxygen is used up, but objectionable odors are not
produced. Even the sandiest soils have anaerobic zones in the middle of the
aggregates. Roots must have anaerobic zones if they contain nitrogen-fixing
bacteria, since N can only be fixed under oxygen-limited conditions.
Rapid bacterial growth maintains anaerobic conditions. In compost,
extensive anaerobic conditions are not desirable, because of the effect
alcohols, phenols and terpenes have on plant growth. Thus, oxygen needs to be
able to diffuse into the pile. Size of particles, turning frequency and
keeping bacterial growth at reasonable rates by controlling the kind of food
resources present are the keys to keeping compost from stinking.
The Temperature Cycle
The starting materials used control
temperature and therefore the time between turning events. The greater the
amount of "juicy," easy-to-use, N-rich material, the faster the bacteria grow.
The faster the bacteria grow, the more rapidly temperature increases, and the
higher the peak temperature reached. In addition, the faster the bacteria
grow, the more likely that diffusion of air into the pile will not be fast
enough to balance oxygen used by the bacteria.
Temperature starts at ambient levels, whatever that may be given the time
of year. Typically, using the recipes above, temperature climbs to above 135 F
in 24 to 72 hours. If temperature has not reached that level in that time,
something is killing the bacterial biomass. The most likely culprits are
pesticides used on the green material, woody material that was too fresh
(fresh bark can contain high quantities phenols and tannins that are
detrimental to bacteria and fungi), high salt-containing manure, or
antibiotics used in the animal feed. The solution is to inoculate with more
bacteria, and add more juicy green stuff to get bacterial activity going.
Temperature should be monitored and remain above 135 F throughout the core
of the pile (from 1 foot into the pile through to the center), with only a
short period of reduced temperature each time immediately after the pile is
turned, for 10 to 15 days. Add green juicy stuff, or sugar,if temperature
begins to drop below that level, and alter the initial recipe to include more
green material.
Temperature should not go above 150 to 155 F. The higher the temperature,
the more the species of bacteria and fungi are changing, and once temperature
goes over 15, the species of mid-temperature bacteria either go to sleep, or
die. The true heat-loving bacteria continue the process of growing, and
heating the pile, until the food resources run out. Then temperature will
begin to drop. But, as temperature drops, the heat-loving bacteria go to
sleep, but the mid-range temperature bacteria may not wake up. Just as if they
don't trust you for letting the pile get so hot, they seem to be cautious
about waking up. So there may be a period of time when there's basically
no-one-at-work in the pile. The heat-lovers got too cold, and headed for bed,
while the next set of guards haven't woken up to come on-duty yet. It is under
these conditions that I have seen Aspergillus, or Fusarium take over the
compost pile. This situation can truly be life threatening, because these
fungi produce enormous numbers of spores. If you turn the pile and breathe in
these spores, they can cause a lung-infection that is very difficult to treat.
Just as an additional note, if you see organic material (grass clippings for
example) covered with powdery white stuff, do your lungs a favor and wet the
pile down before you turn it.
Alternatively, cover the pile with more leaf or compost material and mix the
pile before turning it. Don't let the spores fly, don't breathe them in. If
composting is done correctly, have these problems don't occur, however.
Turning
Cost must be considered with turning. The more times compost is
turned, the more expensive the compost - either in terms of back pain or gas
money and equipment wear and tear. But the more compost is turned, the less
the time to maturation. With a backyard compost operation, compost is started
in the late summer usually, and isn't needed before spring, so turning is
probably not necessary, as long as a few chunks can be tolerated.
But in a commercial operation, where turn-around is important with respect
to production of profit, making good compost in four
weeks is necessary. Also, most compost operations don't have unlimited space
to make compost, so static piles, taking a year or more to mature, take too
much space. In these cases, less juicy N-rich material is indicated, because
it is making your bacteria grow too fast, raising temperature beyond required
levels, using up air, and making it necessary to turn more often. Put the
bacteria on a sensible diet.
Enough juicy N-rich green stuff balanced with enough woody, straw, brown
leaf material to get to temperature to 135 F in 24 to 72 hours, but no more
than 155 F over a week period of time. Then, just as oxygen becomes limiting,
turn the pile.
What's the magical recipe to achieve this? Trial and error, until we learn
more about exactly which bacteria and fungi are encouraged by what kinds of
combinations of high N manure plus hi N green plus green plus woody
combinations.
To prevent stinky, smelly compost that make neighbors into enemies, and
bring the municipal authorities out to investigate, turn the pile when oxygen
begins to fall below 12%-15%. Or insert pipes into the pile that allow air to
diffuse in, or be pumped through.
In order to prevent the pile from bursting into flame, the pile has to stay
below 175 to 180 F. Cooling can be achieved by turning, applying cold water,
or adding woody materials (straw, sawdust, newspaper, dead leaves) to balance
the juicy, N-rich food resources. Turning can be problematical, if the juicy,
N-rich materials weren't balanced with woody stuff at the beginning of the
cycle. Turning can reduce temperature for a short time period, but then,
because turning opened up more surfaces for the bacteria to start growing on,
an even higher temperature can result as bacteria take off again on the new
food resources.
Maturation
As the compost cools, protozoa, beneficial nematodes and
microarthropods come out of the dormant stages they entered when temperature
started to increase. They will consume the huge numbers of bacteria and fungi
present and get nutrient cycling going again, making nutrients available for
plant growth.
Another major reason for plant phytotoxicity in poor composts is that the
protozoa, beneficial nematodes and microarthropods were killed during in the
composting cycle. Several things could kill them:
1.Pesticides in some of the starting materials.
2.Rapid bacterial growth. If the temperature increased very rapidly, the
predators could be killed before they could enter dormant conditions.
3.Anaerobic conditions will kill the predators.
4.Lack of diversity in starting materials, such that a toxic bacterial or
fungal species dominates the pile.
5.Too high temperature which killed the predators throughout the pile.
When no or few predators remain in the compost, bacteria and fungi tie-up
all the nutrients, and the nutrients remain in the bacteria and fungi. Plants
will be out-of-luck for nutrients, and
will be extremely stressed and easily succumb to disease.
Static Piles
Most of the above discussion has assumed a desire to make
compost as rapidly as possible, to minimize the turn-around time. But, there
may be reasons to use a static pile. In this method, large branches or chunky
material is placed on the ground to start. A layer of usually fungal-recipe
material is then placed over the big pieces. This bottom layer acts as an air
intake area.
High-N containing materials are then added on top, in the middle of the
bottom layer. These materials can be whole animal carcasses, or human biosolid
material. Several hundred dead
chicken carcasses have been composted in this fashion - without smell escaping
from the pile. The high-N material is then covered with the normal compost
material, and the composting cycle starts.
Extremely high temperatures have been reported in the middle of these
piles, but they are highly anaerobic, and so do not burn. Care must be taken
not to open these piles too soon (they may spontaneously combust).
Additionally, if any smell is detected from the decomposing high-N material,
and additional foot depth of compost material should be added to the outside
of the pile.
After six to nine months (depending on the amount of high N material in the
pile), gently dig into the pile. If temperature is still high, or stink is
detected, close your divot up, and wait another three to six months before
checking again. Eventually, the anaerobic products will be used up so that
when the pile is opened, neither smell nor carcass material will be found.
Even the bones may not be detectable. The pile should be turned a few times to
make sure all temperature spikes are finished.
Static piles take a great deal of time and space. But they can be the most
effective ways to deal with truly obnoxious material.
Mature Compost
Mature compost does not heat significantly when turned
(maybe a few degrees, but that's it). Mature compost contains organisms that
are less than 10% active. The blooms of growth have occurred, and the
predators have returned to consume bacteria and fungi to consistent, typical
levels. Mature compost does not have conditions that would cause
phytotoxicity, or in other words, seedlings of plants could be grown in
straight compost (100% compost, no amendments). Immature, or improperly
composted material, will cause phytotoxicity, where seedlings will not survive
in unamended compost.
Since we focus on what organisms should be present, at Soil foodweb Inc.,
we tend to define good compost by the organisms that should be present, and
are given below for a typical 1:1 ratio of fungi to bacteria compost. < p>
Bacteria
Good compost will have on the order of a 1,000 million
bacteria per teaspoon (109 bacteria per teaspoon). Most of these individuals
are beneficial to plant growth, and do not cause disease.
Fungi
There should be 150 to 300 meters of fungal biomass per teaspoon of
compost. Fungi produce humic acids, and thus a significant humic acid
component should be present. If an extract of the compost is made, a rich dark
brown color should occur. If the color is light or tan in color, few humic
acids have been produced, only fulvic acids, indicating mostly bacterial
activity.
Protozoa
Protozoa go through boom and bust growth cycles in compost,
depending on the temperature and on the presence of their bacterial prey. As
the compost heats, the protozoa encyst to escape the high temperature. When
the compost cools, the protozoa excyst and become active again. As compost
moves into the maturation phase, protozoa may reach 100,000 to 1,000,000 per
teaspoon. Mature compost should only contain 10,000 to 50,000 protozoa.
Flagellates and amoebae do not tolerate anaerobic conditions and will be
killed by lack of oxygen. If the compost becomes anaerobic at any time,
flagellates and amoebae will be lost. They are good indicators of this aspect
of good compost.
Nematodes
Like protozoa, nematodes don't like heat or anaerobic
conditions. Many of the beneficials and all of the root-feeding nematodes will
be killed by the heating process. But a reasonable number of the beneficial
nematodes should survive the heating process to wake-up when the temperature
drops below 135 F. The beneficials then begin to grow, and given the presence
of huge numbers of bacteria and fungi, reach high numbers in a few weeks. It
is important, however, to know the time-since-135 F, since if temperature
drops rapidly, only a few beneficial nematodes could be expected, as their
life-cycles are a minimum two-weeks in duration.
Good compost will contain 30 to a hundred beneficial (bacterial-feeding,
fungal-feeding and predatory) nematodes per gram of material. Really great
compost may contain several hundred beneficial nematodes per teaspoon.
There should be no detectable root-feeding nematodes present in good
compost. If they are found, it indicates that parts of the compost did not
remain above 135 F for the entire composting cycle time. In general, roots
feeders appear to be more sensitive to temperature than beneficial nematodes,
especially when they are not protected by the presence of live roots. If any
root-feeding nematode eggs survive the heat cycle and hatch during compost
maturation, they should be consumed by predatory nematodes, but
nematode-trapping fungi, by microarthropods, and fungal nematode parasites. If
perchance they are not, the lack of live roots in the compost should cause
them to succumb.
Species of bacteria, fungi, protozoa, nematodes The species composition
of bacteria, fungi, protozoa and nematodes in compost depends on the diversity
of food resources. If few kinds of foods were added in the original set of
starting materials, the food resources in the final compost will be minimal.
If there are few bacterial or fungal species, nematodes that require those
missing species to survive will die, or will never have been present to begin.
Healthy compost has been hypothesized to have between 10,000 to 20,000 species
of bacteria per gram, but the DNA analysis required to establish the set of
species in a highly diverse compost versus the number of species in a
not-highly diverse compost awaits an enterprising molecular microbiologist.
One of the areas SFI is currently exploring is how to determine whether the
sets of beneficial bacteria or fungi are present in soil or compost.
Hopefully, in 1999, we will begin to test this system of species
identification and establish a database on how to achieve this set of
beneficial organisms in soil and compost.
Most pathogens cannot compete well with beneficial species. Therefore, by
maximizing bacterial, fungal, protozoan, nematode and microarthropod species
diversity, selection will be against the growth of pathogenic and pest
species.
Mycorrhizal fungi
Mycorrhizal fungi do not grow in compost. The heating
process kills most of the spores, and those remaining are not usually viable.
It is usually of some benefit to add an inoculum of mycorrhizal spores to
compost. The food resources present in compost may cause mycorrhizal spores to
germinate after a few days (72 hours for example). If the germinated spores do
not find active roots within 24 to 48 hours of germination, they die.
Therefore, spores should be added to compost just before planting.
CHATHAM COUNTY & REGIONAL FARMERS
DIRECTORY
In an attempt to better serve the needs of our community, we would like
to introduce to you an opportunity to become listed in a farmers directory.
This directory would be primarily used by consumers trying to locate sources
of fresh vegetables, fruit, herbs, nuts, grains, mushrooms, dairy, meat,
animal products honey, poultry, eggs, crafts, and value added products. This
directory could also be used by businesses, such as the wholesale markets,
trying to locate North Carolina grown farm items.
The Directory would be created for the internet located in the Chatham Co
Extension Web Page. In this manner, your farming enterprise will get exposure
on a broad front. The internet version could be accessed from literally
anywhere. Think of the possibilities.
Please complete the attached form and return to:
Robert Hadad
Chatham County Cooperative Extension
PO Box 279
Pittsboro, NC 27312
For more information call 919-542-8202 ext 244.
CHATHAM COUNTY & REGIONAL FARMERS DIRECTORY
name:
address: street
city
state zip
phone (day)
(evening)
e-mail
farm business hours
(__)check if you want address listed in directory.
(__)check if you want customers to call before coming out to farm.
(__)check if you only want phone # (and e-mail if appropriate).
Please sign in agreement that you want Chatham County Cooperative Extension to
list you publicly. (Note that Chatham County Cooperative Extension is not
liable for anything further except listing this directory as a public service
and as an advertising aid for local growers.)
X
date
List produce and/or products you raise. Include comments about each as
necessary. List time available or expected availability.
List if produce or products are organic, or transitional. Check off if items
would be available in large quantities for wholesale possibilities.
Do you sell through: (__)on-farm sales, (__)farmers markets, (__) CSA
subscription, (__) grocery-type markets, (__) wholesale (___)other
List anticipated items to be produced this season.
Item When available: wholesale possibility(__) Organic (__)
Comments:
.
FARMERS MARKET LISTING
One of the things I going to try to initiate, using the Chatham Co. Web
page is to have a section on the local farmers markets. Each person
participating could have a section in the listing describing what they are
bringing to the market either weekly, twice a month, or monthly. I could have
a simple form you could fill out and get it back to me prior to the week you
would be bringing in those crops or products. You don't have to list prices
but having a good description of the item would help. Here at the Extension
office, we get numerous calls from people asking what is being offered at the
markets. Since so many househods are "turning to the internet", this might be
a way for you all to get a bit more exposure for your sales. If interested,
let me know and I will give you copies of the form.
FARMING 2000 & BEYOND Workshop Series
The FARMING 2000 & BEYOND (fast being refered to as "that Third Wednesday
Night Gathering) Feb. workshop on Value-Added Production, Marketing, and
Regulations was very well attended. This was the second in the series and the
first to be held in Chatham Co. Participants gathered a lot of very useful
information that will hopefully be used to increase profitability on their
farms.
The workshops also serves the function as being the catalyst for farms to
get together and meet others like themselves. A great deal of networking took
place between and among attendees. This is really important too because there
is alot to be learned from each other, not just from specialists. I even made
some new contacts with folks there as well and learned some real interesting
stuff.
The March workshop will be held on Wednesday 15 (the third Wednesday of the
month!). The topic will be Small Scale Irrigation Techniques. It will be at
the Dennis Wicker convention Center in Sanford beginning at 5:00pm.
The April workshop is tentively scheduled for 4/19 with the topic covering
low tech season extension techniques and experiences. This one, we are
planning to have on one of the area's farms to get some hands-on information.
Later workshop sessions will include small fruit and nut production,
alternative crops: ethnic and heirloom vegetables, goat and lamb production,
rare breed livestock and poultry raising, and more.
ATTENTION SMALL FARMERS
Organizational meeting for growers interested in forming a grower's "Marketing Cooperative"
through the
production of garlic and lettuce/salad mix.
Looking for committed farmers that will put the time and effort needed to grow a quality
product. Size of
individual production is not important. That is why we are looking at a marketing cooperative.
Quality is the key,
quantity will be made up by the number of farmers involved. Organic certification will be
necessary for certain
marketing accounts.
Experienced and new growers alike are encouraged to participate.
When? Thursday March 9 7:00pm
Where? Chatham Co. Cooperative Extension Ag. Offices
45 South St. Pittsboro, NC 27312
contact Robert Hadad for info: 919-542-8202
The use of brand names and any mention or listing of commercial
products or services
in this publication does not imply endorsement by North Carolina State
University, North
Carolina A&T state University or North Carolina Cooperative Extension
nor discrimination
against similar products or services not mentioned.
If I may be of further service to you, please contact me at the
following number:
Phone:(919)542-8202; FAX (919) 542-8246
If you have something to list in the next newsletter, send it
to me by the first of
the month before the next issue comes out. Address it to: P. O. Box 279, Pittsboro, NC
27312.
Sincerely,
Robert Hadad
Assistant Agriculture Agent
Return to Chatham County Home Page
This page was created by
Paulette Thomas
Secretary II
Date Created 3/14/00.
WHAT DOES SUSTAINABLE MEAN TO YOU?