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by Steve Solomon
Making Superior Compost
The potency of composts can vary greatly.
Most municipal solid waste compost has a high carbon to nitrogen ratio and when tilled
into soil temporarily provokes the opposite of a good growth response until soil
animals and microorganisms consume most of the undigested paper. But if low-grade
compost is used as a surface mulch on ornamentals, the results are usually quite
satisfactory even if unspectacular.
If the aim of your own composting is
to conveniently dispose of yard waste and kitchen garbage, the information in the
first half of the book is all you need to know. If you need compost to make something
that dependably GROWS plants like it was fertilizer, then this chapter is for you.
A Little History
Before the twentieth century, the fertilizers
market gardeners used were potent manures and composts. The vegetable gardens of
country folk also received the best manures and composts available while the field
crops got the rest. So I've learned a great deal from old farming and market gardening
literature about using animal manures. In previous centuries, farmers classified
manures by type and purity. There was "long" and "short" manure,
and then, there was the supreme plant growth stimulant, chicken manure.
Chicken manure was always highly prized
but usually in short supply because preindustrial fowl weren't caged in factories
or permanently locked in hen houses and fed scientifically formulated mixes. The
chicken breed of that era was usually some type of bantam, half-wild, broody, protective
of chicks, and capable of foraging. A typical pre-1900 small-scale chicken management
system was to allow the flock free access to hunt their own meals in the barnyard
and orchard, luring them into the coop at dusk with a bit of grain where they were
protected from predators while sleeping helplessly. Some manure was collected from
the hen house but most of it was dropped where it could not be gathered. The daily
egg hunt was worth it because, before the era of pesticides, having chickens range
through the orchard greatly reduced problems with insects in fruit.
The high potency of chicken manure
derives from the chickens' low C/N diet: worms, insects, tender shoots of new grass,
and other proteinaceous young greens and seeds. Twentieth-century chickens "living"
in egg and meat factories must still be fed low C/N foods, primarily grains, and
their manure is still potent. But anyone who has savored real free-range eggs with
deep orange yokes from chickens on a proper diet cannot be happy with what passes
for "eggs" these days.
Fertilizing with pure chicken manure
is not very different than using ground cereal grains or seed meals. It is so concentrated
that it might burn plant leaves like chemical fertilizer does and must be applied
sparingly to soil. It provokes a marked and vigorous growth response. Two or three
gallons of dry, pure fresh chicken manure are sufficient nutrition to GROW about
100 square feet of vegetables in raised beds to the maximum.
Exclusively incorporating pure chicken
manure into a vegetable garden also results in rapid humus loss, just as though chemical
fertilizers were used. Any fertilizing substance with a C/N below that of stabilized
humus, be it a chemical or a natural substance, accelerates the decline in soil organic
matter. That is because nitrate nitrogen, the key to constructing all protein, is
usually the main factor limiting the population of soil microorganisms. When the
nitrate level of soil is significantly increased, microbe populations increase proportionately
and proceeds to eat organic matter at an accelerated rate.
That is why small amounts of chemical
fertilizer applied to soil that still contains a reasonable amount of humus has such
a powerful effect. Not only does the fertilizer itself stimulate the growth of plants,
but fertilizer increases the microbial population. More microbes accelerate the breakdown
of humus and even more plant nutrients are released as organic matter decays. And
that is why holistic farmers and gardeners mistakenly criticize chemical fertilizers
as being directly destructive of soil microbes. Actually, all fertilizers, chemical
or organic, indirectly harm soil life, first increasing their populations
to unsustainable levels that drop off markedly once enough organic matter has been
eaten. Unless, of course, the organic matter is replaced.
Chicken manure compost is another matter.
Mix the pure manure with straw, sawdust, or other bedding, compost it and, depending
on the amount and quantity of bedding used and the time allowed for decomposition
to occur, the resultant C/N will be around 12:1 or above. Any ripened compost around
12:1 still will GROW plants beautifully. Performance drops off as the C/N increases.
Since chicken manure was scarce, most
pre-twentieth century market gardeners depended on seemingly unlimited supplies of
"short manure," generally from horses. The difference between the "long"
and the "short" manure was bedding. Long manure contained straw from the
stall while short manure was pure street sweepings without adulterants. Hopefully,
the straw portion of long manure had absorbed a quantity of urine.
People of that era knew the fine points
of hay quality as well as people today know their gasoline. Horses expected to do
a day's work were fed on grass or grass/clover mixes that had been cut and dried
while they still had a high protein content. Leafy hay was highly prized while hay
that upon close inspection revealed lots of stems and seed heads would be rejected
by a smart buyer. The working horse's diet was supplemented with a daily ration of
grain. Consequently, uncomposted fresh short manure probably started out with a C/N
around 15:1. However, don't count on anything that good from horses these days. Most
horses aren't worked daily so their fodder is often poor. Judging from the stemmy,
cut-too-late grass hay our local horses have to try to survive on, if I could find
bedding-free horse manure it would probably have a C/N more like 20:1. Manure from
physically fit thoroughbred race horses is probably excellent.
Using fresh horse manure in soil gave
many vegetables a harsh flavor so it was first composted by mixing in some soil (a
good idea because otherwise a great deal of ammonia would escape the heap). Market
gardeners raising highly demanding crops like cauliflower and celery amended composted
short manure by the inches-thick layer. Lesser nutrient-demanding crops like snap
beans, lettuce, and roots followed these intensively fertilized vegetables without
Long manures containing lots of straw
were considered useful only for field crops or root vegetables. Wise farmers conserved
the nitrogen and promptly composted long manures. After heating and turning the resulting
C/N would probably be in a little below 20:1. After tilling it in, a short period
of time was allowed while the soil digested this compost before sowing seeds. Lazy
farmers spread raw manure load by load as it came from the barn and tilled it in
once the entire field was covered. This easy method allows much nitrogen to escape
as ammonia while the manure dries in the sun. Commercial vegetable growers had little
use for long manure.
One point of this brief history lesson
is GIGO: garbage in, garbage out. The finished compost tends to have a C/N that is
related to the ingredients that built the heap. Growers of vegetables will wisely
Anyone interested in learning more
about preindustrial market gardening might ask their librarian to seek out a book
called French Gardening by Thomas Smith, published in London about 1905. This
fascinating little book was written to encourage British market gardeners to imitate
the Parisian marciér, who skillfully earned top returns growing out-of-season
produce on intensive, double-dug raised beds, often under glass hot or cold frames.
Our trendy American Biodynamic French Intensive gurus obtained their inspiration
from England through this tradition.
Curing the Heap
The easiest and most sure-fire improver
of compost quality is time. Making a heap with predominantly low C/N materials inevitably
results in potent compost if nitrate loss is kept to a minimum. But the C/N of almost
any compost heap, even one starting with a high C/N will eventually lower itself.
The key word here is eventually. The most dramatic decomposition occurs during
the first few turns when the heap is hot. Many people, including writers of garden
books, mistakenly think that the composting ends when the pile cools and the material
no longer resembles what made up the heap. This is not true. As long as a compost
heap is kept moist and is turned occasionally, it will continue to decompose. "Curing"
or "ripening" are terms used to describe what occurs once heating is over.
A different ecology of microorganisms
predominates while a heap is ripening. If the heap contains 5 to 10 percent soil,
is kept moist, is turned occasionally so it stays aerobic, and has a complete mineral
balance, considerable bacterial nitrogen fixation may occur.
Most gardeners are familiar with the
microbes that nodulate the roots of legumes. Called rhizobia, these bacteria are
capable of fixing large quantities of nitrate nitrogen in a short amount of time.
Rhizobia tend to be inactive during hot weather because the soil itself is supplying
nitrates from the breakdown of organic matter. Summer legume crops, like cowpeas
and snap beans, tend to be net consumers of nitrates, not makers of more nitrates
than they can use. Consider this when you read in carelessly researched garden books
and articles about the advantages of interplanting legumes with other crops because
they supposedly generate nitrates that "help" their companions.
But during spring or fall when lowered
soil temperatures retard decomposition, rhizobia can manufacture from 80 to 200 pounds
of nitrates per acre. Peas, clovers, alfalfa, vetches, and fava beans can all make
significant contributions of nitrate nitrogen and smart farmers prefer to grow their
nitrogen by green manuring legumes. Wise farmers also know that this nitrate, though
produced in root nodules, is used by legumes to grow leaf and stem. So the entire
legume must be tilled in if any net nitrogen gain is to be realized. This wise practice
simultaneously increases organic matter.
Rhizobia are not capable of being active
in compost piles, but another class of microbes is. Called azobacteria, these free-living
soil dwellers also make nitrate nitrogen. Their contribution is not potentially as
great as rhizobia, but no special provision must be made to encourage azobacteria
other than maintaining a decent level of humus for them to eat, a balanced mineral
supply that includes adequate calcium, and a soil pH between 5.75 and 7.25. A high-yielding
crop of wheat needs 60-80 pounds of nitrates per acre. Corn and most vegetables can
use twice that amount. Azobacteria can make enough for wheat, though an average nitrate
contribution under good soil conditions might be more like 30-50 pounds per year.
Once a compost heap has cooled, azobacteria
will proliferate and begin to manufacture significant amounts of nitrates, steadily
lowering the C/N. And carbon never stops being digested, further dropping the C/N.
The rapid phase of composting may be over in a few months, but ripening can be allowed
to go on for many more months if necessary.
Feeding unripened compost to worms
is perhaps the quickest way to lower C/N and make a potent soil amendment. Once the
high heat of decomposition has passed and the heap is cooling, it is commonly invaded
by redworms, the same species used for vermicomposting kitchen garbage. These worms
would not be able to eat the high C/N material that went into a heap, but after heating,
the average C/N has probably dropped enough to be suitable for them.
The municipal composting operation
at Fallbrook, California makes clever use of this method to produce a smaller amount
of high-grade product out of a larger quantity of low-grade ingredients. Mixtures
of sewage sludge and municipal solid waste are first composted and after cooling,
the half-done high C/N compost is shallowly spread out over crude worm beds and kept
moist. More crude compost is added as the worms consume the waste, much like a household
worm box. The worm beds gradually rise. The lower portion of these mounds is pure
castings while the worm activity stays closer to the surface where food is available.
When the beds have grown to about three feet tall, the surface few inches containing
worms and undigested food are scraped off and used to form new vermicomposting beds.
The castings below are considered finished compost. By laboratory analysis, the castings
contain three or four times as much nitrogen as the crude compost being fed to the
The marketplace gives an excellent
indicator of the difference between their crude compost and the worm casts. Even
though Fallbrook is surrounded by large acreages devoted to citrus orchards and row
crop vegetables, the municipality has a difficult time disposing of the crude product.
But their vermicompost is in strong demand.
Sir Albert Howard's Indore Method
Nineteenth-century farmers and market
gardeners had much practical knowledge about using manures and making composts that
worked like fertilizers, but little was known about the actual microbial process
of composting until our century. As information became available about compost ecology,
one brilliant individual, Sir Albert Howard, incorporated the new science of soil
microbiology into his composting and by patient experiment learned how to make superior
During the 1920s, Albert Howard was
in charge of a government research farm at Indore, India. At heart a Peace Corps
volunteer, he made Indore operate like a very representative Indian farm, growing
all the main staples of the local agriculture: cotton, sugar cane, and cereals. The
farm was powered by the same work oxen used by the surrounding farmers. It would
have been easy for Howard to demonstrate better yields through high technology by
buying chemical fertilizers or using seed meal wastes from oil extraction, using
tractors, and growing new, high-yielding varieties that could make use of more intense
soil nutrition. But these inputs were not affordable to the average Indian farmer
and Howard's purpose was to offer genuine help to his neighbors by demonstrating
methods they could easily afford and use.
In the beginning of his work at Indore,
Howard observed that the district's soils were basically fertile but low in organic
matter and nitrogen. This deficiency seemed to be due to traditionally wasteful practices
concerning manures and agricultural residues. So Howard began developing methods
to compost the waste products of agriculture, making enough high-quality fertilizer
to supply the entire farm. Soon, Indore research farm was enjoying record yields
without having insect or disease problems, and without buying fertilizer or commercial
seed. More significantly, the work animals, fed exclusively on fodder from Indore's
humus-rich soil, become invulnerable to cattle diseases. Their shining health and
fine condition became the envy of the district.
Most significant, Howard contended
that his method not only conserved the nitrogen in cattle manure and crop waste,
not only conserved the organic matter the land produced, but also raised the processes
of the entire operation to an ecological climax of maximized health and production.
Conserving the manure and composting the crop waste allowed him to increase the soil's
organic matter which increased the soil's release of nutrients from rock particles
that further increased the production of biomass which allowed him to make even more
compost and so on. What I have just described is not surprising, it is merely a variation
on good farming that some humans have known about for millennia.
What was truly revolutionary was Howard's
contention about increasing net nitrates. With gentle understatement, Howard asserted
that his compost was genuinely superior to anything ever known before. Indore compost
had these advantages: no nitrogen or organic matter was lost from the farm through
mishandling of agricultural wastes; the humus level of the farm's soils increased
to a maximum sustainable level; and, the amount of nitrate nitrogen in the finished
compost was higher than the total amount of nitrogen contained in the materials that
formed the heap. Indore compost resulted in a net gain of nitrate nitrogen. The
compost factory was also a biological nitrate factory.
Howard published details of the Indore
method in 1931 in a slim book called The Waste Products of Agriculture. The
widely read book brought him invitations to visit plantations throughout the British
Empire. It prompted farmers world-wide to make compost by the Indore method. Travel,
contacts, and new awareness of the problems of European agriculture were responsible
for Howard's decision to create an organic farming and gardening movement.
Howard repeatedly warned in The
Waste Products of Agriculture that if the underlying fundamentals of his process
were altered, superior results would not occur. That was his viewpoint in 1931. However,
humans being what we are, it does not seem possible for good technology to be broadcast
without each user trying to improve and adapt it to their own situation and understanding.
By 1940, the term "lndore compost" had become a generic term for any kind
of compost made in a heap without the use of chemicals, much as "Rototiller"
has come to mean any motor-driven rotarytiller.
Howard's 1931 concerns were correct--almost
all alterations of the original Indore system lessened its value--but Howard of 1941
did not resist this dilutive trend because in an era of chemical farming any compost
was better than no compost, any return of humus better than none.
Still, I think it is useful to go back
to the Indore research farm of the 1920s and to study closely how Albert Howard once
made the world's finest compost, and to encounter this great man's thoughts before
he became a crusading ideologue, dead set against any use of agricultural chemicals.
A great many valuable lessons are still contained in The Waste Products of Agriculture.
Unfortunately, even though many organic gardeners are familiar with the later
works of Sir Albert Howard the reformer, Albert Howard the scientist and researcher,
who wrote this book, is virtually unknown today.
At Indore, all available vegetable
material was composted, including manure and bedding straw from the cattle shed,
unconsumed crop residues, fallen leaves and other forest wastes, weeds, and green
manures grown specifically for compost making. All of the urine from the cattle shed-in
the form of urine earth--and all wood ashes from any source on the farm were also
included. Being in the tropics, compost making went on year-round. Of the result,
Howard stated that
"The product is a finely divided leafmould,
of high nitrifying power, ready for immediate use [without temporarily inhibiting
plant growth]. The fine state of division enables the compost to be rapidly incorporated
and to exert its maximum influence on a very large area of the internal surface of
Howard stressed that for the Indore method
to work reliably the carbon to nitrogen ratio of the material going into the heap
must always be in the same range. Every time a heap was built the same assortment
of crop wastes were mixed with the same quantities of fresh manure and urine earth.
As with my bread-baking analogy, Howard insured repeatability of ingredients.
Any hard, woody materials--Howard called
them "refractory"--must be thoroughly broken up before composting, otherwise
the fermentation would not be vigorous, rapid, and uniform throughout the process.
This mechanical softening up was cleverly accomplished without power equipment by
spreading tough crop wastes like cereal straw or pigeon pea and cotton stalks out
over the farm roads, allowing cartwheels, the oxens' hooves, and foot traffic to
break them up.
Decomposition must be rapid and aerobic,
but not too aerobic. And not too hot. Quite intentionally, Indore compost piles were
not allowed to reach the highest temperatures that are possible. During the first
heating cycle, peak temperatures were about 140°. After two weeks, when the
first turn was made, temperatures had dropped to about 125°, and gradually declined
from there. Howard cleverly restricted the air supply and thermal mass so as to "bank
the fires" of decomposition. This moderation was his key to preventing loss
of nitrogen. Provisions were made to water the heaps as necessary, to turn them several
times, and to use a novel system of mass inoculation with the proper fungi and bacteria.
I'll shortly discuss each of these subjects in detail. Howard was pleased that there
was no need to accept nitrogen loss at any stage and that the reverse should happen.
Once the C/N had dropped sufficiently, the material was promptly incorporated into
the soil where nitrate nitrogen will be best preserved. But the soil is not capable
of doing two jobs at once. It can't digest crude organic matter and simultaneously
nitrify humus. So compost must be finished and completely ripe when it was tilled
in so that:
". . . there must be no serious competition
between the last stages of decay of the compost and the work of the soil in growing
the crop. This is accomplished by carrying the manufacture of humus up to the point
when nitrification is about to begin. In this way the Chinese principle of dividing
the growing of a crop into two separate processes --(1) the preparation of the food
materials outside the field, and (2) the actual growing of the crop-can be introduced
into general agricultural practice."
And because he actually lived on a farm,
Howard especially emphasized that composting must be sanitary and odorless and that
flies must not be allowed to breed in the compost or around the work cattle. Country
life can be quite idyllic--without flies.
The Indore Compost Factory
At Indore, Howard built a covered,
open-sided, compost-making factory that sheltered shallow pits, each 30 feet long
by 14 feet wide by 2 feet deep with sloping sides. The pits were sufficiently spaced
to allow loaded carts to have access to all sides of any of them and a system of
pipes brought water near every one. The materials to be composted were all stored
adjacent to the factory. Howard's work oxen were conveniently housed in the next
Soil and Urine Earth
Howard had been raised on an English
farm and from childhood he had learned the ways of work animals and how to make them
comfortable. So, for the ease of their feet, the cattle shed and its attached, roofed
loafing pen had earth floors. All soil removed from the silage pits, dusty sweepings
from the threshing floors, and silt from the irrigation ditches were stored near
the cattle shed and used to absorb urine from the work cattle. This soil was spread
about six inches deep in the cattle stalls and loafing pen. About three times a year
it was scraped up and replaced with fresh soil, the urine-saturated earth then was
dried and stored in a special covered enclosure to be used for making compost .
The presence of this soil in the heap
was essential. First, the black soil of Indore was well-supplied with calcium, magnesium,
and other plant nutrients. These basic elements prevented the heaps from becoming
overly acid. Additionally, the clay in the soil was uniquely incorporated into the
heap so that it coated everything. Clay has a strong ability to absorb ammonia, preventing
nitrogen loss. A clay coating also holds moisture. Without soil, "an even and
vigorous mycelial growth is never quickly obtained." Howard said "the fungi
are the storm troops of the composting process, and must be furnished with all the
armament they need."
Crop wastes were protected from moisture,
stored dry under cover near the compost factory. Green materials were first withered
in the sun for a few days before storage. Refractory materials were spread on the
farm's roads and crushed by foot traffic and cart wheels before stacking. All these
forms of vegetation were thinly layered as they were received so that the dry storage
stacks became thoroughly mixed. Care was taken to preserve the mixing by cutting
vertical slices out of the stacks when vegetation was taken to the compost pits.
Howard said the average C/N of this mixed vegetation was about 33:1. Every compost
heap made year-round was built with this complex assortment of vegetation having
the same properties and the same C/N.
Special preliminary treatment was given
to hard, woody materials like sugarcane, millet stumps, wood shavings and waste paper.
These were first dumped into an empty compost pit, mixed with a little soil, and
kept moist until they softened. Or they might be soaked in water for a few days and
then added to the bedding under the work cattle. Great care was taken when handling
the cattle's bedding to insure that no flies would breed in it.
Though crop wastes and urine-earth
could be stored dry for later use, manure, the key ingredient of Indore compost,
had to be used fresh. Fresh cow dung contains bacteria from the cow's rumen that
is essential to the rapid decomposition of cellulose and other dry vegetation. Without
their abundant presence composting would not begin as rapidly nor proceed as surely.
Charging the Compost Pits
Every effort was made to fill a pit
to the brim within one week. If there wasn't enough material to fill an entire pit
within one week, then a portion of one pit would be filled to the top. To preserve
good aeration, every effort was made to avoid stepping on the material while filling
the pit. As mixtures of manure and bedding were brought out from the cattle shed
they were thinly layered atop thin layers of mixed vegetation brought in from the
dried reserves heaped up adjacent to the compost factory. Each layer was thoroughly
wet down with a clay slurry made of three ingredients: water, urine-earth, and actively
decomposing material from an adjacent compost pit that had been filled about two
weeks earlier. This insured that every particle within the heap was moist and was
coated with nitrogen-rich soil and the microorganisms of decomposition. Today, we
would call this practice "mass inoculation."
Pits Versus Heaps
India has two primary seasons. Most
of the year is hot and dry while the monsoon rains come from dune through September.
During the monsoon, so much water falls so continuously that the earth becomes completely
saturated. Even though the pits were under a roof, they would fill with water during
this period. So in the monsoon, compost was made in low heaps atop the ground. Compared
to the huge pits, their dimensions were smaller than you would expect: 7 x 7 feet
at the top, 8 x 8 feet at the base and no more than 2 feet high. When the rains started,
any compost being completed in pits was transferred to above-ground heaps when it
Howard was accomplishing several things
by using shallow pits or low but very broad heaps. One, thermal masses were reduced
so temperatures could not reach the ultimate extremes possible while composting.
The pits were better than heaps because air flow was further reduced, slowing down
the fermentation, while their shallowness still permitted sufficient aeration. There
were enough covered pits to start a new heap every week.
Temperature Range in
|Age in days
||Temperature in °C
Period in days for each fall of 5i C
||No. of Days
Turning the compost was done
three times: To insure uniform decomposition, to restore moisture and air, and to
supply massive quantities of those types of microbes needed to take the composting
process to its next stage.
The first turn was at about sixteen
days. A second mass inoculation equivalent to a few wheelbarrows full of 30 day old
composting material was taken from an adjacent pit and spread thinly over the surface
of the pit being turned. Then, one half of the pit was dug out with a manure fork
and placed atop the first half. A small quantity of water was added, if needed to
maintain moisture. Now the compost occupied half the pit, a space about 15 x 14 and
was about three feet high, rising out of the earth about one foot. During the monsoons
when heaps were used, the above-ground piles were also mass inoculated and then turned
so as to completely mix the material, and as we do today, placing the outside material
in the core and vice-versa.
One month after starting, or about
two weeks after the first turn, the pit or heap would be turned again. More water
would be added. This time the entire mass would be forked from one half the pit to
the other and every effort would be made to fluff up the material while thoroughly
mixing it. And a few loads of material were removed to inoculate a 15-day-old pit.
Another month would pass, or about
two months after starting, and for the third time the compost would be turned and
then allowed to ripen. This time the material is brought out of the pit and piled
atop the earth so as to increase aeration. At this late stage there would be no danger
of encouraging high temperatures but the increased oxygen facilitated nitrogen fixation.
The contents of several pits might be combined to form a heap no larger than 10 x
10 at the base, 9 x 9 on top, and no more than 3-1/2 feet high. Again, more water
might be added. Ripening would take about one month. Howard's measurements showed
that after a month's maturation the finished compost should be used without delay
or precious nitrogen would be lost. However, keep in mind when considering this brief
ripening period that the heap was already as potent as it could become. Howard's
problem was not further improving the C/N, it was conservation of nitrogen.
The Superior Value of Indore Compost.
Howard said that finished Indore compost
was twice as rich in nitrogen as ordinary farmyard manure and that his target was
compost with a C/N of 10:1. Since it was long manure he was referring to, let's assume
that the C/N of a new heap started at 25:1.
The C/N of vegetation collected during
the year is highly variable. Young grasses and legumes are very high in nitrogen,
while dried straw from mature plants has a very high C/N. If compost is made catch-as-catch-can
by using materials as they come available, then results will be highly erratic. Howard
had attempted to make composts of single vegetable materials like cotton residues,
cane trash, weeds, fresh green sweet clover, or the waste of field peas. These experiments
were always unsatisfactory. So Howard wisely mixed his vegetation, first withering
and drying green materials by spreading them thinly in the sun to prevent their premature
decomposition, and then taking great care to preserve a uniform mixture of vegetation
types when charging his compost pits. This strategy can be duplicated by the home
gardener. Howard was surprised to discover that he could compost all the crop waste
he had available with only half the urine earth and about one-quarter of the oxen
manure he had available. But fresh manure and urine earth were essential.
During the 1920s a patented process
for making compost with a chemical fertilizer called Adco was in vogue and Howard
tried it. Of using chemicals he said:
"The weak point of Adco is that it
does nothing to overcome one of the great difficulties in composting, namely the
absorption of moisture in the early stages. In hot weather in India, the Adco pits
lose moisture so rapidly that the fermentation stops, the temperature becomes uneven
and then falls. When, however, urine earth and cow-dung are used, the residues become
covered with a thin colloidal film, which not only retains moisture but contains
combined nitrogen and minerals required by the fungi. This film enables the moisture
to penetrate the mass and helps the fungi to establish themselves. Another disadvantage
of Adco is that when this material is used according to the directions, the carbon-nitrogen
ratio of the final product is narrower than the ideal 10:1. Nitrogen is almost certain
to be lost before the crop can make use of it"
Fresh cow manure contains digestive enzymes
and living bacteria that specialize in cellulose decomposition. Having a regular
supply of this material helped initiate decomposition without delay. Contributing
large quantities of actively growing microorganisms through mass inoculation with
material from a two-week-old pile also helped. The second mass inoculation at two
weeks, with material from a month-old heap provided a large supply of the type of
organisms required when the heap began cooling. City gardeners without access to
fresh manure may compensate for this lack by imitating Howard's mass inoculation
technique, starting smaller amounts of compost in a series of bins and mixing into
each bin a bit of material from the one further along at each turning. The passive
backyard composting container automatically duplicates this advantage. It simultaneously
contains all decomposition stages and inoculates the material above by contact with
more decomposed material below. Using prepared inoculants in a continuous composting
bin is unnecessary.
City gardeners cannot readily obtain
urine earth. Nor are American country gardeners with livestock likely to be willing
to do so much work. Remember that Howard used urine earth for three reasons. One,
it contained a great deal of nitrogen and improved the starting C/N of the heap.
Second, it is thrifty. Over half the nutrient content of the food passing through
cattle is discharged in the urine. But, equally important, soil itself was beneficial
to the process. Of this Howard said, "[where] there may be insufficient dung
and urine earth for converting large quantities of vegetable wastes which are available,
the shortage may be made up by the use of nitrate of soda . . . If such artificials
are employed, it will be a great advantage to make use of soil." I am sure he
would have made very similar comments about adding soil when using chicken manure,
or organic concentrates like seed meals, as cattle manure substitutes.
Control of the air supply is the most
difficult part of composting. First, the process must stay aerobic. That is one reason
that single-material heaps fail because they tend to pack too tightly. To facilitate
air exchange, the pits or heaps were never more than two feet deep. Where air was
insufficient (though still aerobic) decay is retarded but worse, a process called
denitrification occurs in which nitrates and ammonia are biologically broken down
into gasses and permanently lost. Too much manure and urine-earth can also interfere
with aeration by making the heap too heavy, establishing anaerobic conditions. The
chart illustrates denitrification caused by insufficient aeration compared to turning
the composting process into a biological nitrate factory with optimum aeration.
Making Indore Compost in Deep and Shallow Pits
||Pit 4 feet deep
||Pit 2 feet deep
Amount of material (lb. wet) in pit at start
|Total nitrogen (lb) at start
|Total nitrogen at end
|Loss or gain of nitrogen (lb)
|Percentage loss or gain of nitrogen
Finally, modern gardeners might reconsider
limiting temperature during composting. India is a very warm climate with balmy nights
most of the year. Heaps two or three feet high will achieve an initial temperature
of about 145°. The purchase of a thermometer with a long probe and a little
experimentation will show you the dimensions that will more-or-less duplicate Howard's
temperature regimes in your climate with your materials.
Howard's technique of mass inoculation
with large amounts of biologically active material from older compost heaps speeds
and directs decomposition. It supplies large numbers of the most useful types of
microorganisms so they dominate the heap's ecology before other less desirable types
can establish significant populations. I can't imagine how selling mass inoculants
could be turned into a business.
But just imagine that seeding a new
heap with tiny amounts of superior microorganisms could speed initial decomposition
and result in a much better product. That could be a business. Such an approach
is not without precedent. Brewers, vintners, and bread makers all do that. And ever
since composting became interesting to twentieth-century farmers and gardeners, entrepreneurs
have been concocting compost starters that are intended to be added by the ounce(s)
to the cubic yard.
Unlike the mass inoculation used at
Indore, these inoculants are a tiny population compared to the microorganisms already
present in any heap. In that respect, inoculating compost is very different than
beer, wine, or bread. With these food products there are few or no microorganisms
at the start. The inoculant, small as it might be, still introduces millions of times
more desirable organisms than those wild types that might already be present.
But the materials being assembled into
a new compost heap are already loaded with microorganism. As when making sauerkraut,
what is needed is present at the start. A small packet of inoculant is not likely
to introduce what is not present anyway. And the complex ecology of decomposition
will go through its inevitable changes as the microorganisms respond to variations
in temperature, aeration, pH, etc.
This is one area of controversy where
I am comfortable seeking the advice of an expert. In this case, the authority is
Clarence Golueke, who personally researched and developed U.C. fast composting in
the early 1950s, and who has been developing municipal composting systems ever since.
The bibliography of this book lists two useful works by Golueke.
Golueke has run comparison tests of
compost starters of all sorts because, in his business, entrepreneurs are constantly
attempting to sell inoculants to municipal composting operations. Of these vendors,
Golueke says with thinly disguised contempt:
"Most starter entrepreneurs include
enzymes when listing the ingredients of their products. The background for this inclusion
parallels the introduction of purportedly advanced versions of starters-i.e., "advanced"
in terms of increased capacity, utility and versatility. Thus in the early 1950's
(when [I made my] appearance on the compost scene), starters were primarily microbial
and references to identities of constituent microbes were very vague. References
to enzymes were extremely few and far between. As early ("pioneer") researchers
began to issue formal and informal reports on microbial groups (e.g., actinomycetes)
observed by them, they also began to conjecture on the roles of those microbial groups
in the compost process. The conjectures frequently were accompanied by surmises about
the part played by enzymes.
Coincidentally, vendors of starters
in vogue at the time began to claim that their products included the newly reported
microbial groups as well as an array of enzymes. For some reason, hormones were attracting
attention at the time, and so most starters were supposedly laced with hormones.
In time, hormones began to disappear from the picture, whereas enzymes were given
a billing parallel to that accorded to the microbial component."
Golueke has worked out methods of testing
starters that eliminates any random effects and conclusively demonstrates their result.
Inevitably, and repeatedly, he found that there was no difference between using a
starter and not using one. And he says, "Although anecdotal accounts of success
due to the use of particular inoculum are not unusual in the popular media, we have
yet to come across unqualified accounts of successes in the refereed scientific and
technical literature. I use a variation of mass inoculation when making compost.
While building a new heap, I periodically scrape up and toss in a few shovels of
compost and soil from where the previous pile was made. Frankly, if I did not do
this I don't think the result would be any worse.
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