_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.