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 the soil."

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 a.s.sortment of crop wastes were mixed with the same quant.i.ties of fresh manure and urine earth. As with my bread-baking a.n.a.logy, 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 degree.

After two weeks, when the first turn was made, temperatures had dropped to about 125 degree, and gradually declined from there.

Howard cleverly restricted the air supply and thermal ma.s.s 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 ma.s.s 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 compet.i.tion 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 s.p.a.ced 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 building.

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 sc.r.a.ped 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

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 a.s.sortment 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.

Manure

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 "ma.s.s 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 was turned.

Howard was accomplishing several things by using shallow pits or low but very broad heaps. One, thermal ma.s.ses 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 Normal Pit

Age in days Temperature in degree C

3 63 4 60 6 58 11 55 12 53 13 49 14 49

_First Turn_

18 49 20 51 22 48 24 47 29 46

_Second Turn_

37 49 38 45 40 40 43 39 57 39

_Third Turn_

61 41 66 39 76 38 82 36 90 33

Period in days for each fall of 5i C

Temperature Range No. of Days

65 degree-60 degree 4 60 degree-55 degree 7 55 degree-50 degree 1 50 degree-45 degree 25 45 degree-40 degree 2 40 degree-35 degree 44 35 degree-30 degree 14

Total 97 days

Turning

_Turning the compost_ was done three times: To insure uniform decomposition, to restore moisture and air, and to supply ma.s.sive quant.i.ties 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 ma.s.s 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 quant.i.ty of water was added, if needed to maintain moisture. Now the compost occupied half the pit, a s.p.a.ce 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 ma.s.s 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 ma.s.s 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 pa.s.s, 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 a.s.sume 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 gra.s.ses 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 ma.s.s 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"