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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 tilledinto soil temporarily provokes the opposite of a good growth response until soilanimals and microorganisms consume most of the undigested paper. But if low-gradecompost is used as a surface mulch on ornamentals, the results are usually quitesatisfactory even if unspectacular.
If the aim of your own composting isto conveniently dispose of yard waste and kitchen garbage, the information in thefirst half of the book is all you need to know. If you need compost to make somethingthat dependably GROWS plants like it was fertilizer, then this chapter is for you.
A Little History
Before the twentieth century, the fertilizersmarket gardeners used were potent manures and composts. The vegetable gardens ofcountry folk also received the best manures and composts available while the fieldcrops got the rest. So I've learned a great deal from old farming and market gardeningliterature about using animal manures. In previous centuries, farmers classifiedmanures 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 prizedbut usually in short supply because preindustrial fowl weren't caged in factoriesor permanently locked in hen houses and fed scientifically formulated mixes. Thechicken breed of that era was usually some type of bantam, half-wild, broody, protectiveof chicks, and capable of foraging. A typical pre-1900 small-scale chicken managementsystem was to allow the flock free access to hunt their own meals in the barnyardand orchard, luring them into the coop at dusk with a bit of grain where they wereprotected from predators while sleeping helplessly. Some manure was collected fromthe hen house but most of it was dropped where it could not be gathered. The dailyegg hunt was worth it because, before the era of pesticides, having chickens rangethrough the orchard greatly reduced problems with insects in fruit.
The high potency of chicken manurederives 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, andtheir manure is still potent. But anyone who has savored real free-range eggs withdeep orange yokes from chickens on a proper diet cannot be happy with what passesfor "eggs" these days.
Fertilizing with pure chicken manureis not very different than using ground cereal grains or seed meals. It is so concentratedthat it might burn plant leaves like chemical fertilizer does and must be appliedsparingly to soil. It provokes a marked and vigorous growth response. Two or threegallons of dry, pure fresh chicken manure are sufficient nutrition to GROW about100 square feet of vegetables in raised beds to the maximum.
Exclusively incorporating pure chickenmanure into a vegetable garden also results in rapid humus loss, just as though chemicalfertilizers were used. Any fertilizing substance with a C/N below that of stabilizedhumus, be it a chemical or a natural substance, accelerates the decline in soil organicmatter. That is because nitrate nitrogen, the key to constructing all protein, isusually the main factor limiting the population of soil microorganisms. When thenitrate level of soil is significantly increased, microbe populations increase proportionatelyand proceeds to eat organic matter at an accelerated rate.
That is why small amounts of chemicalfertilizer applied to soil that still contains a reasonable amount of humus has sucha powerful effect. Not only does the fertilizer itself stimulate the growth of plants,but fertilizer increases the microbial population. More microbes accelerate the breakdownof humus and even more plant nutrients are released as organic matter decays. Andthat is why holistic farmers and gardeners mistakenly criticize chemical fertilizersas being directly destructive of soil microbes. Actually, all fertilizers, chemicalor organic, indirectly harm soil life, first increasing their populationsto unsustainable levels that drop off markedly once enough organic matter has beeneaten. 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, dependingon the amount and quantity of bedding used and the time allowed for decompositionto occur, the resultant C/N will be around 12:1 or above. Any ripened compost around12:1 still will GROW plants beautifully. Performance drops off as the C/N increases.
Since chicken manure was scarce, mostpre-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 thestall 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 pointsof hay quality as well as people today know their gasoline. Horses expected to doa day's work were fed on grass or grass/clover mixes that had been cut and driedwhile they still had a high protein content. Leafy hay was highly prized while haythat upon close inspection revealed lots of stems and seed heads would be rejectedby a smart buyer. The working horse's diet was supplemented with a daily ration ofgrain. Consequently, uncomposted fresh short manure probably started out with a C/Naround 15:1. However, don't count on anything that good from horses these days. Mosthorses 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 findbedding-free horse manure it would probably have a C/N more like 20:1. Manure fromphysically fit thoroughbred race horses is probably excellent.
Using fresh horse manure in soil gavemany vegetables a harsh flavor so it was first composted by mixing in some soil (agood idea because otherwise a great deal of ammonia would escape the heap). Marketgardeners raising highly demanding crops like cauliflower and celery amended compostedshort manure by the inches-thick layer. Lesser nutrient-demanding crops like snapbeans, lettuce, and roots followed these intensively fertilized vegetables withoutfurther compost.
Long manures containing lots of strawwere considered useful only for field crops or root vegetables. Wise farmers conservedthe nitrogen and promptly composted long manures. After heating and turning the resultingC/N would probably be in a little below 20:1. After tilling it in, a short periodof time was allowed while the soil digested this compost before sowing seeds. Lazyfarmers spread raw manure load by load as it came from the barn and tilled it inonce the entire field was covered. This easy method allows much nitrogen to escapeas ammonia while the manure dries in the sun. Commercial vegetable growers had littleuse for long manure.
One point of this brief history lessonis GIGO: garbage in, garbage out. The finished compost tends to have a C/N that isrelated to the ingredients that built the heap. Growers of vegetables will wiselytake note.
Anyone interested in learning moreabout preindustrial market gardening might ask their librarian to seek out a bookcalled French Gardening by Thomas Smith, published in London about 1905. Thisfascinating little book was written to encourage British market gardeners to imitatethe Parisian marciér, who skillfully earned top returns growing out-of-seasonproduce on intensive, double-dug raised beds, often under glass hot or cold frames.Our trendy American Biodynamic French Intensive gurus obtained their inspirationfrom England through this tradition.
Curing the Heap
The easiest and most sure-fire improverof compost quality is time. Making a heap with predominantly low C/N materials inevitablyresults in potent compost if nitrate loss is kept to a minimum. But the C/N of almostany 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 duringthe first few turns when the heap is hot. Many people, including writers of gardenbooks, mistakenly think that the composting ends when the pile cools and the materialno longer resembles what made up the heap. This is not true. As long as a compostheap 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 microorganismspredominates 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 mineralbalance, considerable bacterial nitrogen fixation may occur.
Most gardeners are familiar with themicrobes that nodulate the roots of legumes. Called rhizobia, these bacteria arecapable 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 supplyingnitrates from the breakdown of organic matter. Summer legume crops, like cowpeasand snap beans, tend to be net consumers of nitrates, not makers of more nitratesthan they can use. Consider this when you read in carelessly researched garden booksand articles about the advantages of interplanting legumes with other crops becausethey supposedly generate nitrates that "help" their companions.
But during spring or fall when loweredsoil temperatures retard decomposition, rhizobia can manufacture from 80 to 200 poundsof nitrates per acre. Peas, clovers, alfalfa, vetches, and fava beans can all makesignificant contributions of nitrate nitrogen and smart farmers prefer to grow theirnitrogen by green manuring legumes. Wise farmers also know that this nitrate, thoughproduced in root nodules, is used by legumes to grow leaf and stem. So the entirelegume must be tilled in if any net nitrogen gain is to be realized. This wise practicesimultaneously increases organic matter.
Rhizobia are not capable of being activein compost piles, but another class of microbes is. Called azobacteria, these free-livingsoil dwellers also make nitrate nitrogen. Their contribution is not potentially asgreat as rhizobia, but no special provision must be made to encourage azobacteriaother than maintaining a decent level of humus for them to eat, a balanced mineralsupply that includes adequate calcium, and a soil pH between 5.75 and 7.25. A high-yieldingcrop of wheat needs 60-80 pounds of nitrates per acre. Corn and most vegetables canuse twice that amount. Azobacteria can make enough for wheat, though an average nitratecontribution under good soil conditions might be more like 30-50 pounds per year.
Once a compost heap has cooled, azobacteriawill proliferate and begin to manufacture significant amounts of nitrates, steadilylowering 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 allowedto go on for many more months if necessary.
Feeding unripened compost to wormsis perhaps the quickest way to lower C/N and make a potent soil amendment. Once thehigh heat of decomposition has passed and the heap is cooling, it is commonly invadedby redworms, the same species used for vermicomposting kitchen garbage. These wormswould 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 operationat Fallbrook, California makes clever use of this method to produce a smaller amountof high-grade product out of a larger quantity of low-grade ingredients. Mixturesof 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 keptmoist. More crude compost is added as the worms consume the waste, much like a householdworm box. The worm beds gradually rise. The lower portion of these mounds is purecastings 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 containingworms and undigested food are scraped off and used to form new vermicomposting beds.The castings below are considered finished compost. By laboratory analysis, the castingscontain three or four times as much nitrogen as the crude compost being fed to theworms.
The marketplace gives an excellentindicator of the difference between their crude compost and the worm casts. Eventhough Fallbrook is surrounded by large acreages devoted to citrus orchards and rowcrop 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 marketgardeners had much practical knowledge about using manures and making composts thatworked like fertilizers, but little was known about the actual microbial processof composting until our century. As information became available about compost ecology,one brilliant individual, Sir Albert Howard, incorporated the new science of soilmicrobiology into his composting and by patient experiment learned how to make superiorcompost
During the 1920s, Albert Howard wasin charge of a government research farm at Indore, India. At heart a Peace Corpsvolunteer, he made Indore operate like a very representative Indian farm, growingall the main staples of the local agriculture: cotton, sugar cane, and cereals. Thefarm was powered by the same work oxen used by the surrounding farmers. It wouldhave been easy for Howard to demonstrate better yields through high technology bybuying chemical fertilizers or using seed meal wastes from oil extraction, usingtractors, and growing new, high-yielding varieties that could make use of more intensesoil nutrition. But these inputs were not affordable to the average Indian farmerand Howard's purpose was to offer genuine help to his neighbors by demonstratingmethods 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 organicmatter and nitrogen. This deficiency seemed to be due to traditionally wasteful practicesconcerning manures and agricultural residues. So Howard began developing methodsto compost the waste products of agriculture, making enough high-quality fertilizerto supply the entire farm. Soon, Indore research farm was enjoying record yieldswithout having insect or disease problems, and without buying fertilizer or commercialseed. More significantly, the work animals, fed exclusively on fodder from Indore'shumus-rich soil, become invulnerable to cattle diseases. Their shining health andfine condition became the envy of the district.
Most significant, Howard contendedthat 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 processesof 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'sorganic matter which increased the soil's release of nutrients from rock particlesthat further increased the production of biomass which allowed him to make even morecompost and so on. What I have just described is not surprising, it is merely a variationon good farming that some humans have known about for millennia.
What was truly revolutionary was Howard'scontention about increasing net nitrates. With gentle understatement, Howard assertedthat his compost was genuinely superior to anything ever known before. Indore composthad these advantages: no nitrogen or organic matter was lost from the farm throughmishandling of agricultural wastes; the humus level of the farm's soils increasedto a maximum sustainable level; and, the amount of nitrate nitrogen in the finishedcompost was higher than the total amount of nitrogen contained in the materials thatformed the heap. Indore compost resulted in a net gain of nitrate nitrogen. Thecompost factory was also a biological nitrate factory.
Howard published details of the Indoremethod in 1931 in a slim book called The Waste Products of Agriculture. Thewidely read book brought him invitations to visit plantations throughout the BritishEmpire. It prompted farmers world-wide to make compost by the Indore method. Travel,contacts, and new awareness of the problems of European agriculture were responsiblefor Howard's decision to create an organic farming and gardening movement.
Howard repeatedly warned in TheWaste Products of Agriculture that if the underlying fundamentals of his processwere 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 broadcastwithout 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 kindof 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--almostall alterations of the original Indore system lessened its value--but Howard of 1941did not resist this dilutive trend because in an era of chemical farming any compostwas better than no compost, any return of humus better than none.
Still, I think it is useful to go backto the Indore research farm of the 1920s and to study closely how Albert Howard oncemade the world's finest compost, and to encounter this great man's thoughts beforehe 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 laterworks of Sir Albert Howard the reformer, Albert Howard the scientist and researcher,who wrote this book, is virtually unknown today.
At Indore, all available vegetablematerial was composted, including manure and bedding straw from the cattle shed,unconsumed crop residues, fallen leaves and other forest wastes, weeds, and greenmanures grown specifically for compost making. All of the urine from the cattle shed-inthe form of urine earth--and all wood ashes from any source on the farm were alsoincluded. 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 methodto work reliably the carbon to nitrogen ratio of the material going into the heapmust always be in the same range. Every time a heap was built the same assortmentof 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 calledthem "refractory"--must be thoroughly broken up before composting, otherwisethe fermentation would not be vigorous, rapid, and uniform throughout the process.This mechanical softening up was cleverly accomplished without power equipment byspreading tough crop wastes like cereal straw or pigeon pea and cotton stalks outover the farm roads, allowing cartwheels, the oxens' hooves, and foot traffic tobreak them up.
Decomposition must be rapid and aerobic,but not too aerobic. And not too hot. Quite intentionally, Indore compost piles werenot allowed to reach the highest temperatures that are possible. During the firstheating cycle, peak temperatures were about 140°. After two weeks, when thefirst turn was made, temperatures had dropped to about 125°, and gradually declinedfrom there. Howard cleverly restricted the air supply and thermal mass so as to "bankthe fires" of decomposition. This moderation was his key to preventing lossof nitrogen. Provisions were made to water the heaps as necessary, to turn them severaltimes, 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 therewas 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 intothe soil where nitrate nitrogen will be best preserved. But the soil is not capableof doing two jobs at once. It can't digest crude organic matter and simultaneouslynitrify humus. So compost must be finished and completely ripe when it was tilledin 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 thatflies must not be allowed to breed in the compost or around the work cattle. Countrylife 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 longby 14 feet wide by 2 feet deep with sloping sides. The pits were sufficiently spacedto allow loaded carts to have access to all sides of any of them and a system ofpipes brought water near every one. The materials to be composted were all storedadjacent to the factory. Howard's work oxen were conveniently housed in the nextbuilding.
Soil and Urine Earth
Howard had been raised on an Englishfarm and from childhood he had learned the ways of work animals and how to make themcomfortable. So, for the ease of their feet, the cattle shed and its attached, roofedloafing pen had earth floors. All soil removed from the silage pits, dusty sweepingsfrom the threshing floors, and silt from the irrigation ditches were stored nearthe cattle shed and used to absorb urine from the work cattle. This soil was spreadabout six inches deep in the cattle stalls and loafing pen. About three times a yearit was scraped up and replaced with fresh soil, the urine-saturated earth then wasdried and stored in a special covered enclosure to be used for making compost .
The presence of this soil in the heapwas essential. First, the black soil of Indore was well-supplied with calcium, magnesium,and other plant nutrients. These basic elements prevented the heaps from becomingoverly acid. Additionally, the clay in the soil was uniquely incorporated into theheap so that it coated everything. Clay has a strong ability to absorb ammonia, preventingnitrogen loss. A clay coating also holds moisture. Without soil, "an even andvigorous mycelial growth is never quickly obtained." Howard said "the fungiare the storm troops of the composting process, and must be furnished with all thearmament they need."
Crop wastes were protected from moisture,stored dry under cover near the compost factory. Green materials were first witheredin the sun for a few days before storage. Refractory materials were spread on thefarm's roads and crushed by foot traffic and cart wheels before stacking. All theseforms of vegetation were thinly layered as they were received so that the dry storagestacks became thoroughly mixed. Care was taken to preserve the mixing by cuttingvertical 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 compostheap made year-round was built with this complex assortment of vegetation havingthe same properties and the same C/N.
Special preliminary treatment was givento 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, andkept moist until they softened. Or they might be soaked in water for a few days andthen added to the bedding under the work cattle. Great care was taken when handlingthe cattle's bedding to insure that no flies would breed in it.
Though crop wastes and urine-earthcould 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 thatis essential to the rapid decomposition of cellulose and other dry vegetation. Withouttheir abundant presence composting would not begin as rapidly nor proceed as surely.
Charging the Compost Pits
Every effort was made to fill a pitto the brim within one week. If there wasn't enough material to fill an entire pitwithin one week, then a portion of one pit would be filled to the top. To preservegood aeration, every effort was made to avoid stepping on the material while fillingthe pit. As mixtures of manure and bedding were brought out from the cattle shedthey were thinly layered atop thin layers of mixed vegetation brought in from thedried reserves heaped up adjacent to the compost factory. Each layer was thoroughlywet down with a clay slurry made of three ingredients: water, urine-earth, and activelydecomposing material from an adjacent compost pit that had been filled about twoweeks earlier. This insured that every particle within the heap was moist and wascoated with nitrogen-rich soil and the microorganisms of decomposition. Today, wewould call this practice "mass inoculation."
Pits Versus Heaps
India has two primary seasons. Mostof 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 completelysaturated. Even though the pits were under a roof, they would fill with water duringthis period. So in the monsoon, compost was made in low heaps atop the ground. Comparedto the huge pits, their dimensions were smaller than you would expect: 7 x 7 feetat 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 itwas turned.
Howard was accomplishing several thingsby using shallow pits or low but very broad heaps. One, thermal masses were reducedso temperatures could not reach the ultimate extremes possible while composting.The pits were better than heaps because air flow was further reduced, slowing downthe fermentation, while their shallowness still permitted sufficient aeration. Therewere enough covered pits to start a new heap every week.
Temperature Range in
|Age in days ||Temperature in °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°-60° ||4 |
|60°-55° ||7 |
|55°-50° ||1 |
|50°-45° ||25 |
|45°-40° ||2 |
|40°-35° ||44 |
|35°-30° ||14 |
|97 days |
Turning the compost was donethree times: To insure uniform decomposition, to restore moisture and air, and tosupply massive quantities of those types of microbes needed to take the compostingprocess to its next stage.
The first turn was at about sixteendays. A second mass inoculation equivalent to a few wheelbarrows full of 30 day oldcomposting material was taken from an adjacent pit and spread thinly over the surfaceof the pit being turned. Then, one half of the pit was dug out with a manure forkand placed atop the first half. A small quantity of water was added, if needed tomaintain moisture. Now the compost occupied half the pit, a space about 15 x 14 andwas about three feet high, rising out of the earth about one foot. During the monsoonswhen heaps were used, the above-ground piles were also mass inoculated and then turnedso as to completely mix the material, and as we do today, placing the outside materialin the core and vice-versa.
One month after starting, or abouttwo weeks after the first turn, the pit or heap would be turned again. More waterwould be added. This time the entire mass would be forked from one half the pit tothe other and every effort would be made to fluff up the material while thoroughlymixing it. And a few loads of material were removed to inoculate a 15-day-old pit.
Another month would pass, or abouttwo months after starting, and for the third time the compost would be turned andthen allowed to ripen. This time the material is brought out of the pit and piledatop the earth so as to increase aeration. At this late stage there would be no dangerof 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 x10 at the base, 9 x 9 on top, and no more than 3-1/2 feet high. Again, more watermight be added. Ripening would take about one month. Howard's measurements showedthat after a month's maturation the finished compost should be used without delayor precious nitrogen would be lost. However, keep in mind when considering this briefripening period that the heap was already as potent as it could become. Howard'sproblem was not further improving the C/N, it was conservation of nitrogen.
The Superior Value of Indore Compost.
Howard said that finished Indore compostwas twice as rich in nitrogen as ordinary farmyard manure and that his target wascompost with a C/N of 10:1. Since it was long manure he was referring to, let's assumethat the C/N of a new heap started at 25:1.
The C/N of vegetation collected duringthe 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-canby using materials as they come available, then results will be highly erratic. Howardhad 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 experimentswere always unsatisfactory. So Howard wisely mixed his vegetation, first witheringand drying green materials by spreading them thinly in the sun to prevent their prematuredecomposition, and then taking great care to preserve a uniform mixture of vegetationtypes when charging his compost pits. This strategy can be duplicated by the homegardener. Howard was surprised to discover that he could compost all the crop wastehe had available with only half the urine earth and about one-quarter of the oxenmanure he had available. But fresh manure and urine earth were essential.
During the 1920s a patented processfor making compost with a chemical fertilizer called Adco was in vogue and Howardtried 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 enzymesand living bacteria that specialize in cellulose decomposition. Having a regularsupply of this material helped initiate decomposition without delay. Contributinglarge quantities of actively growing microorganisms through mass inoculation withmaterial from a two-week-old pile also helped. The second mass inoculation at twoweeks, with material from a month-old heap provided a large supply of the type oforganisms required when the heap began cooling. City gardeners without access tofresh manure may compensate for this lack by imitating Howard's mass inoculationtechnique, starting smaller amounts of compost in a series of bins and mixing intoeach bin a bit of material from the one further along at each turning. The passivebackyard composting container automatically duplicates this advantage. It simultaneouslycontains all decomposition stages and inoculates the material above by contact withmore decomposed material below. Using prepared inoculants in a continuous compostingbin is unnecessary.
City gardeners cannot readily obtainurine earth. Nor are American country gardeners with livestock likely to be willingto 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 throughcattle is discharged in the urine. But, equally important, soil itself was beneficialto the process. Of this Howard said, "[where] there may be insufficient dungand 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 artificialsare employed, it will be a great advantage to make use of soil." I am sure hewould 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 mostdifficult part of composting. First, the process must stay aerobic. That is one reasonthat single-material heaps fail because they tend to pack too tightly. To facilitateair exchange, the pits or heaps were never more than two feet deep. Where air wasinsufficient (though still aerobic) decay is retarded but worse, a process calleddenitrification occurs in which nitrates and ammonia are biologically broken downinto gasses and permanently lost. Too much manure and urine-earth can also interferewith aeration by making the heap too heavy, establishing anaerobic conditions. Thechart illustrates denitrification caused by insufficient aeration compared to turningthe 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
|4,500 ||4,514 |
|Total nitrogen (lb) at start ||31.25 ||29.12 |
|Total nitrogen at end ||29.49 ||32.36 |
|Loss or gain of nitrogen (lb) ||-1.76 ||+3.24 |
|Percentage loss or gain of nitrogen ||-6.1% ||+11.1% |
Finally, modern gardeners might reconsiderlimiting temperature during composting. India is a very warm climate with balmy nightsmost of the year. Heaps two or three feet high will achieve an initial temperatureof about 145°. The purchase of a thermometer with a long probe and a littleexperimentation will show you the dimensions that will more-or-less duplicate Howard'stemperature regimes in your climate with your materials.
Howard's technique of mass inoculationwith large amounts of biologically active material from older compost heaps speedsand directs decomposition. It supplies large numbers of the most useful types ofmicroorganisms so they dominate the heap's ecology before other less desirable typescan establish significant populations. I can't imagine how selling mass inoculantscould be turned into a business.
But just imagine that seeding a newheap with tiny amounts of superior microorganisms could speed initial decompositionand result in a much better product. That could be a business. Such an approachis not without precedent. Brewers, vintners, and bread makers all do that. And eversince composting became interesting to twentieth-century farmers and gardeners, entrepreneurshave been concocting compost starters that are intended to be added by the ounce(s)to the cubic yard.
Unlike the mass inoculation used atIndore, these inoculants are a tiny population compared to the microorganisms alreadypresent in any heap. In that respect, inoculating compost is very different thanbeer, wine, or bread. With these food products there are few or no microorganismsat the start. The inoculant, small as it might be, still introduces millions of timesmore desirable organisms than those wild types that might already be present.
But the materials being assembled intoa 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 likelyto introduce what is not present anyway. And the complex ecology of decompositionwill go through its inevitable changes as the microorganisms respond to variationsin temperature, aeration, pH, etc.
This is one area of controversy whereI am comfortable seeking the advice of an expert. In this case, the authority isClarence Golueke, who personally researched and developed U.C. fast composting inthe 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 ofcompost starters of all sorts because, in his business, entrepreneurs are constantlyattempting 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 testingstarters that eliminates any random effects and conclusively demonstrates their result.Inevitably, and repeatedly, he found that there was no difference between using astarter and not using one. And he says, "Although anecdotal accounts of successdue to the use of particular inoculum are not unusual in the popular media, we haveyet to come across unqualified accounts of successes in the refereed scientific andtechnical 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 ofcompost and soil from where the previous pile was made. Frankly, if I did not dothis I don't think the result would be any worse.
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