Organic Gardener's Composting Part 17

CHAPTER NINE

Making Superior Compost

The potency of composts can vary greatly. Most munic.i.p.al 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 cla.s.sified 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 gra.s.s, 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 pa.s.ses 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 quant.i.ty 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 quant.i.ty 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 gra.s.s or gra.s.s/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 gra.s.s 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 further compost.

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 take note.

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 marcier, who skillfully earned top returns growing out-of-season produce on intensive, double-dug raised beds, often under gla.s.s 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 quant.i.ties 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 r.e.t.a.r.d 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 cla.s.s 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 pa.s.sed 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 munic.i.p.al composting operation at Fallbrook, California makes clever use of this method to produce a smaller amount of high-grade product out of a larger quant.i.ty of low-grade ingredients. Mixtures of sewage sludge and munic.i.p.al 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 sc.r.a.ped off and used to form new vermicomposting beds. The castings below are considered finished compost. By laboratory a.n.a.lysis, the castings contain three or four times as much nitrogen as the crude compost being fed to the worms.

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 munic.i.p.ality 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 compost

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 bioma.s.s 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 a.s.serted 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.