List of Common Compost Ingredients
is a protein-rich perennial legume mainly grown as animal feed. On favorable soil it develops a deep root system, sometimes exceeding ten feet. Alfalfa draws heavily on subsoil minerals so it will be as rich or poor in nutrients as the subsoil it grew in. Its average C/N is around 12:1 making alfalfa useful to compensate for larger quantities of less potent material. Sacked alfalfa meal or pellets are usually less expensive (and being "stemmy," have a slightly higher C/N) than leafy, best-quality baled alfalfa hay. Rain-spoiled bales of alfalfa hay are worthless as animal feed but far from valueless to the composter.
Pelletized rabbit feed is largely alfalfa fortified with grain. Naturally, rabbit manure has a C/N very similar to alfalfa and is nutrient rich, especially if some provision is made to absorb the urine.
is wet and compact. If not well mixed with stiff, absorbent material, large clumps of this or other fruit wastes can become airless regions of anaerobic decomposition. Having a high water content can be looked upon as an advantage. Dry hay and sawdust can be hard to moisten thoroughly; these hydrate rapidly when mixed with fruit pulp. Fermenting fruit pulp attracts yellow jackets so it is sensible to incorporate it quickly into a pile and cover well with vegetation or soil.
The watery pulp of fruits is not particularly rich in nutrients but apple, grape, and pear pulps are generously endowed with soft, decomposable seeds. Most seeds contain large quantities of phosphorus, nitrogen, and other plant nutrients. It is generally true that plants locate much of their entire yearly nutrient assimilation into their seeds to provide the next generation with the best possible start. Animals fed on seeds (such as chickens) produce the richest manures.
Older books about composting warn about metallic pesticide residues adhering to fruit skins. However, it has been nearly half a century since arsenic and lead arsenate were used as pesticides and mercury is no longer used in fungicides.
is the voluminous waste product from extracting cane sugar. Its C/N is extremely high, similar to wheat straw or sawdust, and it contains very little in the way of plant nutrients. However, its coarse, strong, fibrous structure helps build lightness into a pile and improve air flow. Most sugar mills burn bagasse as their heat source to evaporate water out of the sugary juice squeezed from the canes. At one time there was far more bagasse produced than the mills needed to burn and bagasse often became an environmental pollutant. Then, bagasse was available for nothing or next to nothing. These days, larger, modern mills generate electricity with bagasse and sell their surplus to the local power grid. Bagasse is also used to make construction fiberboard for subwall and insulation.
and stalks are soft and lack strong fiber. They are moderately rich in phosphorus, potassium, and nitrogen. Consequently they rot quickly. Like other kitchen garbage, banana waste should be put into the core of a compost pile to avoid attracting and breeding flies. See also: Garbage.
is an industrial waste from smelting iron. Ore is refined by heating it with limestone and dolomite. The impurities combine with calcium and magnesium, rise to the surface of the molten metal, and are skimmed off. Basic slag contains quite a bit of calcium plus a variety of useful plant nutrients not usually found in limestone. Its exact composition varies greatly depending on the type of ore used.
Slag is pulverized and sold in sacks as a substitute for agricultural lime. The intense biological activity of a compost pile releases more of slag's other mineral content and converts its nutrients to organic substances that become rapidly available once the compost is incorporated into soil. Other forms of powdered mineralized rock can be similarly added to a compost pile to accelerate nutrient release.
Rodale Press, publisher of Organic Gardening
magazine is located in Pennsylvania where steel mills abound. Having more experience with slag, Rodale advises the user to be alert to the fact that some contain little in the way of useful nutrients and/or may contain excessive amounts of sulfur. Large quantities of sulfur can acidify soil. Read the analysis on the label. Agriculturally useful slag has an average composition of 40 percent calcium and 5 percent magnesium. It must also be very finely ground to be effective. See also: Lime
and Rock dust.
like bagasse, are a residue of extracting sugar. They have commercial value as livestock feed and are sold as dry pulp in feed stores located near regions where sugar beets are grown. Their C/N is in the vicinity of 20:1 and they may contain high levels of potassium, reaching as much as 4 percent.
Both spent hops (dried flowers and leaves) and malt (sprouted barley and often other grains) are potent nutrient sources with low C/N ratios. Spent malt is especially potent because brewers extract all the starches and convert them to sugar, but consider the proteins as waste because proteins in the brew make it cloudy and opaque. Hops may be easier to get. Malt has uses as animal feed and may be contracted for by some local feedlot or farmer. These materials will be wet, heavy and frutily odoriferous (though not unpleasantly so) and you will want to incorporate them into your compost pile immediately.
Buckwheat is a grain grown in the northeastern United States and Canada. Adapted to poor, droughty soils, the crop is often grown as a green manure. The seeds are enclosed in a thin-walled, brown to black fibrous hulls that are removed at a groat mill. Buckwheat hulls are light, springy, and airy. They'll help fluff up a compost heap. Buckwheat hulls are popular as a mulch because they adsorb moisture easily, look attractive, and stay in place. Their C/N is high. Oat and rice hulls are similar products.
See: Cottonseed meal.
is pulp left after castor oil has been squeezed from castor bean seeds. Like other oil seed residues it is very high in nitrogen, rich in other plant nutrients, particularly phosphorus, Castor pomace may be available in the deep South; it makes a fine substitute for animal manure.
may be available to gardeners living near industrial processors of orange, lemon, and grapefruit. In those regions, dried citrus pulp may also be available in feed stores. Dried orange skins contain about 3 percent phosphorus and 27 percent potassium. Lemons are a little higher in phosphorus but lower in potassium. Fruit culls would have a similar nutrient ratio on a dry weight basis, but they are largely water. Large quantities of culls could be useful to hydrate stubbornly dry materials like straw or sawdust.
Like other byproducts of industrial farming, citrus wastes may contain significant amounts of pesticide residues. The composting process will break down and eliminate most toxic organic residues, especially if the pile gets really hot through and through. (See also: _Leaves) _The effect of such high levels of potassium on the nutritional qualities of my food would also concern me if the compost I was making from these wastes were used for vegetable gardening.
are nutrient-rich like other seed meals. Even after brewing they can contain up to 2 percent nitrogen, about 1/2 percent phosphorus and varying amounts of potassium usually well below 1 percent. Its C/N runs around 12:1. Coffee roasters and packers need to dispose of coffee chaff, similar in nutrient value to used grounds and may occasionally have a load of overly roasted beans.
Coffee grounds seem the earthworm's food of choice. In worm bins,
used grounds are more vigorously devoured than any other substance.
If slight odor is a consideration, especially if doing in-the-home
vermicomposting, coffee grounds should be incorporated promptly into
a pile to avoid the souring that results from vinegar-producing
bacteria. Fermenting grounds may also attract harmless fruit flies.
Paper filters used to make drip coffee may be put into the heap or
worm box where they contribute to the bedding. See also: Paper.
are no longer available as an agricultural waste product because modern harvesting equipment shreds them and spits the residue right back into the field. However, home gardeners who fancy sweet corn may produce large quantities of cobs. Whole cobs will aerate compost heaps but are slow to decompose. If you want your pile ready within one year, it is better to dry and then grind the cobs before composting them.
is one of this country's major oil seed residues. The seed is ginned out of the cotton fiber, ground, and then its oil content is chemically extracted. The residue, sometimes called oil cake or seed cake, is very high in protein and rich in NPK. Its C/N runs around 5:1, making it an excellent way to balance a compost pile containing a lot of carboniferous materials.
Most cottonseed meal is used as animal feed, especially for beef and dairy cattle. Purchased in garden stores in small containers it is very expensive; bought by the 50-to 80-pound sack from feed stores or farm coops, cottonseed meal and other oil seed meals are quite inexpensive. Though prices of these types of commodities vary from year to year, oil cakes of all kinds usually cost between $200 to $400 per ton and only slightly higher purchased sacked in less-than-ton lots.
The price of any seed meal is strongly influenced by freight costs. Cottonseed meal is cheapest in the south and the southwest where cotton is widely grown. Soybean meal may be more available and priced better in the midwest. Canadian gardeners are discovering canola meal, a byproduct from producing canola (or rapeseed) oil. When I took a sabbatical in Fiji, I advised local gardeners to use coconut meal, an inexpensive "waste" from extracting coconut oil. And I would not be at all surprised to discover gardeners in South Dakota using sunflower meal. Sesame seed, safflower seed, peanut and oil-seed corn meals may also be available in certain localities.
Seed meals make an ideal starting point for compounding complete organic fertilizer mixes. The average NPK analysis of most seed meals is around 6-4-2. Considered as a fertilizer, oil cakes are somewhat lacking in phosphorus and sometimes in trace minerals. By supplementing them with materials like bone meal, phosphate rock, kelp meal, sometimes potassium-rich rock dusts and lime or gypsum, a single, wide-spectrum slow-release trace-mineral-rich organic fertilizer source can be blended at home having an analysis of about 5-5-5. Cottonseed meal is particularly excellent for this purpose because it is a dry, flowing, odorless material that stores well. I suspect that cottonseed meal from the southwest may be better endowed with trace minerals than that from leached-out southeastern soils or soy meal from depleted midwestern farms. See the last section of Chapter Eight.
Some organic certification bureaucracies foolishly prohibit or discourage the use of cottonseed meal as a fertilizer. The rationale behind this rigid self-righteousness is that cotton, being a nonfood crop, is sprayed with heavy applications of pesticides and/or herbicides that are so hazardous that they not permitted on food crops. These chemicals are usually dissolved in an emulsified oil-based carrier and the cotton plant naturally concentrates pesticide residues and breakdown products into the oily seed.
I believe that this concern is accurate as far as pesticide residues being translocated into the seed. However, the chemical process used to extract cottonseed oil is very efficient The ground seeds are mixed with a volatile solvent similar to ether and heated under pressure in giant retorts. I reason that when the solvent is squeezed from the seed, it takes with it all not only the oil, but, I believe, virtually all of the pesticide residues. Besides, any remaining organic toxins will be further destroyed by the biological activity of the soil and especially by the intense heat of a compost pile.
What I personally
worry about is cottonseed oil. I avoid prepared salad dressings that may contain cottonseed oil, as well as many types of corn and potato chips, tinned oysters, and other prepared food products. I also suggest that you peek into the back of your favorite Oriental and fast food restaurants and see if there aren't stacks of ten gallon cottonseed oil cans waiting to fill the deep-fat fryer. I fear this sort of meal as dangerous to my health. If you still fear that cottonseed meal is also a dangerous product then you certainly won't want to be eating feedlot beef or drinking milk or using other dairy products from cattle fed on cottonseed meal.
runs 10-12 percent nitrogen and contains significant amounts of phosphorus. It is the only organic fertilizer that is naturally water soluble. Blood meal, like other slaughterhouse wastes, may be too expensive for use as a compost activator.
Sprinkled atop soil as a side-dressing, dried blood usually provokes a powerful and immediate growth response. Blood meal is so potent that it is capable of burning plants; when applied you must avoid getting it on leaves or stems. Although principally a source of nitrogen, I reason that there are other nutritional substances like growth hormones or complex organic "phytamins" in blood meal. British glasshouse lettuce growers widely agree that lettuce sidedressed with blood meal about three weeks before harvest has a better "finish," a much longer shelf-life, and a reduced tendency to "brown butt" compared to lettuce similarly fertilized with urea or chemical nitrate sources.
are the birds' equivalent of hair on animals and have similar properties. See Hair
Fish and shellfish waste.
These proteinaceous, high-nitrogen and trace-mineral-rich materials are readily available at little or no cost in pickup load lots from canneries and sea food processors. However, in compost piles, large quantities of these materials readily putrefy, make the pile go anaerobic, emit horrid odors, and worse, attract vermin and flies. To avoid these problems, fresh seafood wastes must be immediately mixed with large quantities of dry, high C/N material. There probably are only a few homestead composters able to utilize a ton or two of wet fish waste at one time.
Oregonians pride themselves for being tolerant, slow-to-take-offense neighbors. Along the Oregon coast, small-scale market gardeners will thinly spread shrimp or crab waste atop a field and promptly till it in. Once incorporated in the soil, the odor rapidly dissipates. In less than one week.
is a much better alternative for use around the home. Of course, you have to have no concern for cost and have your mind fixed only on using the finest possible materials to produce the nutritionally finest food when electing to substitute fish meal for animal manures or oil cakes. Fish meal is much more potent than cottonseed meal. Its typical nutrient analysis runs 9-6-4. However, figured per pound of nutrients they contain, seed meals are a much less expensive way to buy NPK. Fish meal is also mildly odoriferous. The smell is nothing like wet seafood waste, but it can attract cats, dogs, and vermin.
What may make fish meal worth the trouble and expense is that sea
water is the ultimate depository of all water-soluble nutrients that
were once in the soil. Animals and plants living in the sea enjoy
complete, balanced nutrition. Weston Price's classic book,
Nutrition and Physical Degeneration,
attributes nearly perfect health to humans who made seafoods a significant portion of their diets. Back in the 1930sâ€”before processed foods were universally available in the most remote locations-people living on isolated sea coasts tended to live long, have magnificent health, and perfect teeth. See also: Kelp meal.
Most forms of kitchen waste make excellent compost. But Americans foolishly send megatons of kitchen garbage to landfills or overburden sewage treatment plants by grinding garbage in a disposal. The average C/N of garbage is rather low so its presence in a compost heap facilitates the decomposition of less potent materials. Kitchen garbage can also be recycled in other ways such as vermicomposting (worm boxes) and burying it in the garden in trenches or post holes. These alternative composting methods will be discussed in some detail later.
Putting food scraps and wastes down a disposal is obviously the least troublesome and apparently the most "sanitary" method, passing the problem on to others. Handled with a little forethought, composting home food waste will not breed flies or make the kitchen untidy or ill smelling. The most important single step in keeping the kitchen clean and free of odor is to put wastes in a small plastic bucket or other container of one to two gallons in size, and empty it every few days. Periodically adding a thin layer of sawdust or peat moss supposedly helps to prevent smells. In our kitchen, we've found that covering the compost bucket is no alternative to emptying it. When incorporating kitchen wastes into a compost pile, spread them thinly and cover with an inch or two of leaves, dry grass, or hay to adsorb wetness and prevent access by flies. It may be advisable to use a vermin-tight composting bin.
See Rock dust.
See Apple pomace.
Along with kitchen garbage, grass clippings are the compostable material most available to the average homeowner. Even if you (wisely) don't compost all of your clippings (see sidebar), your foolish neighbors may bag theirs up for you to take away. If you mulch with grass clippings, make sure the neighbors aren't using "weed and feed" type fertilizers, or the clippings may cause the plants that are mulched to die. Traces of the those types of broadleaf herbicides allowed in "weed and feed" fertilizers, are thoroughly decomposed in the composting process.
It is not necessary to return every bit of organic matter to maintain a healthy lawn. Perhaps one-third to one-half the annual biomass production may be taken away and used for composting without seriously depleting the lawn's vigor, especially if one application of a quality fertilizer is given to the lawn each year. Probably the best time of year to remove clippings is during the spring while the grass is growing most rapidly. Once a clover/grass mix is established it is less necessary to use nitrogen fertilizers. In fact, high levels of soil nitrates reduces the clover's ability to fix atmospheric nitrogen. However, additions of other mineral nutrients like phosphorus, potassium, and especially calcium may still be necessary.
Lawn health is similar to garden health. Both depend on the presence of large enough quantities of organic material in the soil. This organic matter holds a massive reserve of nutrition built up over the years by the growing plants themselves. When, for reasons of momentary aesthetics, we bag up and remove clippings from our lawn, we prevent the grass from recycling its own fertility.
It was once mistakenly believed that unraked lawn clippings built up on the ground as unrotted thatch, promoting harmful insects and diseases. This is a half-truth. Lawns repeatedly fertilized with sulfur-based chemical fertilizers, especially ammonium sulfate and superphosphate, become so acid and thus so hostile to bacterial decomposition and soil animals that a thatch of unrotted clippings and dead sod can build up and thus promote disease and insect problems.
However, lawns given lime or gypsum to supply calcium that is so vital to the healthy growth of clover, and seed meals and/or dressings of finely decomposed compost or manure become naturally healthy. Clippings falling on such a lawn rot rapidly because of the high level of microorganisms in the soil, and disappear in days. Dwarf white clover can produce all the nitrate nitrogen that grasses need to stay green and grow lustily. Once this state of health is developed, broadleaf weeds have a hard time competing with the lusty grass/clover sod and gradually disappear. Fertilizing will rarely be necessary again if little biomass is removed.
Homeowners who demand the spiffy appearance of a raked lawn but still want a healthy lawn have several options. They may compost their grass clippings and then return the compost to the lawn. They may use a side-discharge mower and cut two days in succession. The first cut will leave rows of clippings to dry on the lawn; the second cut will disintegrate those clippings and pretty much make them disappear. Finally, there are "mulching" mowers with blades that chop green grass clippings into tiny pieces and drops them below the mower where they are unnoticeable.
Grass clippings, especially spring grass, are very high in nitrogen, similar to the best horse or cow manure. Anyone who has piled up fresh grass clippings has noticed how rapidly they heat up, how quickly the pile turns into a slimy, airless, foul-smelling anaerobic mess, and how much ammonia may be given off. Green grass should be thoroughly dispersed into a pile, with plenty of dry material. Reserve bags of leaves from the fall or have a bale of straw handy to mix in if needed. Clippings allowed to sun dry for a few days before raking or bagging behave much better in the compost heap.
See Rock dust.
contains ten times the nitrogen of most manures. It resists absorbing moisture and readily compresses, mats, and sheds water, so hair needs to be mixed with other wetter materials. If I had easy access to a barber shop, beauty salon, or poodle grooming business, I'd definitely use hair in my compost. Feathers, feather meal and feather dust (a bird's equivalent to hair) have similar qualities.
In temperate climates, pasture grasses go through an annual cycle that greatly changes their nutrient content. Lawn grasses are not very different. The first cuttings of spring grass are potent sources of nitrogen, high in protein and other vital mineral nutrients. In fact, spring grass may be as good an animal feed as alfalfa or other legume hay. Young ryegrass, for example, may exceed two percent nitrogen-equaling about 13 percent protein. That's why cattle and horses on fresh spring grass frisk around and why June butter is so dark yellow, vitamin-rich and good-flavored.
In late spring, grasses begin to form seed and their chemical composition changes. With the emergence of the seed stalk, nitrogen content drops markedly and the leaves become more fibrous, ligninous, and consequently, more reluctant to decompose. At pollination ryegrass has dropped to about l percent nitrogen and by the time mature seed has developed, to about 0.75 percent.
These realities have profound implications for hay-making, for using grasses as green manures, and for evaluating the C/N of hay you may be planning to use in a compost heap. In earlier times, making grass hay that would be nutritious enough to maintain the health of cattle required cutting the grass before, or just at, the first appearance of seed stalks. Not only did early harvesting greatly reduce the bulk yield, it usually meant that without concern for cost or hours of labor the grass had to be painstakingly dried at a time of year when there were more frequent rains and lower temperatures. In nineteenth-century England, drying grass was draped by hand over low hurdles, dotting each pasture with hundreds of small racks that shed water like thatched roofs and allowed air flow from below. It is obvious to me where the sport of running hurdles came from; I envision energetic young countryfolk, pepped up on that rich spring milk and the first garden greens of the year, exuberantly racing each other across the just-mowed fields during haying season.
In more recent years, fresh wet spring grass was packed green into pits and made into silage where a controlled anaerobic fermentation retained its nutritional content much like sauerkraut keeps cabbage. Silage makes drying unnecessary. These days, farm labor is expensive and tractors are relatively inexpensive. It seems that grass hay must be cut later when the weather is more stable, economically dried on the ground, prevented from molding by frequent raking, and then baled mechanically.
In regions enjoying relatively rainless springs or where agriculture depends on irrigation, this system may result in quality hay. But most modern farmers must supplement the low-quality hay with oil cakes or other concentrates. Where I live, springs are cool and damp and the weather may not stabilize until mid-June. By this date grass seed is already formed and beginning to dry down. This means our local grass hay is very low in protein, has a high C/N, and is very woody, little better than wheat straw. Pity the poor horses and cattle that must try to extract enough nutrition from this stuff.
Western Oregon weather conditions also mean that farmers often end up with rain-spoiled hay they are happy to sell cheaply. Many years I've made huge compost piles largely from this kind of hay. One serious liability from cutting grass hay late is that it will contain viable seeds. If the composting process does not thoroughly heat all of these seeds, the compost will sprout grass all over the garden. One last difficulty with poor quality grass hay: the tough, woody stems are reluctant to absorb moisture.
The best way to simultaneously overcome all of these liabilities is first to permit the bales to thoroughly spoil and become moldy through and through before composting them. When I have a ton or two of spoiled hay bales around, I spread them out on the ground in a single layer and leave them in the rain for an entire winter. Doing this sprouts most of the grass seed within the bales, thoroughly moistens the hay, and initiates decomposition. Next summer I pick up this material, remove the baling twine, and mix it into compost piles with plenty of more nitrogenous stuff.
One last word about grass and how it works when green manuring. If a thick stand of grasses is tilled in during spring before seed formation begins, its high nitrogen content encourages rapid decomposition. Material containing 2 percent nitrogen and lacking a lot of tough fiber can be totally rotted and out of the way in two weeks, leaving the soil ready to plant. This variation on green manuring works like a charm.
However, if unsettled weather conditions prevent tillage until seed formation has begun, the grasses will contain much less nitrogen and will have developed a higher content of resistant lignins. If the soil does not become dry and large reserves of nitrogen are already waiting in the soil to balance the high C/N of mature grass, it may take only a month to decompose But there will be so much decomposition going on for the first few weeks that even seed germination is inhibited. Having to wait an unexpected month or six weeks after wet weather prevented forming an early seed bed may delay sowing for so long that the season is missed for the entire year. Obstacles like this must be kept in mind when considering using green manuring as a soil-building technique. Cutting the grass close to the soil line and composting the vegetation off the field eliminates this problem.
Hoof and horn meal.
Did you know that animals construct their hooves and horns from compressed hair? The meal is similar in nutrient composition to blood meal, leather dust, feather meal, or meat meal (tankage). It is a powerful source of nitrogen with significant amounts of phosphorus. Like other slaughterhouse byproducts its high cost may make it impractical to use to adjust the C/N of compost piles. Seed meals or chicken manure (chickens are mainly fed seeds) have somewhat lower nitrogen contents than animal byproducts but their price per pound of actual nutrition is more reasonable. If hoof and horn meal is not dispersed through a pile it may draw flies and putrefy. I would prefer to use expensive slaughterhouse concentrates to blend into organic fertilizer mixes.
See Apple pomace.
from several countries are available in feed and grain stores and better garden centers, usually in 25 kg (55-pound) sacks ranging in cost from $20 to $50. Considering this spendy price, I consider using kelp meal more justifiable in complete organic fertilizer mixes as a source of trace minerals than as a composting supplement.
There is a great deal of garden lore about kelp meal's growth-stimulating and stress-fortifying properties. Some garden-store brands tout these qualities and charge a very high price. The best prices are found at feed dealers where kelp meal is considered a bulk commodity useful as an animal food supplement.
I've purchased kelp meal from Norway, Korea, and Canada. There are probably other types from other places. I don't think there is a significant difference in the mineral content of one source compared to another. I do not deny that there may be differences in how well the packers processing method preserved kelp's multitude of beneficial complex organic chemicals that improve the growth and overall health of plants by functioning as growth stimulants, phytamins, and who knows what else.
Still, I prefer to buy by price, not by mystique, because, after
gardening for over twenty years, garden writing for fifteen and
being in the mail order garden seed business for seven I have been
on the receiving end of countless amazing claims by touters of
agricultural snake oils; after testing out dozens of such
concoctions I tend to disbelieve mystic contentions of unique
superiority. See also: Seaweed
is a waste product of tanneries, similar to hoof and horn meal or tankage. It may or may not be contaminated with high levels of chromium, a substance used to tan suede. If only vegetable-tanned leather is produced at the tannery in question, leather dust should be a fine soil amendment. Some organic certification bureaucrats prohibit its use, perhaps rightly so in this case.
Soil nutrients are dissolved by rain and leached from surface layers, transported to the subsoil, thence the ground water, and ultimately into the salty sea. Trees have deep root systems, reaching far into the subsoil to bring plant nutrients back up, making them nature's nutrient recycler. Because they greatly increase soil fertility, J. Russell Smith called trees "great engines of production." Anyone who has not read his visionary book, Tree Crops,
should. Though written in 1929, this classic book is currently in print.
Once each year, leaves are available in large quantity, but aren't the easiest material to compost. Rich in minerals but low in nitrogen, they are generally slow to decompose and tend to pack into an airless mass. However, if mixed with manure or other high-nitrogen amendment and enough firm material to prevent compaction, leaves rot as well as any other substance. Running dry leaves through a shredder or grinding them with a lawnmower greatly accelerates their decomposition. Of all the materials I've ever put through a garden grinder, dry leaves are the easiest and run the fastest.
Once chopped, leaves occupy much less volume. My neighbor, John, a very serious gardener like me, keeps several large garbage cans filled with pulverized dry leaves for use as mulch when needed. Were I a northern gardener I'd store shredded dry leaves in plastic bags over the winter to mix into compost piles when spring grass clippings and other more potent materials were available. Some people fear using urban leaves because they may contain automotive pollutants such as oil and rubber components. Such worries are probably groundless. Dave Campbell who ran the City of Portland (Oregon) Bureau of Maintenance leaf composting program said he has run tests for heavy metals and pesticide residues on every windrow of compost he has made.
"Almost all our tests so far have shown less than the background level for heavy metals, and no traces of pesticides [including] chlorinated and organophosphated pesticidesâ€¦. It is very rare for there to be any problem."
Campbell tells an interesting story that points out how thoroughly composting eliminates pesticide residues. He said,
"Once I was curious about some leaves we were getting from a city park where I knew the trees had been sprayed with a pesticide just about a month before the leaves fell and we collected them. In this case, I had the uncomposted leaves tested and then the compost tested. In the fresh leaves a trace of . . . residue was detected, but by the time the composting process was finished, no detectable level was found."
There is no disputing that calcium is a vital soil nutrient as essential to the formation of plant and animal proteins as nitrogen. Soils deficient in calcium can be inexpensively improved by adding agricultural lime which is relatively pure calcium carbonate (CaC03). The use of agricultural lime or dolomitic lime in compost piles is somewhat controversial. Even the most authoritative of authorities disagree. There is no disputing that the calcium content of plant material and animal manure resulting from that plant material is very dependent on the amount of calcium available in the soil. Chapter Eight contains quite a thorough discussion of this very phenomena. If a compost pile is made from a variety of materials grown on soils that contained adequate calcium, then adding additional lime should be unnecessary. However, if the materials being composted are themselves deficient in calcium then the organisms of decomposition may not develop fully.
While preparing this book, I queried the venerable Dr. Herbert H. Koepf about lime in the compost heap. Koepf's biodynamic books served as my own introduction to gardening in the early 1970s. He is still active though in his late seventies. Koepf believes that lime is not necessary when composting mixtures that contain significant amounts of manure because the decomposition of proteinaceous materials develops a more or less neutral pH. However, when composting mixtures of vegetation without manure, the conditions tend to become very acid and bacterial fermentation is inhibited. To correct low pH, Koepf recommends agricultural lime at 25 pounds per ton of vegetation, the weight figured on a dry matter basis. To guestimate dry weight, remember that green vegetation is 70-80 percent water, to prevent organic material like hay from spoiling it is first dried down to below 15 percent moisture.
There is another reason to make sure that a compost pile contains an abundance of calcium. Azobacteria, that can fix nitrate nitrogen in mellowing compost piles, depend for their activity on the availability of calcium. Adding agricultural lime in such a situation may be very useful, greatly speed the decomposition process, and improve the quality of the compost. Albert Howard used small amounts of lime in his compost piles specifically to aid nitrogen fixation. He also incorporated significant quantities of fresh bovine manure at the same time.
However, adding lime to heating manure piles results in the loss of large quantities of ammonia gas. Perhaps this is the reason some people are opposed to using lime in any composting process. Keep in mind that a manure pile is not a compost pile. Although both will heat up and decay, the starting C/N of a barnyard manure pile runs around 10:1 while a compost heap of yard waste and kitchen garbage runs 25:1 to 30:1. Any time highly nitrogenous material, such as fresh manures or spring grass clippings, are permitted to decompose without adjustment of the carbon-to-nitrogen ratio with less potent stuff, ammonia tends to be released, lime or not.
Only agricultural lime or slightly better, dolomitic lime, are useful in compost piles. Quicklime or slaked lime are made from heated limestone and undergo a violent chemical reaction when mixed with water. They may be fine for making cement, but not for most agricultural purposes.
See Cottonseed meal
Fresh manure can be the single most useful addition to the compost pile. What makes it special is the presence of large quantities of active digestive enzymes. These enzymes seem to contribute to more rapid heating and result in a finer-textured, more completely decomposed compost that provokes a greater growth response in plants. Manure from cattle and other multi-stomached ruminants also contains cellulose-decomposing bacteria. Soil animals supply similar digestive enzymes as they work over the litter on the forest floor but before insects and other tiny animals can eat much of a compost heap, well-made piles will heat up, driving out or killing everything except microorganisms and fungi.
All of the above might be of interest to the country dweller or serious backyard food grower but probably sounds highly impractical to most of this book's readers. Don't despair if fresh manure is not available or if using it is unappealing. Compost made with fresh, unheated manure works only a little faster and produces just a slightly better product than compost activated with seed meals, slaughterhouse concentrates, ground alfalfa, grass clippings, kitchen garbage, or even dried, sacked manures. Compost made without any manure still "makes!"
When evaluating manure keep in mind the many pitfalls. Fresh manure is very valuable, but if you obtain some that has been has been heaped up and permitted to heat up, much of its nitrogen may already have dissipated as ammonia while the valuable digestive enzymes will have been destroyed by the high temperatures at the heap's core. A similar degradation happens to digestive enzymes when manure is dried and sacked. Usually, dried manure comes from feedlots where it has also first been stacked wet and gone through a violent heating process. So if I were going to use sacked dried manure to lower the C/N of a compost pile, I'd evaluate it strictly on its cost per pound of actual nitrogen. In some cases, seed meals might be cheaper and better able to drop the heap's carbon-to-nitrogen ratio even more than manure.
There are many kinds of manure and various samples of the same type of manure may not be equal. This demonstrates the principle of what goes in comes out. Plants concentrate proteins and mineral nutrients in their seed so animals fed on seed (like chickens) excrete manure nearly as high in minerals and with a C/N like seed meals (around 8:1). Alfalfa hay is a legume with a C/N around 12:1. Rabbits fed almost exclusively on alfalfa pellets make a rich manure with a similar C/N. Spring grass and high quality hay and other leafy greens have a C/N nearly as good as alfalfa. Livestock fed the best hay supplemented with grain and silage make fairly rich manure. Pity the unfortunate livestock trying to survive as "strawburners" eating overly mature grass hay from depleted fields. Their manure will be as poor as the food and soil they are trying to live on.
When evaluating manure, also consider the nature and quantity of bedding mixed into it. Our local boarding stables keep their lazy horses on fir sawdust. The idle "riding" horses are usually fed very strawy local grass hay with just enough supplemental alfalfa and grain to maintain a minimal healthy condition. The "horse manure" I've hauled from these stables seems more sawdust than manure. It must have a C/N of 50 or 60:1 because by itself it will barely heat up.
Manure mixed with straw is usually richer stuff. Often this type comes from dairies. Modern breeds of milk cows must be fed seed meals and other concentrates to temporarily sustain them against depletion from unnaturally high milk production.
After rabbit and chicken, horse manure from well-fed animals like race horses or true, working animals may come next. Certainly it is right up there with the best cow manure. Before the era of chemical fertilizer, market gardeners on the outskirts of large cities took wagon loads of produce to market and returned with an equivalent weight of "street sweepings." What they most prized was called "short manure," or horse manure without any bedding. Manure and bedding mixtures were referred to as "long manure" and weren't considered nearly as valuable.
Finally, remember that over half the excretion of animals is urine. And far too little value is placed on urine. As early as 1900 it was well known that if you fed one ton (dry weight) of hay and measured the resulting manure after thorough drying, only 800 pounds was left. What happened to the other 1,200 pounds of dry material? Some, of course, went to grow the animal. Some was enzymatically "burned" as energy fuel and its wastes given off as CO2 and H2O. Most of it was excreted in liquid form. After all, what is digestion but an enzymatic conversion of dry material into a water solution so it can be circulated through the bloodstream to be used and discarded as needed. Urine also contains numerous complex organic substances and cellular breakdown products that improve the health of the soil ecology.
However, urine is not easy to capture. It tends to leach into the ground or run off when it should be absorbed into bedding. Chicken manure and the excrements of other fowl are particularly valuable in this respect because the liquids and solids of their waste are uniformly mixed so nothing is lost. When Howard worked out his system of making superior compost at Indore, he took full measure of the value of urine and paid great care to its capture and use.
is almost pure cellulose and has a very high C/N like straw or sawdust. It can be considered a valuable source of bulk for composting if you're using compost as mulch. Looked upon another way, composting can be a practical way to recycle paper at home.
The key to composting paper is to shred or grind it. Layers of paper will compress into airless mats. Motor-driven hammermill shredders will make short work of dry paper. Once torn into tiny pieces and mixed with other materials, paper is no more subject to compaction than grass clippings. Even without power shredding equipment, newsprint can be shredded by hand, easily ripped into narrow strips by tearing whole sections along the grain of the paper, not fighting against it.
Evaluating Nitrogen Content
A one-cubic foot bag of dried steer manure weighs 25 pounds and is labeled 1 percent nitrogen. That means four sacks weighs 100 pounds and contains 1 pound of actual nitrogen.
A fifty pound bag of cottonseed meal contains six percent nitrogen. Two sacks weighs 100 pounds and contains 6 pounds of actual nitrogen.
Therefore it takes 24 sacks of steer manure to equal the nitrogen contained in two sacks of cottonseed meal.
If steer manure costs $1.50 per sack, six pound of actual nitrogen from steer manure costs 24 x $1.50 = $36.00
If fifty pounds of cottonseed meal costs $7.50, then six pounds of actual nitrogen from cottonseed meal costs 2 x $7.50 = $15.00.
Now, lets take a brief moment to see why industrial farmers thinking only of immediate financial profit, use chemical fertilizers. Urea, a synthetic form of urine used as nitrogen fertilizer contains 48 percent nitrogen. So 100 pounds of urea contains 48 pounds of nitrogen. That quantity of urea also costs about $15.00!
Without taking into account its value in terms of phosphorus, potassium and other mineral contents, nitrogen from seed meal costs at least eight times as much per pound as nitrogen from urea.
Newspapers, even with colored inks, can be safely used in compost piles. Though some colored inks do contain heavy metals, these are not used on newsprint.
However, before beginning to incorporate newsprint into your composting, reconsider the analyses of various types of compost broken out as a table in the previous chapter. The main reason many municipal composting programs make a low-grade product with such a high C/N is the large proportion of paper used. If your compost is intended for use as mulch around perennial beds or to be screened and broadcast atop lawns, then having a nitrogen-poor product is of little consequence. But if your compost is headed for the vegetable garden or will be used to grow the largest possible prized flowers then perhaps newsprint could be recycled in another way.
, especially corrugated material, is superior to newsprint for compost making because its biodegradable glues contain significant amounts of nitrogen. Worms love to consume cardboard mulch. Like other forms of paper, cardboard should be shredded, ground or chopped as finely as possible, and thoroughly mixed with other materials when composted._
, may contain disease organisms that infect humans. Though municipal composting systems can safely eliminate such diseases, home composting of dog and cat manure may be risky if the compost is intended for food gardening.
If your garden soil is deficient in phosphorus, adding rock phosphate to the compost pile may accelerate its availability in the garden, far more effectively than adding phosphate to soil. If the vegetation in your vicinity comes from soils similarly deficient in phosphorus, adding phosphate rock will support a healthier decomposition ecology and improve the quality of your compost. Five to ten pounds of rock phosphate added to a cubic yard of uncomposted organic matter is about the right amount.
See Buckwheat hulls.
All plant nutrients except nitrogen originally come from decomposing rock. Not all rocks contain equal concentrations and assortments of the elements plants use for nutrients. Consequently, not all soils lustily grow healthy plants. One very natural way to improve the over all fertility of soil is to spread and till in finely ground rock flour make from highly mineralized rocks.
This method is not a new idea. Limestone and dolomite, soft, easily powdered rocks, have been used for centuries to add calcium and magnesium. For over a century, rock phosphate and kainite, a soft, readily soluble naturally occurring rock rich in potassium, magnesium and sulfur, have been ground and used as fertilizer. Other natural rock sources like Jersey greensand have long been used in the eastern United States on some unusual potassium-deficient soils.
Lately it has become fashionable to remineralize the earth with heavy applications of rock flours. Unlike most fads and trends, this one is wise and should endure. The best rocks to use are finely ground "basic" igneous rocks like basalts. They are called basic as opposed to "acid" rocks because they are richer in calcium and magnesium with lesser quantities of potassium. When soil forms from these materials it tends to not be acid. Most basic igneous rocks also contain a wide range of trace mineral nutrients. I have observed marked improvements in plant growth by incorporating ordinary basalt dust that I personally shoveled from below a conveyor belt roller at a local quarry where crushed rock was being prepared for road building. Basalt dust was an unintentional byproduct.
Though highly mineralized rock dust may be a valuable soil amendment, its value must equal its cost. Application rates of one or two tons per acre are minimal. John Hamaker's _The Survival of Civilization _suggests eight to ten tons per acre the first application and then one or two tons every few years thereafter. This means the correct price for rock dust is similar to the price for agricultural lime; in my region that's about $60 to $80 a ton in sacks. Local farmers pay about $40 a ton in bulk, including spreading on your field by the seller. A fifty-pound sack of rock dust should retail for about $2. These days it probably costs several times that price, tending to keep rock dust a novelty item.
The activities of fungi and bacteria are the most potent forces making nutrients available to plants. As useful as tilling rock powders into soil may be, the intense biological activity of the compost pile accelerates their availability. And the presence of these minerals might well make a compost pile containing nutrient-deficient vegetation work faster and become better fertilizer. Were the right types of rock dust available and cheap, I'd make it about 5 percent by volume of my heap, and equal that with rich soil.
See Cottonseed meal.
contains virtually nothing but carbon. In small quantities it is useful to fluff up compost piles and prevent compaction. However this is only true of coarse material like that from sawmills or chain saws. The fine saw dust from carpentry and cabinet work may compact and become airless. See _Paper _for a discussion of lowering the fertilizing value of compost with high C/N materials.
when freshly gathered is an extraordinary material for the compost pile. Like most living things from the ocean seaweeds are rich in all of the trace minerals and contain significant amounts of the major nutrients, especially potassium, with lesser amounts of phosphorus and nitrogen. Seaweeds enrich the heap, decompose very rapidly, and assist other materials to break down. Though heavy and often awkward to gather and haul, if they are available, seaweeds should not be permitted to go to waste.
Those with unlimited money may use sprinklings of kelp meal in the compost pile to get a similar effect. However, kelp meal may be more economically used as part of a complete organic fertilizer mixture that is worked into soil.
Shrub and tree
prunings are difficult materials to compost unless you have a shredder/chipper. Even after being incorporated into one hot compost heap after another, half-inch diameter twigs may take several years to fully decompose. And turning a heap containing long branches can be very difficult. But buying power equipment just to grind a few cart loads of hedge and tree prunings each year may not be economical. My suggestion is to neatly tie any stick larger than your little finger into tight bundles about one foot in diameter and about 16 inches long and then burn these "faggots" in the fireplace or wood stove. This will be less work in the long run.
Soil is an often overlooked but critically important part of the compost pile. Least of its numerous benefits, soil contains infinitudes of microorganisms that help start out decomposition. Many compostable materials come with bits of soil already attached and few are sterile in themselves. But extra soil ensures that there will initially be a sufficient number and variety of these valuable organisms. Soil also contains insoluble minerals that are made soluble by biological activity. Some of these minerals may be in short supply in the organic matter itself and their addition may improve the health and vigor of the whole decomposition ecology. A generous addition of rock dust may do this even better.
Most important, soil contains nitrification microorganisms that readily convert ammonia gas to nitrates, and clay that will catch and temporarily hold ammonia. Nitrifying bacteria do not live outside of soil. Finally, a several inch thick layer of soil capping the heap serves as an extra insulator, holding in heat, raising the core temperature and helping seal in moisture. Making a compost heap as much as 10 percent soil by dry weight is the right target
Try thinking of soil somewhat like the moderators in an atomic reactor, controlling the reaction by trapping neutrons. Soil won't change the C/N of a heap but not being subject to significant breakdown it will slightly lower the maximum temperature of decomposition; while trapping ammonia emissions; and creating better conditions for nitrogen fixing bacteria to improve the C/N as the heap cools and ripens.
See Cottonseed meal.
is a carboniferous material similar to sawdust but usually contains more nutrients. It is a valuable aerator, each stalk acting as a tube for air to enter and move through the pile. Large quantities of long straw can make it very difficult to turn a heap the first time. I'd much prefer to have manure mixed with straw than with sawdust.
See Cottonseed meal.
is another slaughterhouse or rendering plant waste consisting of all animal refuse except blood and fat. Locally it is called meat meal. See Hoof and horn meal.
Tofu factory waste.
Okara is the pulp left after soy milk has been squeezed from cooked, ground soybeans. Small-scale tofu makers will have many gallons of okara to dispose of each day. It makes good pig food so there may be competition to obtain it. Like any other seed waste, okara is high in nitrogen and will be wet and readily putrefiable like brewery waste. Mix into compost piles immediately.
Their nutrient content is highly variable depending on the species and age of the plant. Weeds gone to seed are both low in nitrogen and require locating in the center of a hot heap to kill off the seeds. Tender young weeds are as rich in nitrogen as spring grass.
Weeds that propagate through underground stems or rhizomes like quack-grass, Johnsongrass, bittersweet, and the like are better burnt.
from hardwoods is rich in potassium and contains significant amounts of calcium and other minerals. Ash from conifers may be similarly rich in potassium but contains little else. Wood ashes spread on the ground tend to lose their nutrients rapidly through leaching. If these nutrients are needed in your soil, then add the ash to your compost piles where it will become an unreachable part of the biomass that will be gradually released in the garden when the compost is used.
are slow to decompose although they may be added to the compost pile if one is not in a hurry. Their chunkiness and stiff mechanical properties help aerate a heap. They are somewhat more nutrient rich than sawdust.
are also called shoddy. See Hair.
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