Garden Smarts

Caring For The Soil

In its essence, all soil improvement involves the concentration of nutrients. Manure represents, in concentrated form, all the plants eaten by the animal that produced it; compost and leaf mold concentrate the nutrients from a variety of plants growing over a large area into a soil-like material. Cover crops, which grow by scavenging the depths of the soil for nutrients, concentrate all that goodness in the top few inches of the soil when we turn them under. In this chapter we will cover the enhancement and ongoing maintenance of fertility in the garden and then cover the basics of making a new garden.

     By volume, a productive garden soil is 25 percent air, 25 percent water, 40 to 45 percent minerals, and about 5 percent organic matter, including a whole Noah’s Ark of plants and animals ranging from microscopic fungi and bacteria to worms, insects, and burrowing mammals. A double handful of this soil contains more organisms, mostly microscopic, than there are people on Earth. Fueled by the heat and light of the sun, this community of soil life has, over eons, evolved complex strategies for extracting from the inanimate 95 percent of the soil all the nutrients life needs to prosper. The lush abundance of the tropical rain forests, which disappears once shortsighted farmers clear them for pasture to grow fast-food beef for export, and the meters-deep black soils of Ukraine and Illinois—some of the richest lands on the planet—were built up by this multitude and is the basis on which human life depends. Seen in this context, our ten thousand-year agricultural history is but a recent development, and the hundred-year-old invention of manmade fertilizers hardly a proven practice.

A Short History Of Fertilizers

One of the basic principles of organic gardening is to feed the soil and let the soil feed the plants; then the plants can feed you. Man must take his place in the community of organisms drawing its sustenance from, and adding to, the soil. We must leave the soil—and the Earth as a whole—better, richer, more productive than we found it. From a practical standpoint, there are two parts to the process of creating a continually healthy, productive garden: first, we must find (or rebuild) a fertile, friable soil; and second, we must maintain that fertility despite the drain of year-in, year-out harvest. Input must equal or exceed output; violate this equation and eventually your garden will decline.

     A simplistic understanding of this nutrient flow process often leads clean-handed theoreticians to skip the soil and concentrate on the plant. They assume that to grow a plant you need only apply inputs to some sort of medium that can hold the roots and support the plant, then inoculate it with a seed and stand back while the plant unfolds like one of those little smoke-and-ash snakes we played with as children. Unfortunately, this reductionist vision assumes that the chemist knows and supplies everything the plant needs; it assumes simply that if the plant is green and grows, all is well.

     The technical basis on which this belief is founded was developed by a German chemist, Justus von Liebig. He analyzed the chemical constituents of harvested plant tissue, and determined that it was largely composed of three elements: nitrogen, phosphorus, and potassium—the “N-P-K” listed today on every bag of purchased fertilizer. That there were hundreds, or maybe even thousands of other constituents, became of little concern; von Liebig found that plants responded to applications of simple compounds of these chemicals, particularly nitrogen.

     Some seventy years later, another German chemist named Fritz Haber developed a method of synthesizing ammonia (which is one part nitrogen and four parts hydrogen). Haber was awarded the 1918 Nobel Prize in chemistry for this discovery, which made the manufacture of nitrogen economically feasible—a breakthrough which is now coming back to haunt us. Haber’s process was used by the Germans not to feed the world, however, but to try to dominate it—to manufacture the explosives that led Kaiser Wilhelm into World War I. Haber became deeply involved in warfare chemistry and directed the first use of chemical weapons in 1915. By the end of World War II a whole class of chemical killers had been developed by both sides.

     Once hostilities ceased, all this technology was turned toward agricultural use, and the two major technological props that support current conventional gardening and farming methods are the direct results of this war research: Ammonia is now injected directly into the soil from tank trucks to provide nutrients that the dead land can’t provide, and chemicals that were created to kill our enemies are sprayed on the crops that we ourselves will eat. On the surface, gardening and farming have become a simple matter of inputs and outputs; but beneath the surface is a legacy of death, destruction, and pollution that continues to this day.

     The multibillion-dollar yearly agricultural chemical business is a direct result of this profound simplification. The Achilles heel of man’s manipulation of nature is the substitution of an economically efficient and profitable simplicity for the (seemingly) inefficient yet stable complexity of natural systems and methods. Someday we must pay to correct the damage wreaked on the Earth by the widespread, ill-advised acceptance of this Faustian bargain. Today immense amounts of ammonia are synthesized from methane (natural gas) and used to produce synthetic fertilizers. But less than half of that applied to the soil is actually used by the plants; the rest evaporates or leaches into streams, ponds, and groundwater, where it causes nitrate pollution so diffuse and widespread it may be impossible to clean up.

     Of course it’s possible to produce vegetable crops with chemicals alone, under artificial conditions; in fact it’s routinely done in hydroponic greenhouses. But while these vegetables may look normal, they lack some of the complex constituents of vegetables grown in a healthy, fertile soil. A 1992 article in the New York Times told of research which revealed that the plant pigment beta-carotene (responsible for the orange color of carrots), could help prevent cancer and heart disease. Beta-carotene, which is a precursor of vitamin A, is an ingredient in some over-the-counter vitamin pills; but the researcher who reported the findings recommended eating foods rich in beta-carotene rather than taking the vitamin pills. Why? Because beta-carotene is only one of about five hundred “carotenoids,” the larger group of related compounds to which it belongs. Other research had convinced him that combinations of different carotenoids are much more effective than beta-carotene alone. Carrots (and other foods like melons, kale, collards, winter squash, and pumpkins) contain a whole range of these carotenoids; the vitamin supplements, while they can be profitably manufactured, do not.

     The richer and more complex the soil in which plants are grown, the better they are able to find what they need to create a more complex and therefore more nutritious root, shoot, or fruit. The outputs cannot be any better than the inputs once the natural fertility of virgin soil, on which the plants draw, is exhausted, and the hidden but essential quality of the crops can only drop when they must rely solely on the NPK supplements they’re fed from a bag. To believe otherwise is horticultural hubris.

     So let’s take a look at N, P, and K, a what each does both in the plant and in the environment, and then at some of the other essential nutrients that are left out of the convenient modern “fast-food” fertilizers, along with the non-nutrient elements necessary for plant growth.

The Real Story of N-P-K (Plus)

Nitrogen—the N of N-P-K—is the most important plant nutrient, because it is an essential building block of chlorophyll (the green pigment in leaves, without which photosynthesis, and therefore plant growth, cannot occur) as well as a number of other enzymes and hormones central to the plant’s growth processes. It is also the most likely nutrient to be deficient. Its source is the air we breathe, and it exists in the soil only as a byproduct of the soil’s teeming microbial life, rather than as part of the earth’s mineral store of nutrients. When nitrogen is deficient, plants concentrate it in their youngest leaves, so the older, larger leaves turn pale, and in severe cases may wither and fall. Ninety-nine percent of total soil nitrogen is in the organic matter, both living and dead, that the organic gardener is primarily concerned with, and only about one percent is in the soluble inorganic forms found in most quick-fix fertilizers.

     Because nitrogen is so essential to plant health, and its supply so fleeting, most plants will consume it far beyond their needs in an orgy of greed, throwing off their own metabolism in the process. Delayed maturity, uneven ripening, and overly succulent growth are all signs of a nitrogen excess. An excess of nitrogen will lead to harvest problems as well. The harvest taken from plants grown with too much nitrogen will not store well, and is likely to be low in vitamins A and C, as well as high in accumulated nitrates, which are toxic.

     In the garden environment, nitrogen is in a constant state of change and movement, cycling perpetually through the air, soil, water, and the bodies of plants and animals. It enters the soil in rainwater, or through bacterial extraction from the air (discussed in more detail later in this chapter), and in the form of applied fertilizers, either organic or chemical. It can be lost back to the air through volatilization, or washed away by rain and irrigation water; otherwise it is available for use by soil bacteria, plants, and the animals that eat them, and then released again upon their death and decomposition.

Phosphorus, represented by the letter P in discussions of chemistry, is also critical to plant growth. While nitrogen fuels the plant, phosphorus is essential to the distribution and storage of that energy in the form of sugars and starches. Without sufficient phosphorus, plants again will be stunted, though the leaves instead of being pale will be purplish from the accumulated sugars created by photosynthesis that cannot be utilized in the absence of sufficient phosphorus. This often occurs in early spring, as phosphorus uptake and utilization is retarded at low temperatures. Phosphorus moves through the garden environment primarily by being used by plants and animals and then recycled in the form of compost or manure, though most manures are relatively low in phosphorus.

     Phosphorus is usually added in the form of mined phosphate rock, bone meal, or phosphate fertilizers made from them by treatment with sulfuric acid. Excessive phosphorus is rarely a problem, since nitrogen is more easily absorbed by plants. Where uptake is excessive, though, it can affect a plant’s ability to take up other necessary elements that the plant needs in trace amounts. Once applied, phosphorus will stay put, as it bonds easily with many other soil minerals like aluminum (in acid soils) or calcium (in alkaline soils). Because it becomes “tied up” at high or low pH levels (which we will discuss shortly), phosphorus is much more easily available to plants if the soil pH is kept close to neutral. Organic gardeners prefer to use phosphate rock for building this important soil component, since the nutrients are released slowly over time by the action of soil microbes breaking down its compound forms.

     Third of the Big Three nutrients is potassium, listed as K (for its Latin name Kalium). Potassium regulates the processes of plant food creation, transportation, and storage that are fueled by nitrogen and facilitated by phosphorus. Unlike nitrogen and phosphorus, however, potassium is not a constituent of plant cells themselves; rather, it is part of the fluid that fills plant tissues, contributing to the ability of stems and leaves to hold themselves upright. Biennial root crops like carrots and beets are also dependent on potassium to complete conversion of sugar to starch, which makes overwintering of the root and subsequent seed production the following season possible.

     Potassium’s cycle in the environment is similar to that of phosphorus, though it is not long held in soil organic matter; it is, however, more available in most manures and in compost made from fresh green materials. While it is mobile within the plant, potassium does not leach, or wash out of the soil, readily; when applied in the form of mined rock power (such as greensand or granite dust) it is available for long-term use by plants. Other good organic sources of potassium are green manure crops such as ryegrass and buckwheat (discussed below) and wood ash, which also contributes a small amount of phosphorus. It is possible to apply too much potassium—especially in small gardens—if you use large quantities of wood ash; this may then lead to a phosphorus or magnesium deficiency.

     Three so-called secondary nutrients are now given more credit for the health of growing plants than at first thought: calcium, magnesium, and sulfur. Sulfur never used to be a problem, and it still isn’t for organic gardeners. Even old-time synthetic fertilizers contained sufficient sulfur (as an impurity) for most plant needs. But newer, more refined fertilizers are “purer,” and so sulfur deficiencies have become more of a problem. Deficiency symptoms are similar to those of nitrogen, with which it works in the synthesis of amino acids and proteins that the plant needs. In most manures, composts, and cover crops, sulfur is present in the proper proportion to nitrogen.

      Magnesium is the central element in chlorophyll, to which the nitrogen is chemically bound. It performs a function similar to that of hemoglobin in human blood; without it the plant will be anemic. It also relates to phosphorus the way sulfur does to nitrogen. It is sufficiently important to humans that even when a deficiency causes no appreciable damage to plants, their value as food will be lower due to its lack. Unfortunately, potassium, magnesium, and calcium all compete for uptake by plants, and unless care is paid to keep them in balance, deficiencies can result. Fortunately, most composts supply ample magnesium. The simplest solution when starting a new garden in areas with acid soils is to use a high-magnesium, or dolomitic, limestone, thus adding both magnesium and calcium at the same time.

     Finally, calcium is important because of the critical role it plays in the structure of cell walls, especially at the growing tips of both roots and tops. But calcium deficiency problems with maturing plants, such as tipburn in lettuce and cabbage, or blossom-end rot in tomatoes, can exist despite relatively abundant calcium in the soil, due to problems with its extraction from the soil by the plant. Specific solutions to these kinds of problems are discussed in the individual plant entries of this site.

     A number of other nutrients are needed by the plants in your garden in very small amounts, and are thus called micronutrients. A balanced program of soil enrichment and maintenance (as outlined over the next few chapters) pretty much guarantees that none will be seriously deficient, but if in doubt, kelp meal can be used as a micronutrient fertilizer to establish starter amounts of a wide range of different elements. Made from dried seaweed, which has drawn its substance from the diverse ingredients of the world’s oceans, kelp meal is rich in minor nutrients. Just a partial list of the elements contained in dry seaweed includes, beyond nitrogen, phosphorus, and potassium: boron, copper, iron, manganese, molybdenum, zinc, calcium, iodine, a range of sulfates, and—perhaps most important of all—up to 25 percent alginic acid, which stimulates biological activity in the soil and improves soil structure.

That is the key to avoiding nutrient deficiencies in an organic program of soil-building: balance. As we’ve seen, the excessive buildup of one essential nutrient often leads to the displacement of another. Blind feeding of the plants in the garden often leads to impoverishment of the garden itself, and, in the long run, poorer plants.

Manure

A quick review of a table of nutrients in manure will show that there are significant differences in the nutrient levels (and balance) of fresh animal manures. Rotted manure, which has been allowed to sit, out of the rain yet kept moist and sufficiently packed down to exclude air, is usually richer by weight (than fresh manure it loses much of its weight during the rotting process), and is also more stable in terms of its nutrients, since microorganisms have already had a chance to do some of their work. While the balance of nutrients in manure is relatively good, improper use or storage can cause a significant loss of nitrogen.

     However, it isn’t necessary to store manure or wait for it to rot. Fresh manure can be spread directly on a new garden; if turned under immediately, there will be only minor losses of nitrogen and other nutrients, though planting should be delayed three weeks to a month to allow it to break down and stabilize. But once the garden has been established, direct application may only be feasible in the early spring and late fall, as fresh manure is too strong for most plants.

     Fresh cow or horse manure (without bedding) applied in the fall, at the rate of two to three bushels (about 100 to150 pounds) per hundred square feet, will supply enough nutrients for general vegetable cropping. If stronger manures are used, decrease this volume a bit; if there is a lot of bedding mixed in, increase it. One important point: fresh manure should be turned under immediately, or significant amounts of nitrogen will be lost to the atmosphere or to runoff.

     Country gardeners may want to keep a few chickens or rabbits, or even a horse; from then on, manure will be available whenever they like. Others, without the room to keep animals, can often locate a livestock or poultry keeper with manure to spare. In fact, they may be glad you asked. For most gardeners, though, the occasional use of purchased organic fertilizers—either dry bagged manure or in granular form—plus composting, may be the most reasonable plan of action. At the end of this chapter we will discuss purchased organic fertilizers in a bit more detail.

Compost

There is no doubt that composting is the heart of modern organic gardening. Though I value the books and other tools I inherited from my grandfather, the most important thing I got from him when he retired was his compost pile. For, while you can buy books or tools, compost must be made. The new gardeners among you may not yet fully appreciate this truth; the old hands certainly will.

     Composting is a form of recycling. The harvest from many plants is only a small bit of its bulk. We eat practically the whole lettuce plant, but with corn, for example, the ear that we eat represents only about 10 percent of the plant; by composting its stalk we return the remaining 90 percent of its nutrients to the garden. Seen in this way it is not so surprising that composting would build long-term fertility into any soil, since its nutrient “savings account” is being constantly added to.

     This is aside from the cash and resource savings that a compost pile represents. Earlier, I alluded to the energy cost of synthetic fertilizers. Almost 2 percent of the natural gas consumed in this country is used to manufacture nitrogen fertilizers; there is the equivalent of one-third to one-half gallon of gasoline in every pound of nitrogen fertilizer in terms of the energy consumed. That energy is nonrenewable; once burned, it is gone, and not only unavailable for our further use, but a pollutant that fouls the atmosphere.

     What is most wasteful about manufactured fertilizers, though, is that one-third to one-half of the nitrogen and one-fifth of the potassium and phosphorus in them is washed away into our streams, ponds, and groundwater aquifers before plants can use it. There, these nutrients are no longer an asset, but another pollutant that someday must be removed. In fact, nitrate pollution of water supplies is already becoming a serious problem nationwide. Before blaming this entirely on the farmers, consider the aggregate impact of 50,000 suburban homeowners—each dosing his or her parcel of lawn with a combination fertilizer and herbicide—on the underground water supply of even a small city. When you think what happens to a gentle spring rain percolating down through the soils of that average community, it is no surprise that bottled water sells so well!

     The energy of a compost pile—the bacterial energy of decomposition, which takes refuse that would otherwise end up clogging the community landfill, and turns it into free fertilizer—is not just renewable, but constantly going on all around us in a never-ending cycle of decay and rebirth. The essence of the organic method is to tap into those natural cycles and let them do the work for us. Because of this, as well as for its obvious material benefits, composting is central to organic gardening.

     The more diverse the ingredients that go into a compost pile, the more nutritionally balanced the finished product will be. One of the great advantages of compost over purchased fertilizers is that it’s loaded with concentrated micronutrients. When you shred and then compost the leaves of a shade tree, you are bringing to your garden nutrients collected by that tree from a much greater depth than the vegetables you grow could ever reach. When you compost the household food waste produced in your kitchen you are collecting nutrients that are, literally, from all over the world. And once you’ve brought those nutrients into your garden, composting keeps them there. Keep in mind that this means you should never put anything on your compost pile that has been treated with pesticides. Storebought produce may not represent much of a threat to the community of microorganisms that devour it, but grass clippings from a golf course or park recently treated with pesticides can wreak havoc with your composting operation, so it is best to avoid such materials entirely.

     Compost, with its broad range of nutrients. but low apparent “analysis”—that is, the official N-P-K listing, which indicates the immediately available nutrients—is a stable, slow-release fertilizer whose nutrients will not easily wash out. In laboratory experiments, a highly composted soil sample can be drenched with up to seven times its weight in water spread over a dozen washings that mimic ample summer rains, without losing a significant amount of its mineral nutrients. The nutrients in a fertile, friable soil are so tightly bound to the complex soil particle structure that they are released primarily through the chemical transfers initiated by plant roots, not simply dissolved in water and washed away. The standard analysis does not pick them up because they aren’t there in the form that the tests are looking for; they don’t become “available” until the acids and enzymes secreted by plant roots and by the multitude of soil microorganisms make them available, on an as-needed basis.

     So while the advocates of quick-acting soluble fertilizers may be technically correct (in the narrowest sense) when they say that plants can’t tell where a given amount of nutrient came from, they miss the point. The efficiency of slow-release, recycled nutrients is simply better, more varied and balanced, and less prone to causing problems than the packaged product. The nutrients are available over a longer period, to be taken up at the plants’ will, without the danger or possibility of overdose, or creation of pollution problems elsewhere. Over time this balanced storehouse of both macro- and micronutrients increases. Of course, organic materials can create problems if used improperly: the runoff from fresh manure, unwisely spread on fields that will not be promptly plowed, can wash into ponds and rivers, polluting them just as quickly and surely as a synthetic fertilizer. Proper materials are only part of the organic method; proper handling of those materials demands equal attention.

Not even the most devoted adherent of bagged fertilizer will claim that it improves soil structure, but compost helps make cold, soggy soils like ours warmer and drier, and yet will help make sandy and gravelly soils more drought-resistant as well, bringing each soil extreme toward that middle ground that most plants favor: a loose, loamy soil with a neutral pH.

     It does this by improving what is called the “crumb structure” of the soil. A fertile, friable soil somewhat resembles moist gingerbread. The addition of compost builds this kind of soil not only through its own physical properties, but by the soil life it includes. Tiny, colorless fungi, responsible for the initial stages of decomposition in a compost pile, not only bind soils with their far-reaching, threadlike bodies, but produce elements that bacteria then turn into a kind of glue that causes loose soil particles to clump together into “aggregates.” Many species of soil fungi in this community also directly help plant roots gather food, in exchange for plant foods they are unable to produce for themselves.

     Earthworms are one of the most indispensable inhabitants of both the compost pile and the garden. The mucus coating that makes them feel slimy is what allows them easy passage even through tough soils. This lubricant remains on the walls of their tunnels, binding the soil particles there in the same process of aggregation that is so crucial to good soil structure. As the earthworm eats its way through the material in the compost pile, it mixes the raw materials with its own pH-balancing digestive secretions and the diverse bacterial population of its gut. As a result, earthworm castings are one of the best manures available, and an active earthworm may well produce its own weight in castings daily.

     Not only are manufactured fertilizers unable to equal this improvement program, this soil-building function (despite their higher long-term cost), but they are caustic chemicals and actually degrade the soil, because they kill or drive off the fungi, the bacteria, and the earthworms—all of the beneficial inhabitants of a fertile soil. These valuable residents will return in time; but by using manufactured fertilizer, the bag gardener not only pays out hard-earned cash, but creates a potential pollution problem and sets back the development of a truly fertile garden soil—all for a quick shot of growth. This is even more of a folly during dry periods, because organically fortified soils hold water better in droughty weather and are thus able to continue providing nutrients, while soils with poorer structure, even if fortified with soluble nutrients, cannot pass them on to the plants if there is not sufficient water to dissolve them. After a rain there will be a quick flush of growth as the nutrients are picked up by the water, made temporarily available to the plants, and then just as quickly washed away. The companies that make these products know this. Look at the ads they use to sell them; you’ll notice they emphasize rapid growth and the size of the crop, but not its flavor and nutritional content.

Making Compost

There are relatively fast methods of making compost which require a fair, but not unreasonable, amount of effort and attention, and then there are slower but less arduous methods. In both cases the process by which garden refuse, kitchen garbage, manure, yard trimmings, and decomposable trash are transmuted into the black gold of compost is similar. Whether a freestanding compost pile is built, or the materials are kept in a bin or other enclosure during the composting process is immaterial; only the appearance is different.

     The fast method is like building a fire, and it differs from the slow method solely in that air is actively incorporated into the pile. The fuel is carbon: dry plant matter like leaves, straw, hay, or dry weeds and yard trimmings. The heat comes from nitrogen. The surest form of nitrogen to fuel the compost pile is manure. Where it is available it should be used (with the exception of manure from pets or people, which, unless specially treated, may contain disease pathogens). Where manure is not available the readiest sources of nitrogen are freshly cut grass clippings, freshly pulled weeds, and kitchen garbage: that is, vegetable and fruit trimmings, coffee grounds, spoiled leftovers, and the like. It also makes sense to include a bit of soil or compost from an earlier pile, which will serve as a “starter” by providing a population of decomposing organisms early on (though they would eventually find the pile anyway). Such compost starters can also be bought ready-made if a starter source isn’t available.

     Two last elements that are important are moisture, and the size and shape of the pile. The microorganisms that drive the composting process forward require moisture. If the materials used are not succulent, the pile should be watered as it is built, and periodically there after, to keep it uniformly moist. When the materials are just glistening and damp to the touch, but not soaking wet, conditions are likely to be ideal. The size and shape of the pile become important as it heats up (which increases the biological activity within speeds along the composting) because the pile must have enough bulk in relation to its surface area so that it generates more heat than it loses. Many experienced composters actually insulate their piles with a layer of straw or manure to conserve its natural heat. An effective minimum size for freestanding piles seems to be about four feet on a side (or longer if you need more compost) and about four feet in height. Some commercially manufactured compost bins are insulated, and so make it possible for a smaller volume of material to attain the critical heat levels needed for fast composting.

     The ingredients should be kept in proper proportion when assembling a compost pile. A common rule of thumb is that you’ll want, by volume, four to five times as much carbon-rich material as there is nitrogen-rich refuse. These difference kinds of materials are kept well mixed by layering them on the pile as they are collected. Two of the most common products of the American yard, however, require special attention. Autumn leaves, unless shredded before piling, tend to pack down and exclude air; lawn clippings are so rich and succulent that, unless dried first or mixed thoroughly with drier material, they will rot into a slimy mess instead of composting. Both materials are excellent sources of nutrients, though, and composting them saves money and landfill space, at the same time providing nutrients for your garden.

One of the more difficult tasks in composting is to make sure that air can get to all parts of the pile throughout the decomposition process. The bottom layer of the pile should be made of shrub prunings, twigs, or other light materials. As the pile increases in size, larger branches or even poles can be laid horizontally on top, and then later, during its decomposition, withdrawn to allow air to enter. Some other methods of getting air into a compost pile to speed its decomposition are to stick vertical lengths of drainage tile into the first few layers of the pile and then build it right up around them; or to poke holes with a bar or piece of iron pipe once the pile is finished; or, as many gardeners do, turn the pile with a manure fork each time it starts to cool down, placing the materials from the outside of the pile on the inside and vice versa. For gardeners with limited space and fairly formal yards, there are manufactured compost tumblers that will accomplish this process of reaeration without the heavy lifting.

     The basic proportion between the dry, fuel-type materials in the pile and the moister, heat-supplying materials should be four or five to one. The soil or compost fraction usually covers lightly each layer of the nitrogenous material to hold in its moisture and discourage scavenging animals (not a problem if a bin is used to hold the compost). In our hot piles we alternate six to eight-inch layers of dry matter with one to two-inch layers of manure and one-half to one-inch layers of compost from the previous pile. Many composters, including us, like to add a bit of phosphorus to the pile, as it is proportionately low in both compost and manure. We use rock phosphate, and sprinkle three or four handfuls over the compost layer before starting again with the dry layer. Piles that use no manure tend to be a bit more acidic, and wood ash or bone meal would make a good addition, as they would effectively raise the pH toward neutral a bit.

     This layering process should continue until the pile is four feet tall. Water it if necessary to ensure that there is sufficient moisture for decomposition to proceed. Within a few days the pile should begin to heat noticeably. During cool weather it may actually steam, but during the spring and summer months (when composting proceeds most quickly, anyway) you can check it simply by thrusting your fist into the pile. In the center it may well be too hot to touch, between 120˚ and 140˚ F (49˚ and 60˚ C). Once it begins to cool down—if you want to keep the process moving as quickly as possible—consider supplying more air, either by turning the pile, or by the other methods mentioned above. If you are of a precise mind, you can check its progress with a thermometer. We use a small, inexpensive meat thermometer: after thrusting my fist into the pile, I stick the thermometer into the end of the passage so that it is within the heart of the pile. As soon as the temperature drops below 100˚ F (38˚ C), I consider the pile ready for turning.

     A properly proportioned pile, made with the right ingredients and closely managed, can be ready for use in as little as two weeks, having been turned twice or three times over that period. This is particularly true if the materials from which the pile is built are shredded before composting; the smaller particle size makes the work of decomposition easier for the microorganisms in the pile. If you have a garden spot that you want to improve as quickly as possible, simply scour the neighborhood for leaves, hay, stable cleanings, sawdust, and manure, rent a shredder, and make a whole series of piles. Even without turning—if you build the piles properly, with provision for getting air to the center—you should be able to produce large amounts of ripe compost in a month.

Lazy Composting

My grandfather’s garden was well established by the time I was born, and he had his methods so well worked out that this kind of hurry-up composting was unnecessary. Instead he had adopted a method of slow composting that, while it took quite a while to produce finished compost, yielded him a steady supply with very little labor. He called it the “lazy man’s method,” and being lazy myself, it’s my method of choice as well. Here is how he described it in his book, Step by Step Organic Vegetable Gardening:

     Start by laying out a rectangle about five feet by twelve feet on a level piece of well-drained ground, marking the corners with stakes. Then lay up an outside wall of one or two thicknesses of sod or cement blocks. The system requires the maintenance of three compost piles, one of which is available for current use, one of which ages for a year, and a third which is being built during the current season.

     Build the pile using all decomposable garbage from the house, and from your neighbors as well, if you can get them to sort their waste, covering each layer with a layer of hay or leaves and a thinner layer of topsoil before it has a chance to become nasty. Early in the spring there will not be much beyond kitchen scraps to put on the pile, but as summer comes on there will be garden weeds, pea vines, etc. As the pile grows, keep building up the sides with sods or other material that will stay in place, and keep covering the succeeding layers with topsoil, or, if available, with thin layers of manure.

     In the fall put all the crop wastes from the garden onto the pile: squash, tomato, and bean vines; the remains of cabbages, cauliflowers, broccoli; and so forth. At the end of the season, cover the pile with sods root-side up (so they won’t grow), or with manure, and then leave it for nature to take its course. By the time the pile is two years old, having taken six months to build and eighteen months to cure, it should be fully decomposed; any material that is not can be placed on the bottom of the new pile.

     This kind of composting is also called anaerobic composting because it proceeds without worrying about getting air into the pile. It is essentially controlled rotting, and, as my grandfather was fond of pointing out, the only real difference between well-rotted manure and compost is that the manure went through the gut of an animal first. Both began as vegetation, but the manure was predigested by the gut bacteria, acids, and enzymes of the animal before being deposited and allowed to rot. The process of both rotting and composting is digestion, and either rotten manure or plant compost can be used to fertilize and improve the soil structure of your garden. Which you will use depends largely—as does the method of composting you choose—on the particulars of your situation.

    If you have access to good rotted manure, or a place to compost it, it is the simplest product to use; if not, then composting will provide you with just as many of the benefits, though with a bit more effort. If you have plenty of space and abundant raw materials, but are short of time to manage a quick compost pile (or just don’t need that much compost), by all means follow my grandfather’s long-term, low-work method.

Composting Materials Chart

Carbon/Nitrogen Ratio of Common Compost Materials

Material                                             C/N Ratio

Grass Clippings                                    20 to 1

Weeds (green)                                    19 to 1

Leaves                                                60 to 1

Paper                                                 180 to 1

Kitchen Scraps                                     15 to 1

Sawdust                                               450 to 1

Hen Manure (no litter)                           7 to 1

Hen Manure (w/litter)                           10 to 1

Straw                                                  100 to 1

Seaweed                                              25 to 1

Pines Needles                                        70 to 1

Corn Stalks                                            60 to 1

Alfalfa Hay                                           13 to 1

Using Compost

Gardeners with access to manure will most likely reserve their compost for use as a special fertilizer for favored plants, and guidelines for this kind of treatment can be found in Chapter 8, under the individual vegetable entries. It is applied as a side dressing during times of peak nutrient demand, or used to amend the soil at the spot where transplanted crops will be set.

     Those whose gardens depend on compost and soil-building cover crops for their fertility should spread it more generally on the beds, just before planting, at a rate of two to three bushels per hundred square feet. That is 100 to150 pounds of compost, or about 1 to 1 1/2 pounds per square foot. A well-made compost pile measuring four feet square at the base and four feet high will contain sixty-four cubic feet and weigh about a ton, which should be enough compost to fertilize a garden of up to two thousand square feet. The same size pile could help make a smaller garden into a superproductive plot virtually overnight.

Store Bought Organic Fertilizers

Unfortunately, not all organic gardeners have access to manure or the room for a compost pile or tumbler. Perhaps your garden is just a few window boxes on a balcony. Or it could be that backyard space is precious, and there is only room for a couple of half-barrels and a small growing bed between the sidewalk and the front porch. You can still treat properly what soil you have by using purchased organic fertilizers and soil-builders instead of synthetics. You may even be able to buy fully prepared compost from the county or town in which you live, as many local governments now sponsor composting projects at local landfills.

     With the growing interest in organic gardening, though, many companies have brought what they call “organic” or “natural” fertilizers to market, and you are likely to find one or more of them available at your local hardware store or garden center. Just be sure to read the label of what you buy, since the dream of profits has led more than one businessperson down the road to subtle deception. A few products are little more than standard synthetic fertilizers with a bit of some organic material such as fish meal added (and then emblazoned in large type on the bag). These kinds of products will not build the soil.

     Here’s what to look for when you buy organic fertilizer. First, check the N-P-K listing on the bag. If any of the numbers is above eight, look for a list of ingredients; most organic materials are lower than that in immediately available nutrients, which is what the number must legally mean. Remember, that is the advantage of organic materials: their nutrients are not immediately available, but rather are released slowly, over time, at a rate the plants can use without waste.

     Second, scan the list of ingredients for words like ammonium, muriate, urea, nitrate, phosphoric, or superphosphate; if these words or their variants are part of the ingredients, don’t buy. The words phosphate and sulfate themselves are not necessarily indicators of processed or synthesized materials; but if combined with any of the key words above, they are. Other ingredients to watch out for are cottonseed meal and leather tankage, not because they aren’t natural (nonsynthetic) products, but because they are frequently contaminated with harmful residues, thus making them suspect for use in an organic vegetable garden. The same points apply to liquid fertilizers.

     When using commercial organic fertilizers, follow the instructions and the recommended application rates listed on the package. Don’t double up because the listed N-P-K is lower than what you might be used to using. And be careful to keep track of your soil’s organic matter level; these purchased fertilizers, unless they are made from composted manures (many are), do not add organic matter to the soil—and organic matter is at the heart of organic gardening.