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CHAPTER 1
The Soil
Anyone can recognize a fertile soil. Its color is dark brown to black, with a moist look; its texture spongy; its smell earthy, redolent of spring, musky and wholesome. It looks alive. Our awareness of soil is instinctive, from knowledge acquired in ages past, then wired into our DNA and connected to our sense of well-being. We trust fertile soil to grow the quality of food we want to eat. Seeds sown in it spring to life and grow vigorous plants, with vibrant colors. They produce food bountifully. And we know that when we eat that food our bodies will be nourished as they were meant to be.
Few soils a gardener begins with are fertile enough to fulfill that promise, but all of them can be made so. The process is simple — it's a lot like cooking.
The Nature of Soil
To understand soil better, let's start with the popular parable "Stone Soup." This is a simple tale of soldiers returning from the Napoleonic Wars. As they passed through a poor peasant village they were able to get a meal by telling the inhabitants they would feed them stone soup. After placing a stone in a large kettle of water over a fire, and claiming that was sufficient for the meal to come, they proceeded to hint that maybe a pinch of parsley, some carrots, a few potatoes and such would make the stone soup taste just that much better. Little by little, the initially reluctant villagers volunteered to donate one or another of the suggested "extra" ingredients. The result was a delicious communal meal enjoyed by all.
WHAT SOIL IS MADE OF
Building fertile soil is a little like making stone soup, because every soil started out as stone or rock. Whether the soil particles in your backyard are now the size of sand (the largest) or silt (smaller) or clay (the smallest), or, as is usually the case, a mixture of the three, they were all originally, and still are, rock. Over passing millennia the rocks have been slowly reduced to their present particle size through the effects of freezing and thawing, the erosive action of wind and water, and the grinding of glaciers. The type of rock the particles originally came from influences their eventual size and determines their mineral content.
Those particles by themselves won't do much for the garden, but add the second key ingredient in soil — water — and the process begins. Not too much water, as with a real soup, but just enough to keep the rock particles consistently moist. Excessive water keeps air from being able to enter the small spaces between the particles, and it's important for air to enter. Air is the third key ingredient in soil. With those three — rock particles, water, and air — soil formation is off and running. For the earliest living organisms on our planet, that was enough, for they were able to survive by extracting mineral nutrients from rock. But as they died and decomposed, their remains began to add a fourth key ingredient: organic matter.
And that's the living earth under your feet. It is tempting to refer to soil as having four simple components. But just as with making soup, even a few additions, when combined, become something greater than their sum, a complex blend of flavors. Luckily, you can enjoy that soup without knowing what chemical reactions make it smell and taste so good.
The same goes for soil. As long as you concentrate on adding more of that essential fourth ingredient, organic matter, to the stone, water, and air you started with, you can create a fertile soil without even knowing how it happens. The whole range of benefits you get from the organic matter in the soil is only just beginning to be understood and fully appreciated by agricultural science. But we do know that if we amplify organic matter, plants will thrive. This is true for recent additions of organic matter, such as the roots of the lettuce you just picked, which were left behind in the soil and are starting to break down. It's also true for the older, biologically stable, well-decomposed organic material we call humus.
THE LIFE IN A HEALTHY SOIL: Because the soil in which the bean plant grows is rich in organic matter, it's teeming with creatures that give it fertility, aerate it, decompose wastes, make nutrients available to plants, and maintain a loose, crumbly structure. Most are invisible to the naked eye, but life on earth wouldn't be possible without them.
SOIL IS ALIVE
The story gets even better. In your garden there is a fifth component that arises out of all these parts, the most important one of all: soil life. It's not an ingredient like rock particles, water, air, and organic matter, it is the force that ties them all together. A marvelous living world exists under your feet and it makes the living world aboveground seem almost empty by comparison. The British scientist J.B.S. Haldane is reported to have said, jokingly, "If one could conclude as to the nature of the Creator from a study of creation it would appear that God has an inordinate fondness for stars and beetles." Beetles are, in fact, 20 percent of all known living organisms. And once you begin to learn about life in the soil, you wonder if Haldane might have better noted a million-fold greater fondness for soil dwellers in general. It has been said that if you include both the ones we can see with the naked eye (such as earthworms, ants, and beetles) and those that are only visible under a microscope (like bacteria and fungi), there are more living creatures in one cup of fertile soil than in the whole of the world above ground.
The sheer mass of soil creatures is as impressive as their numbers. An acre of rich pasture land, the produce of which is sufficient to feed a 2,000-pound steer grazing aboveground for one entire year, harbors a weight of creatures belowground equal to that of the steer itself. The life processes of those soil creatures within the matrix created by our four original soil ingredients are what provide the fertility to grow the grass that feeds the steer. Soil microbiologists spend their careers identifying, counting, and categorizing these organisms into family, genus, and species, and observing how they interact with one another and with plants. But the home gardener can benefit from all this underground activity without that level of scientific expertise. All you need to know is that soil creatures work best and are most productive in creating fertile soil if you give them three things: a soil that is not too acidic, an adequate level of moisture, and plenty of organic matter.
Soil Test
TAKE A SAMPLE. For a pure sample, use stainless steel implements and avoid touching the soil with your fingers. Dig samples from at least 12 places from a depth of 6 to 8 inches.
END IT OFF. Mix the soil thoroughly and fill the box or bag provided. Fill out the form the lab gives you, label the container, mail it, and await the results.
SOIL PH
Many garden soils are too acidic, or tend to become more so over time. Soil acidity does not promote a mellow environment for most soil creatures, just as stomach acidity is not pleasant if you overindulge. In both cases an antacid helps to return the chemical reaction back to neutral. The antacid for soils is called lime and comes as finely ground particles of limestone, a calcium-containing rock. Most soil creatures are happiest when the soil is neutral to just slightly acid. Think of the soil inhabitants as your soil fertility staff. They work for free, so your responsibility is to give them a pleasant work environment by making sure the soil pH (the scale for measuring soil acidity) is between 6 and 7.
The best way to determine your soil pH is to have a soil test done. There are simple home kits that test for pH, but one done by a soil lab will give you information about your soil's mineral content as well. Your local Extension Service or state university will do this for a modest fee, and will usually send you instructions on how to collect the soil sample properly, as well as a mailer in which to submit it. The basics are also shown in the photo at left. (In case you'd like a more detailed report than your state office supplies, it can probably recommend a competent private soil-test lab.) After you send in your sample you'll get back not only an analysis of your soil, but also advice on how to remedy any soil deficiencies. Ask for organic recommendations when you fill out the form.
In general, it takes 5 to 10 pounds of lime per 100 square feet of soil to raise the soil's pH one interval on the scale — say, from 5.5 to 6.5. It takes more lime to raise the pH of clay than it does that of sand, so if your soil is sandy add 5 pounds, and if it's clay add 10. (See the chart on page 17 to find out which you've got.) Bags of lime are available at farm and garden supply stores. If you know you're going to need to raise your soil's pH, you'll want to have enough lime on hand when it's time to start spreading it and other soil amendments on the ground as you begin your new garden. Thereafter, pH may not be much of an issue, because as more organic matter is added to the garden, year by year, it tends to buffer the effects of pH. Most gardeners, however, do add lime every four years because limestone contains calcium, an important plant nutrient.
Nourishing the Soil
Once you've provided all those soil inhabitants with a great working environment, your second responsibility is to feed them. It couldn't be easier. Their food is organic matter of all kinds, and includes anything that was once alive and growing: the leaves on the forest floor, the dead grass stems in a field, the fallen fruit under a wild apple tree, the wilted flowers in a vase, the celery leaves you discarded when making dinner. This is the basis of Mother Nature's soil fertility system, a fact known since the earliest days of agriculture. The Greek philosopher Anaximander wrote 2,500 years ago, "Everything that forms in Nature incurs a debt which it must repay by dissolving so that other things may form." In other words, everything that once grew eventually rotted back down to provide growing conditions and nutrients for future plants and animals. And best yet, the process is cumulative. In undisturbed conditions, organic matter in the soil increases, and so does soil fertility.
Your job as a gardener is to make sure that a natural increase in fertility is a part of your plan. To do that you have to embrace the idea that all this life in the soil is good — all those bacteria and grubs and spiders are important and helpful to you. Although our society seems to have a passion for sterilizing everything, that is not desirable for your soil. When conditions are favorable, the good bacteria run the system.
Some things, such as the weather, you can't do anything about. Normal amounts of sunshine, rain, and benign temperatures are obviously beneficial to plant growth, and usually you at least have an idea of what to expect in the climate where you live. Things that you can control, such as the air, moisture, pH, and organic matter in the soil, are up to you. Gardening is a lot like raising a puppy, and instinct will tell you what to do. Warmth, air, light, food, care, and space to romp are all qualities that vegetables need just as much as puppies do. And soil creatures need them too. The world of soil, plants, and gardens is a wholly connected, heart-beating, pulse-pounding, interacting community of separate parts working in harmony with one goal: life. Under the conditions of the average home garden, maintained with lime and organic matter, the system is on your side.
WHERE TO BEGIN
The most fertile soils exist in those parts of the world where nature's processes, such as wind and flowing water, have caused extra rock particles and organic matter to be deposited. River-bottom land, where erosion upstream has swept down particles that are left behind after floods, is one example. Areas of very deep fertile soil known as loess, formed by soil particles carried by the wind, are another. Soils downwind of active volcanoes may have benefited from the accumulation of volcanic ash — newly created rock particles that often have excellent inherent fertility. Soils that were once lake or sea bottoms before being raised by the earth's geologic activities retain the layers of nutrients deposited in their formative years. Muck soils are ones that have accumulated abundant organic material under swamplike conditions and become extremely fertile ground when the excess moisture is drained. Growers lucky enough to garden on river-bottom land, or loess soil, or drained muck have a head start on making the soil fertile, thanks to nature's generosity.
It could be, however, that the originally good soil in your backyard no longer resembles the gift of nature it once was. It may have been left open to erosion, or doused with chemicals, as so many of today's lawns are. It may have been removed during construction or, if it's former farmland, exploited for harvests year after year, with no thought given to maintaining levels of organic matter and minerals. Fortunately, these momentary defects can be fixed. As Tuisco Greiner, a 19th-century garden writer said in the delightful prose of his day, "But it is with soils as it is with people when they get into a bad way. If the foundation — the texture, the quality, the character — is good, they can be redeemed very easily." There's work to be done on such soils, but it is not difficult.
Gardeners in the less-favored areas will have to work a little harder. Where we live, on the Maine coast, another geologic process, glaciation, scraped away most of our soil and left us large stones and occasional patches of bedrock that have not changed much in the 10,000 years since the glaciers receded. But a determined gardener can do what nature has not had time to do yet by following the same principles that created all those naturally fertile soils. One of the classic examples of determined soil-building concerns the Aran Islands off the coast of Ireland. There, over centuries, the inhabitants created acres of fertile earth by layering sand from the beach with seaweed from the ocean, on top of bare limestone bedrock. The 1934 film Man of Aran celebrated both the farmers' efforts at soil creation and the self-sufficient lifestyle that arose as a result. Resolute gardeners everywhere have been inspired by their example to realize that all soils can be made fertile and productive (or just plain "made") with whatever rock particles and organic matter are available.
But isn't the process of overcoming poor soil conditions and creating a garden expensive? Isn't it necessary to buy a lot of stuff? What about all those gardening stories about adding up the costs and ending up with a $100 tomato? True, the $100 tomato is certainly possible if you spread expensive amendments on your garden in hopes that fertile soil might develop a bit sooner. But by understanding the natural soil-creation process we've described, and thinking in terms of inputs of management and knowledge rather than inputs of purchased goods, you can create a rich garden soil without a rich man's budget.
When soil particles flow down a river to be deposited on the floodplain or are carried by wind to fall on the soil surface, the result is an incrementally deeper, thicker layer of good soil — the topsoil. By digging a hole with a shovel and looking at the soil profile on the wall of the hole, you can see how deep the topsoil goes in your garden. It's the darker brown layer at the surface. Many studies have shown that simply making the topsoil deeper can result in better growing conditions for garden vegetables. So part of the soil improvement efforts in our own garden were aimed at increasing the inadequate 3 inches of topsoil nature had given us. Eventually we ended up with 10 inches of beautiful dark, rich, fluffy soil, created almost entirely from resources available on our property.
There were a number of steps to the process. First, we simply collected topsoil that we dug from other parts of the yard where it wasn't needed, such as the site of a new tool shed and the place where we laid a stone patio, and added that to the surface of the garden. Next we took a good look at the nature of our soil.
SOIL TYPES
Soils are composed of a mixture of particles of varying sizes, and are classified according to which sizes predominate. There are a number of subcategories within the major ones listed below, as defined by the USDA, but these are the ones most frequently used by gardeners in describing their soil.
SOIL TEXTURE
The texture of your backyard soil — whether it's fine particle clay, coarse particle sand, or the more friendly silts that lie between — will be an important consideration when trying to build fertile earth. That texture is the result of massive forces such as retreating glaciers, up-thrusting mountains, the depositing of water-carried or wind-carried soil particles, and erosion in general. It could also be the result of bulldozers and backhoes excavating the land on which your home stands. Fortunately, there is one solution to all the problems that your soil texture might cause you: making and spreading organic matter, especially in the form of compost. Whether the dominant particles are sand, silt, clay, or that ideal combination of all three known as loam, organic matter improves them all.
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Excerpted from "The Four Season Farm Gardener's Cookbook"
by .
Copyright © 2012 Barbara Damrosch and Eliot Coleman.
Excerpted by permission of Workman Publishing.
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