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The Integrated Homestead:
Understanding Soil Fertility

Table of Contents for “The Integrated Homestead”

Industrial Food AlternativeTools and SpeciesSoil FertilitySoil CareInsectsGreenhouseForest GardenLivestockFungiFood StoragePoultryConclusion

The Living Soil

The first task, whether in the first day or the fiftieth year, is always: proper care and nurture of the soil. Our concern for the health and well-being of our soil should be on the same order as our concern for the nurture and health of our children.

The most important key to understanding soil fertility is to recognize that soil is not an inert substance—it is alive. It is true that soil contains tiny particles worn out of the parent rock, plus water and air. But a mix of rock particles, water, and air is not soil, and will never grow a thriving plant. The “soil food web” is the complex community of organisms living in the top layer of the soil profile—feeding, reproducing, competing, and cooperating in ways that alter the nature of soil in profound ways. These living organisms include bacteria, fungi, protozoa (single-cell animals), nematodes (minuscule non-segmented worms), arthropods (from microscopic to several inches long—insects, spiders, mites, centipedes, etc.), earthworms, and larger organisms such as moles, voles, even gophers, which have their role to play in recycling nutrients and maintaining good soil structure.

The sheer mass of living organisms in healthy topsoil is far from trivial: It has been estimated, for example, that total biomass of organisms in a prairie soil exceeds fifteen tons per acre, with the weight of the bacteria alone—invisible to the eye—totaling thirteen tons. A single teaspoon of that soil may contain 600-800 million individual bacteria from a possible 10,000 species; several miles of fungal hyphae; 10,000 individual protozoa; and 20-30 beneficial nematodes from a possible 100 species.

Natural Soil Ecologies

Consider this paradox: Why is it that, in natural soil ecologies the world over—forest, praire, bog, etc.—there is a spontaneous accumulation of soil fertility over time, while human agriculture has most often led to a decrease in soil fertility (never more so than in modern industrial agriculture)? What are the essential differences between natural soil ecologies and those under the impact of agriculture? Let’s focus on three.

Retention of energy entering the system

In natural soil ecologies, every bit of organic matter laid down on the soil—fallen leaves, plants that die, droppings of animals moving over it, dead animals—is utilized as food (energy) for the teeming community of living organisms in the soil food web. Whatever the nature of the organic matter, some member of the soil community has evolved to jump on it and utilize it as food—its means to support growth, maintenance, and reproduction. Whatever nutrients (potential energy) it cannot utilize itself, it excretes as “wastes,” but those metabolic byproducts themselves are passed on as energy sources to other organisms who can utilize them as food in turn. The end result of the intricate breakdown process is humus, the final residue of the parent organic materials, no longer recognizable as such, but visible only as a darkening of the soil. The microscopic humus particles are no longer a source of food for soil organisms, but they help with water retention, bond with nutrients in the soil and pass them on to plant roots, bind carbon into soil, etc.

Again, the food energy entering the soil food web (organic remains of plant and animal life) is passed from one “trophic level” (energy exchange pathway) to another. In other words, once potential nutrients for the soil food web enter the system, they are retained within the system because there are organisms feeding on their components at every stage of decomposition into their simple elements. That is, there is “someone” in the community adept at blocking any potential leak of nutrients (energy) from the system. If such potential nutrient leaks are constantly being “plugged,” the result has to be a net gain of fertility over time.

Contrast modern agriculture, which relies for crop fertility on highly soluble chemical salts which add no organic matter or longterm humus accumulation, and which quickly leach out of the soil. Perversely, what are intended as nutrients in the agricultural sector become in effect toxins as they accumulate in natural systems.

One could object that natural systems can accumulate soil fertility only because there is no net reduction from the system analogous to harvesting: In the case of agricultural lands, taking harvests off them has to represent a net loss of fertility. This observation ignores a key element in fertility accumulation—the fact that sunlight is constantly being added to the equation. Given the continual flow of sunlight-energy into the system, we can—with wise soil husbandry to prevent nutrient leaks—add to soil fertility even as we remove crops for consumption or sale.

Lack of disturbance

The accumulation of soil fertility occurs when there is little or no disturbance of soil-life communities. This is not to say that there are never disturbances in natural soil ecologies. But fertility accumulation occurs when this pattern—the continual passing on of food/energy sources from one trophic level to another—continues uninterrupted.

In contrast, industrial agriculture involves frequent and drastic soil disturbance, breaking down soil structure and inverting the natural layers of the soil profile. The living communities of the soil food web have to “start over” after each tillage. If the food web cannot fully reconstitute itself before the next round of tillage, the soil is on a spiral of decreasing quality.

Absence of unnatural chemicals

Plants and fungi are superb chemists, and make hundreds of thousands of chemical compounds, many of which they release into the atmosphere and the soil. But such naturally produced environmental chemicals are parts of the metabolic pathways to which members of natural communities have adjusted over deep time—indeed, they have become elements of the languages they have learned to speak with each other.

Present in the natural environment today, however, are artificially produced chemicals to which organisms have not had to adjust in the three and a half billion years of life on earth. Perhaps in a billion years they will adapt to these gifts from Monsanto and Cargill, but in the meantime, many of these compounds are seriously outside their range of adjustment—that is, toxic to living organisms.

Any agricultural practice based on imitating natural systems, therefore, will avoid altogether the introduction of man-made chemicals. We have to decide from the very beginning whether we are working in a Garden of Eden—or a zone of chemical warfare.