Summer 1998

 
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Wild Soils

by

Stephen Lewandowski

For most people, the concepts of "soil" and "wild" could only be linked as an oxymoron. After all, soils are among the most common things in the world, obvious as the dirt under-foot, dust in the wind or mud on your boot. And wilderness is an area undisturbed by human activity, empty and pathless. What do they have in common? Can soil be wild?

Soils are generally composed of 40-50 per-cent mineral particles (rock dust), 20-25 percent water (less in the upper layers, more in the lower), 20-25 percent gases (more in the upper layers, less in the lower as replaced by water) and 2-15 percent humus.

Humus consists of the living and the dead. From this once-living organic matter, plants ex-tract phosphorus, potassium, nitrogen, calcium and magnesium. The presence or absence of or-ganic matter drastically changes soil's ability to absorb and retain water.

Probably the least-well-known wildlife in the world are soil organisms. Most live in the top foot of soil and range in size from micro-scopic to easily visible, and in numbers from several per acre to billions per ounce. The extent and importance of life in the soil should lead us to define soil as a living medium.

Root hairs threading through soil channels, bacteria and fungi active in decomposition, pro-tozoa-hunting bacteria, slime molds consuming bacteria and fungi, mycorrhiza soil fungi living in symbiotic relationship with the roots of vas-cular plants, nematodes and earthworms process-ing vegetable and mineral matter, voles and moles tunneling—all of these modify soils and give them special characteristics.

Many soil organisms are extremely small, but they compensate in number for their tiny size. More than 70 species have been collected from a square foot of rich forest soil.

The total animal population of forest soils approaches 10,000 organisms per square foot. These microorganisms produce enzymes and cause physiological processes that recycle and detoxify both natural and man-made organic substances.

Life teems underfoot Based on its mysterious inhabitants and processes, soil is clearly "wilderness" territory. While organisms of the topsoil are the best known of the soil inhabitants, they are by no means the only denizens of the soil. Scientists as Penn State University have collected and studied thousands of organisms living hundreds of feet below the Earth's surface. Top-soil organisms are largely aerobic (using oxygen to produce energy), but subsoil organisms are anaerobic and produce energy through denitrification (changing organic acids to nitrogen gas), sulfate reduction (changing sulfate to hydrogen sulfate) and methanogenesis (changing organic acids to methane).

Soil is a nutrient sink, with building blocks of life stored in minerals, organic matter and microorganisms. Agriculture aims to manipulate the reproductive potential of soils through mechanical and chemical means, but human attempts to "tame" the soil have not been informed by a knowledge of soil physics, chemistry or microbi-ology. In Soil and Civilization, Edward Hymans characterizes man's destructive relationship with soil as parasitical. Our actions on the soil may have had damaging effects beyond our knowl-edge and ability to repair.

In pursuit of abundant food and fiber, our clearing, tillage, fertilization and pest control methods have depleted organic matter, allowed topsoil to erode, disrupted ecosystems and need-lessly poisoned communities of beneficial organisms and groundwater. The clearing of forests and 300 years of cultivation of Northeastern lands have depleted the soil's humus. Much of the original topsoil is gone, the loss of the nat-ral nutrient base masked by the addition of industrial fertilizers.

Each of these factors, taken alone, reduces the "fertility capital" stored in soil. Taken together, soil scientists warn, the synergistic and cumu-lative effects of the changes unknowingly begun in soil may affect our life on Earth.

Resanctifying the Land

Perhaps we will heed the advice of the sus-tainable agriculture movement. Researchers such as Wes Jackson at the Land Institute [2440 E. Water Road, Salina, KS 67401-9051] have been seeking to model agricultural systems on ecological principles. Some farmers have switched to minimum tillage and introduced cover and "green manure" crops to their rotations to mimic natural systems and protect the resource base.

Some of the "new" practices promoted by sustainable agriculture advocates are as old as farming itself. Although we can demonstrate their beneficial effects, we cannot always say why they work.

Pre-industrial cultures personalized the principle of soil fertility. The concept of the "little people who live under the hill"—mysterious subterranean creatures who guarded fertility and remind humans of their responsibilities—is echoed in the "jungies" of the Iroquois and the "vetters" of Norwegian myth. These storied little people and mythic talking animals link cultural and natural worlds.

Teacher and soil scientist Hans Jenny has become an advocate of the preservation of natural, undisturbed soils set aside as "benchmarks for assessing man-induced soil changes and for preserving unique segments of landscape...for teaching and research." He raises fundamental questions about soils—i.e., "What does nature have in mind, what is her goal of soil evolution?"—and answers in a way that links the evolution of soils with the evolution of species.

In 1789 Abner Barlow and his ox tilled the ground in the village of Canandaigua to plant the first wheat in western New York state. Though his plot of ground had been cleared by the indigenous Seneca, the land outside the village was still covered by huge oak, chestnut, maple, white pine and beech forests. Beneath these trees lay the native soils, whose mineral textures had been formed, transported, laid down and shaped by the glaciers. In 10,000 years between the last glacial retreat and Abner's plow, perhaps ten more inches of soil had formed from fractured bedrock and accumulated vegetable matter. Abner Barlow and ten generations have since gone into the ground that they once farmed. The silt loam that Abner tilled has disappeared beneath lawns, houses and pavement. When he tilled the ground was it wild? Covered with domestic structures, is it tame?

Both the quality and quantity of nature's bounty rest heavily on the productive capacity of wetlands, estuaries and a thin layer of living top-soil. Though we have done our best (but more often our worst) to domesticate soils, they still lie outside our reason. Soils remain mysterious, despite our best attempts to know and manage them. Soils are wild to the extent that they are unknown territory—self-regulating and beyond our control.

1994, Stephen Lewandowski
From Earth Island Journal, pages 36 and 37, Spring 1994
Index to articles by Stephen Lewandowski
 
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