Hans Jenny

Factors of soil formation : a system of quantitative pedology

Factors of soil formation : a system of quantitative pedology / Hans Jenny ; foreword by Ronald Amundson. p. cm. Originally published: New York : McGraw-Hill, 1941. With new foreword. Includes bibliographical references and index. not include the modern Dover Press Forward, which is not public domain material.

The Place Of Humans In The State Factor Theory Of Ecosystems And Their Soils

Landscapes and their soils often are studied and described by the clorpt equation of the state factor theory. It links properties of animals, plants, and soils to the factors climate (cl), organism (o), topography (r), parent material (p) and time (t) or age of an ecosystem. Humans are implicitly contained in the organism factor o, and this study attempts to conceptualize explicitly the role of humans as a state factor in ecosystem study. After a brief exposition of state factors and their sequences, humans are symbolized by their inheritable attributes, their genotypes, oh, and their external phenotype expressions h. Humans possess culture, c, defined as “products of human work or thought.” When humans enter an emerging ecosystem they bring along a cultural inheritance, ci. Both oh and ci are treated as independent state factors, whereas h and culture elements c are considered being dependent on oh, ci, cl, o, r, p, t, … The concepts are probed for Pacific island cultures, for cultures of Indian hunting tribes of the Great Plains, for midwestern rural trends, and for soil cultivation and plant growth experiments. Golden Gate Park in San Francisco comprises three consecutive chronosequences differing in the human state factor.

Ecosystems and Soils

On the 3000 mile flight from New York to San Francisco the plane traverses a landscape of gigantic proportions. The rugged mountains, smooth hills, rolling plains, broad valleys, rivers, and lakes are ecosystems with wide variations in climate, bodies of water, soils, vegetation, animal life, and human activities. This book brings into focus the soil resource, its creation by nature, its variation over continents, and its husbandry by man.

State Factor Topography

The immense tectonic plates that make up the Earth’s outer shell may slide beneath one another and initiate volcanos or collide with each other and push up and fold mountain ranges. Precipitation decimates the peaks, erodes the hill soils, and covers the valleys with new parent materials.

Pedogenesis of Horizons and Profiles

When uniform rock material transforms to soil, horizons appear at various depths, recognizable as dark humus layers, gray and reddish color bands, zones of clay accumulations, carbonate strata, and iron and silica hardpans.

Biomass and Humus

Starting with rock, water, and air, only the blue-green algae and the purple bacteria are able to put together a viable combination of C, H, O, and N atoms in the form of biomass. The higher plants assimilate carbon dioxide of the air but depend on microbes to supply available nitrogen. All soil organisms respire and consume plant materials, directly or indirectly. During metabolic conversion dark humus substances appear and accumulate in the soil. The path from greenery to blackness is reconnoitered in ensuing sections.

Biotic Factor of System Genesis

Planet Earth houses millions of species of plants and animals and all may perform as biotic factors.

The Time Factor of System Genesis

During a hundred million years a given locale on Earth may slowly sink below sea level, then rise to mountain heights, be temporarily covered by glaciers, be eroded, and finally subjected to aridity. Chronosequences deal with brief segments of geological history.

State Factor Climate

To begin with a historical note, the documented recognition of climate as a molder of soil is but a century old, though earlier de Saussure had suggested in his Voyages dans les Alpes (1796) that climate is responsible for variations in contents of soil organic matter.

Behavior of Ions in Soils and Plant Responses

The chemical elements that function in ecosystems appear as neutral atoms, molecules, and electrically charged ions.