Hans Jenny (7 February 1899 – 9 January 1992) was a Swiss-born soil scientist and expert on

pedology Pedology (from Greek: πέδον, ''pedon'', "soil"; and λόγος, ''logos'', "study") is a discipline within soil science which focuses on understanding and characterizing soil formation, evolution, and the theoretical frameworks for modeling ...

(the study of

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

in its natural environment), particularly the processes of soil formation. He served as 1949 President of the

Soil Science Society of America The Soil Science Society of America (SSSA), is the largest soil-specific society in the United States. It was formed in 1936 from the merger of the Soils Section of the American Society of Agronomy and the American Soil Survey Association. The So ...

Overview

Hans Jenny was born in

Basel Basel ( , ), also known as Basle ( ),french: Bâle ; it, Basilea ; rm, label= Sutsilvan, Basileia; other rm, Basilea . is a city in northwestern Switzerland on the river Rhine. Basel is Switzerland's third-most-populous city (after Zürich a ...

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

. He earned a diploma in

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people t ...

from the Swiss Federal Institute of Technology (

ETH Zurich (colloquially) , former_name = eidgenössische polytechnische Schule , image = ETHZ.JPG , image_size = , established = , type = Public , budget = CHF 1.896 billion (2021) , rector = Günther Dissertori , president = Joël Mesot , aca ...

) in 1922, and a D. Sc. degree in 1927 for a thesis on ion exchange reactions. Following an appointment at the

University of Missouri The University of Missouri (Mizzou, MU, or Missouri) is a public land-grant research university in Columbia, Missouri. It is Missouri's largest university and the flagship of the four-campus University of Missouri System. MU was founded in ...

, he joined the faculty of the University of California at Berkeley in 1936. International recognition came to Jenny after the 1941 publication of ''Factors of Soil Formation: A System of Quantitative Pedology''. His synthesis of field studies with the abstract formalism of

physical chemistry Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical me ...

set down the generic mathematical relationship that connects the observed properties of soil with the independent factors that determine the process of

soil formation Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order (anisotropy) within soils. These alterations ...

: s = f(cl, o, r, p, t, ...) where s - soil properties; cl - regional

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

; o - potential biota, r - relief; p -

parent material Parent material is the underlying geological material (generally bedrock or a superficial or drift deposit) in which soil horizons form. Soils typically inherit a great deal of structure and minerals from their parent material, and, as such, are ...

; t - time. Jenny left the

ellipsis The ellipsis (, also known informally as dot dot dot) is a series of dots that indicates an intentional omission of a word, sentence, or whole section from a text without altering its original meaning. The plural is ellipses. The term origin ...

open to indicate that there might be other variables in the function. In ''The Soil Resource, Origin and Behaviour'' (1980), Jenny redefined the soil forming factors as

state variable A state variable is one of the set of variables that are used to describe the mathematical "state" of a dynamical system. Intuitively, the state of a system describes enough about the system to determine its future behaviour in the absence of a ...

s and extended the effects to

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

properties. Parent material and relief define the initial state for soil development, regional climate, and potential biota determine the rate at which chemical and biological transformations proceed, and time determines the reach of these processes, and their expression in ecosystem, soil, vegetation, and animal component properties. One notable project was his study of the Mendocino

pygmy forest In anthropology, pygmy peoples are ethnic groups whose average height is unusually short. The term pygmyism is used to describe the phenotype of endemic short stature (as opposed to disproportionate dwarfism occurring in isolated cases in a pop ...

, a remarkable community of ericaceous and coniferous plant species whose stunted growth and grotesquely twisted morphology reveal a long and tortured struggle for survival on a 500,000-year-old marine

terrace Terrace may refer to: Landforms and construction * Fluvial terrace, a natural, flat surface that borders and lies above the floodplain of a stream or river * Terrace, a street suffix * Terrace, the portion of a lot between the public sidewalk ...

. The University of California's Jenny Pygmy Forest Reserve is named in his honor, and is found adjacent to Van Damme State Park. Jenny did much of his pygmy forest research within the boundaries of Jug Handle State Natural Reserve, which, as a result of Hans and his wife Jean's lobbying was designated the Pygmy Forest National Natural Landmark by the National Park Service in 1974. Jenny applied fundamental soil science to the problems of the day, when he wrote about "the rosy outlook that is sweeping the nation about converting

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of se ...

and

gasohol Several common ethanol fuel mixtures are in use around the world. The use of pure hydrous or anhydrous ethanol in internal combustion engines (ICEs) is only possible if the engines are designed or modified for that purpose, and used only in autom ...

...We are promised construction of ingenious machines that will pick up all crop residues in the fields and leaf litter and

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin ...

in the forests. The carbon and nitrogen cycles of ecosystems will be curtailed and soil stability endangered. Because of a possible climatic warm-up, we do not wish to accelerate humus oxidation and the concomitant flux of

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is tr ...

from soil into the atmosphere. I am arguing against indiscriminate conversion of biomass and organic wastes to fuels. The humus capital, which is substantial, deserves being maintained because good soils are a national asset."

Bibliography

* Jenny, Hans (1929) Relation of temperature to the amount of nitrogen in soils. Soil Science 27: 169–188. * Jenny, Hans (1936) Simple kinetic theory of ionic exchange. I. Ions of equal valency. Journal of Physical Chemistry 40: 501–507. *Jenny, Hans (1941). Factors of soil formation—a system of quantitative pedology. McGraw-Hill. * Jenny, Hans (1961) E.W. Hilgard and the Birth of Modern Soil Science. Pisa, Italy: Collana della Rivista ''Agrochimia.'' * Jenny, Hans (1968) The image of soil in landscape art, old and new. Pontifical Academy of Sciences Scripta Varia 32: 947–979. * Jenny, Hans (1980) The Soil Resource, Origin and Behaviour, Springer-Verlag, New York. * Jenny, Hans (1989) Hans Jenny. Soil Scientist, Teacher, and Scholar. Regional Oral History Office, The Bancroft Library, University of California–Berkeley, CA. * Jenny, Hans (1994
Factors of Soil Formation.
A System of Quantitative Pedology. New York: Dover Press. (Reprint, with foreword by R. Amundson, of the 1941 McGraw-Hill publication). pdf file format. * Jenny, Hans and K. Stuart (1984) My friend, the soil. Journal of Soil and Water Conservation 39: 158–161. * Jenny, Hans, R. Overstreet, and A.D. Ayers (1939) Contact depletion of bare roots as revealed by radioactive indicators. Soil Science 48: 9–24. * Jenny, Hans, T.R. Nielsen, N.T. Colemna, and D.E. Williams (1950) Concerning the measurement of pH, ion activities, and membrane potentials in colloidal systems. Science 112: 164–167.

Notes

References

University of California, Hans Jenny, in memoriam
* Amundsen, R., 2004
History of Soil Science: Hans Jenny
pdf format, in Encyclopedia of Soils in the Environment. Hillel, D., J.L.. Hatfield, D.S. Powlson, C. Rosenweig, K. M. Scow, M.J. Singer and D.L. Sparks. Editors. (2004) Four-Volume Set, Volume 1–4,

External links

Hans Jenny Memorial Lecture in Soil Science - The Genius of Soil
{{DEFAULTSORT:Jenny, Hans 1899 births 1992 deaths American soil scientists Soil scientists American geographers Swiss geographers Swiss emigrants to the United States University of Missouri faculty University of California, Berkeley faculty 20th-century geographers

Overview

Bibliography

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References

External links