Pedology

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Pedology is closely related to edaphology (the study of the influence of soil on living organisms) and consists of the study of soils as they are found in nature.

Pedology researches the origins of soil (pedogenesis) as well as the morphology of soils and then classifies them. Pedologists study the relationships between the pedosphere (the soil) and the climate in its many facets as well as the relationships of organisms in the soil (including plants and animals) as well as mineral compositions and soil’s effects on landscape and geography.

Soil layers near Glacier Park, Washington.  Heather Bleick, USGS, Public domain.
Soil layers near Glacier Park, Washington. Heather Bleick, USGS, Public domain.

During soil’s life cycle- if you will- layers are formed, creating depth and horizons in the composition of the soil that can be analyzed and studied for clues about the soil’s origins and nutrient values.

Pedologists combine the natural analysis of the soil and its environments with agricultural concerns and consequences, bringing together the entire field of soil sciences.

As well as the practical applications that soil leaves for farmers and, indeed, anyone who walks on Earth, pedologists can interpret the history of soil to make predictions on how things like global warming and pollution will affect soil in the future.

Rangelands of the desert Southwest can be in a degraded condition and lacking perennial vegetation, which can lead to exposed soil and erosion.
Rangelands of the desert Southwest can be in a degraded condition and lacking perennial vegetation, which can lead to exposed soil and erosion. Photo: Molly McCormick, USGS. Public domain.

There is a lot of historical knowledge that goes into pedology as well as knowledge about the climate, biology, hydrology, geology, ecology, and other essential environmental sciences. As you can imagine, almost anything on Earth either effects or is affected by soil- oftentimes both!

Knowledge of past events in Earth’s history like earthquakes, volcanoes, and meteor strikes are also essential when interpreting soil and making guesses as to the history of that particular sample.

Soil can be categorized into patterns using the horizons, or layers sound in a sample. As soil ages it grows more homogeneous; therefore a relatively new sample of soil might have many horizons, while a sample that has been undisturbed for many (many) years will look mostly alike.

A soil core sample taken near the Smith River in the Teshekpuk Lake Special Area of the National Petroleum Reserve - Alaska.  Photo: Brandt Meixell, USGS. Public domain.
A soil core sample taken near the Smith River in the Teshekpuk Lake Special Area of the National Petroleum Reserve – Alaska. Photo: Brandt Meixell, USGS. Public domain.

Factors like the number of soil horizons, position and age of the sample are used to determine what happened to the soil in the past, where it originated, and what could happen to it in the future.

Soil is constantly eroding and changing and is very different from place to place. Environments and climates (say, a desert versus a swamp) would contain soils that are chemically and compositionally very different from one another.

These differences can be used to trace the history of a soil sample from place to place, or to characterize it as being from a specific location. Over time soils are changed, created and destroyed, making this science hard to pin down in concrete ways oftentimes.

Red volcanic soil shows through a grassy area in the area around Puʻu o Lokuana.  Photo: NPS, public domain.
Red volcanic soil shows through a grassy area in the area around Puʻu o Lokuana. Photo: NPS, Hawaii Volcanoes National Park, public domain.

Pedologists understand the importance of knowing where soil comes from in order to determine what might happen to it in the future; how mankind has changed the composition of soils in different locations around the world and much more.

This is extremely hard to determine, however, due to the long geologic timeframe and relative lack of adequate ‘old soil’ samples that can be analyzed in comparison to newer samples to create a timeline of pedogenesis across the millennia.

The continued study of how soil is created, its patterns, and the future of its interactions with all living and non-living things is incredibly important.

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