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Soil science

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Soil science is the comprehensive study of soil as a vital natural resource on Earth's surface. This discipline examines how soil forms, how it is classified, and how it is mapped across the globe. Scientists investigate the physical, chemical, biological, and fertility properties of various soils. They also study these properties in relation to how humans use and manage the land.

Soil sci
Soil sci

By understanding these complex systems, researchers can better address global challenges like food security and land degradation.

Soil exists within the pedosphere, which is one of the conceptual spheres used to organize Earth sciences. Within this sphere, the field is divided into two primary branches. The first is pedology, which focuses on soil in its natural setting. Pedologists study soil formation, chemistry, morphology, and classification. The second branch is edaphology, which focuses on how soils interact with living things, specifically plants. Both branches rely on the integrated principles of soil physics, soil chemistry, and soil biology to function.

Classification systems allow scientists to communicate about different soil types accurately. In 1998, the World Reference Base for Soil Resources (WRB) became the international standard for soil classification. The most recent version is the 4th edition, released in 2022. The WRB system is based largely on soil morphology, which is the physical form and structure of the soil. This differs from the USDA soil taxonomy, which includes soil climate as a major factor. Other systems include vernacular methods, which use descriptive terms like "red," "hot," or "sandy" to name landscapes.

Our understanding of soil has changed significantly throughout history. The earliest known classification system appeared in the Chinese book Yu Gong during the 5th century BCE. This ancient system divided soil into three categories and nine classes based on color, texture, and hydrology. In more recent history, Friedrich Albert Fallou and Vasily Dokuchaev emerged as the founders of modern soil science. Fallou was among the first to study the origins of soil. However, Dokuchaev's work is considered more significant to modern theory because he viewed soil as a distinct natural body.

Before Dokuchaev, many believed soil was merely a product of chemical changes in rocks. People often equated soil directly with the bedrock beneath it. Dokuchaev argued that soil has its own unique genesis and history of development. He proposed that bedrock transforms into soil through specific factors: climate, vegetation, country, relief, and age. This process is driven by the combined effects of water, air, and various living and dead organisms. This shifted the scientific view from soil as a "dead substrate" to a complex, living system.

Modern soil science addresses urgent global issues through diverse specializations. Researchers study microbiology, physics, and chemistry to solve problems like climate change. One major area of interest is carbon sequestration, which is the process of capturing and storing atmospheric carbon in soil organic matter. Scientists also monitor soil health through initiatives like the U.S. Soil Quality Initiative. This work helps provide long-term feedback on how well we are acting as stewards of the planet.

Global soils map USDA
Global soils map USDA

Managing these resources is critical as the global population grows and food consumption increases.

Practical applications of soil science are found in many different industries. Soil scientists work in land-based waste treatment, managing things like septic systems and biosolids. They help protect environmentally critical areas, such as wetlands, which support high biodiversity. In agriculture, they manage nutrients and water to optimize land productivity. They also work in remediation, which involves restoring damaged lands or cleaning up contamination. Even archaeologists use soil science to study the layers of earth at ancient sites.

Finally, soil science connects to the broader study of Earth's physical processes. It plays a role in understanding hydrology through concepts like depression storage capacity. This is the ability of land to retain water in pits, which helps prevent flooding and erosion. When water volume exceeds this capacity and the soil's infiltration capacity, it causes overland flow. This process can lead to significant landscape changes and environmental issues. Thus, soil science is essential for understanding the movement of water and energy across our planet.

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