Scientists urge broader soil definition from Earth fields to icy worlds
Soil is essential for farming, food production, and environmental protection, yet scientists continue to debate how soil should be defined. New research suggests that traditional definitions may be too narrow for modern discoveries. A broader scientific view could greatly expand soil research on Earth and beyond.
The study was conducted by Dr. Aaron Lee M. Daigh, an associate professor at the University of Nebraska–Lincoln, where he works in the Departments of Agronomy and Horticulture and Biological Systems Engineering. Dr. Daigh is also a soil physicist and vadose zone hydrologist with extensive experience in soil and water research.
“Soil science has enormous, untapped potential,” said Nebraska’s Aaron Lee M. Daigh. “If we define our subject too narrowly, we artificially limit our science.”
Even fresh volcanic ash or newly deposited river sediments can be considered soil, even before plants or animals appear.
Another major proposal focuses on soil depth. Instead of choosing a fixed depth, such as a few feet, soil should be defined by how deep surface forces can move water, gases, energy, and nutrients.
This active zone, where changes constantly occur, marks the true lower boundary of soil. In many places, this means soil is much deeper than previously believed, which could impact irrigation planning, groundwater protection, and crop management.
The most unusual idea involves icy soils. Snowpacks and icy surfaces on Earth, as well as frozen surfaces on moons and dwarf planets, could also qualify as soil. These icy materials are shaped by environmental forces just like traditional soil. A new scientific term has been introduced to describe soils made mainly from ice rather than rock.
These ideas do not replace practical soil definitions used by farmers or policymakers. Instead, they support a long-standing approach to having two definitions. One is a simple, practical definition used in agriculture and land management. The other is a broader scientific definition that grows with new knowledge.
Expanding the definition of soil matters because clear definitions help scientists work better. They guide sustainable farming practices, improve environmental protection, and support research on climate change. They also open doors to space exploration and the study of life beyond Earth.
By looking at soil in new ways, scientists hope to unlock discoveries that benefit agriculture today and prepare humanity for future challenges on Earth and in space.
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