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Soils Basics

Soil profile.What is soil?

Soil isn’t dirt!

Soil is the unconsolidated mineral or organic material on the immediate surface of the earth. More importantly, soil forms the basis of an ecosystem, determining what lives above and below the ground surface. Dirt, on the other hand, is what’s under your fingernails and what you sweep off the floor.

Soils support plant and animal life both above and belowground. Billions of organisms make their homes in soils, including bacteria, fungi, protozoa, earthworms, and insects. The life forms that live within soils play important roles within the ecosystem, decomposing dead plant and animal matter, releasing nutrients for other organisms to utilize, creating pore spaces, and providing stability to soils.

Though often underappreciated, soils perform vital ecosystem functions. Soil provides support structures for plants to take root and also for buildings, roads, and infrastructure. Soils also play an important role regulating water movement through the hydrologic cycle. Another essential function soils play in ecosystems is cycling nutrients, breaking down dead plants and animals and storing nutrients for other organisms to access.


All contents copyright 2007. Arizona Board of Regents.