Is the Traditional Pedologic Definition of Soil Meaningful in the Modern Context

The definition of soil is an important part of communication about soil, and it is important to have effective communication with other scientists, politicians, an interested public, and others with an interest in utilizing soil information. Initially soil science was focused primarily on agricultural applications, but in recent decades the use of soil information has expanded to include areas like land use planning, environmental applications, human health, and food, water, and energy security. Pedologists now include urban and other anthropogenically disturbed environments in their studies in addition to the traditional natural and agro-ecosystems. With these expansions in the application of soil information it is natural that some have raised the question of whether a new definition of soil is needed. Here we investigate that question by exploring whether the traditional pedologic definition of soil is meaningful in the modern world, with its expanded applications for soil knowledge. The current pedologic definition of soil includes the following key elements: (i) soils are natural bodies, (ii) soils are both spatial and temporal, (iii) soils form at the surface, (iv) soils are the result of complex biogeochemical and physical processes, (v) soils are capable of supporting life, and (vi) soils can be mapped at appropriate scales. We conclude that a definition that includes the six key elements listed above, with perhaps some minor modifications, is able to incorporate the expanded applications of soil information in the modern world.