“The changing model of soil” revisited

In 1961, the late Marlin G. Cline wrote a remarkable essay entitled, "The Changing Model of Soil" for the 25th Anniversary Issue of the Soil Science Society of America Proceedings. Cline was most impressed with how geomorphology was enriching pedology, and with the increasingly sophisticated views of soil time and of the processes of soil formation. We revisit Cline's general objectives by re-evaluating the changing model of soil from the perspective of the early 21st century, and by taking stock of the application of soil models to contemporary needs and challenges. Today, three ongoing changes in the genetic model of soil have far-reaching consequences for the future of soil science: (i) that soil is being transformed globally from natural to human-natural body, (ii) that the lower boundary of soil is much deeper than the solum historically confined to O to B horizons, and (iii) that most soils are a kind of pedogenic paleosol, archival products of soil-forming processes that have ranged widely over the life of most soils. Together and each in their own way, these three changes in the model of soil impact directly human-soil relations and give structure and guidance to the science of anthropedology. In other words, human forcings represent a global wave of soil polygenesis altering fluxes of matter and energy and transforming the thermodynamics of soils as potentially very deep systems. Anthropedogenesis needs much better quantification to evaluate the future of soil and the wider environment.