Soil Quality Assessment: John Doran's Challenge and the Scientific Community Response.

In 1992, Dr. John Doran was asked to provide an ARS peer review for a manuscript reporting on several biological, chemical, and physical properties for soil samples collected from Rozetta and Palsgrove silt loam soils in Wisconsin after 10 years of various crop residue management and tillage treatments. John’s primary comment was that this was a good paper, but couldn’t we do more by using this data to actually assess the soil quality impact of these management practices. In response to John’s challenge and using newly acquired knowledge of systems engineering, a series of hand-drawn scoring functions were developed based upon literature values, experience, and expert opinion and used to provide unitless 0 to 1 ratings for several of the indicators. This provided a science-based method to combine ratings for bulk density, pH, fertility, earthworms, and several other indicators into an overall soil quality index. It was also the beginning of what would evolve into the Soil Management Assessment Framework (SMAF) and many vigorous scientific debates regarding the relative merits of soil quality versus quality soil management. This presentation will review the tremendous impact that John’s simple challenge had on the entire soil science community during the next 20 years, culminating with current examples of how the SMAF is being used globally to assess long term effects of soil management.