Science on Tap:”Sixty Harvests Left”: Estimates of Soil Degradation

Soil fertility forms the foundation of agriculture, and many estimates exist for the long-term fertility of agricultural soils worldwide. Famously, one UN report suggested in 2015 that "there are sixty harvests left", but how accurate was this bold prediction that frightened so many people? Dozens of similar models and predictions exist from the late 19th century to the present, and their compilation and comparison may yield important information as to what makes a soil fertility model of high or low quality or value. How many of these models are anecdotal or based on field data? What types and quantities of such data are required and attainable to make a strong prediction of the future of agriculture? Although it is unlikely that there are "sixty harvests left", what quality and quantity of research must be done to generate an accurate prediction? 
Dr. Michael J. Braus is Senior Research Scientist at Growcentia, Inc., a young Ag Tech company located in Loveland, CO, that designs and manufactures microbial soil amendments, organic fertilizers, and biopesticides. Mike performs laboratory research and bioinformatics for product development and provides subject matter expertise in the fields of soil microbiology and biogeochemistry.