Research reports and data can be found at http://www.farmresearch.com/frec313/

We propose to do a partial update of the survey from the late 1960s, by collecting samples from a small number of selected fields throughout Illinois, sampling at depths to 24 inches. The intent is to provide a check-up of the current nutrient profiles compared to those of 40 years ago. If major changes are found from this sampling compared to the 1960s survey, there may be a need for a more extensive survey in future years to guide nutrient management.

Original 'Nutrient Levels in Illinois Soils' article published in the ILLINOIS RESEARCH, University of Illinois Agricultural Experiment Station, Summer, 1968.