Hi James:
Characteristics of optimum black walnut planting sites related to soil properties: deep, fertile, moist, well-drained, and slightly acidic to slightly alkaline (pH 6.1-7.8). Deviation from these basic soil/site requirements generally results in poor growth or worse, mortality.
Fortunately, the USDA Web Soil Survey online website now features a "Walnut Suitability" option, thereby giving landowners and foresters basic guidance as to whether a particular soil type and site location is suitable for optimum black walnut growth and development.
USDA Web Soil Survey:
http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm
USDA Soil Survey Data (IL):
http://soils.usda.gov/survey/online_surveys/illinois/
Working with a professional forester, either an Illinois DNR district forester or a professional consulting forester, is strongly advised!
Directory of Professional Consulting Foresters:
http://web.extension.illinois.edu/forestry/pdf/tfb-nres-202.pdf
IDNR District Foresters:
http://web.extension.illinois.edu/forestry/pdf/tfb-nres-201.pdf