Validation of Soil Based Productivity Models for Determining Target Yield on Coal-Mined Lands in Reclamation.

Prime farmland reclamation success in Illinois and Indiana is based on crop production of coal-mined land compared to an approved reference area or other guideline (e.g., Agricultural Lands Productivity Formula used in Illinois).  Often, if coal-mined land does not meet target crop yields, crop yield testing can continue for many years until a productivity standard is met.  A need exists to expediate this process and to evaluate cropping potential of coal-mined land.  In our study, georeferenced corn, soybean, and wheat yield, cone penetrometer test (CPT) at different soil depths, elevation (including terrain derivatives), and apparent electrical conductivity (EC_a) data were collected (crops grown depend on fields) for three fields at the Lewis Mine site in southwestern IN, three fields at the Cedar Creek Mine site in western IL, and one field at the Wildcat Hills Mine site in southern IL.  Crop yield, elevation, terrain derivatives, and EC_a values were matched with each penetrometer point.  Soil based productivity models were constructed using logistic regression to assign probabilities of meeting target crop yield for a given field and site.  Results show that target crop yield across years is primarily influenced by compaction and water related variables.  We suggest that modeling this variability will provide recommendations for future management strategies to identify and increase yield potential of problematic field areas.