Nitrate Leaching Class Ranges

This is a statewide Arc/Info data set of nitrate leaching class ranges for soils in Illinois. It was generated to aid in determining aquifer sensitivity to nitrate leaching in Illinois. The source map was digitized at 1:250,000, but was developed from source data mapped at 1:15,000. The publication of this map was at 1:500,000. Nominal scale is 1:250,000. This data set contains the four trimmed range values presented on the ISGS map Nitrate Leaching Classes of Illinois. Range values were determined for the nitrate leaching classes in each soil association to give an indication of the variability within a specific leaching class. This data set is necessary because each soil association (in data set *path_name_suppressed*/no3leach) could have only a single leaching class value assigned to it. In this data set the item NO3INDEX_RANGE contains a 10% trimmed range for the leaching class characteristics of each association. This item was calculated by sorting the component soil series in order of their leaching characteristic within the association. The trimmed range is the domain of leaching characteristic values between the 90th and 10th quantiles in the sorted list. The range was trimmed (by 10% at either end) to reduce the significance of extreme values. These data were used as an overprint on the published map. (see cross references).