| Soil | Mean (mg·kg−1) | Coefficient Variation (%) | Comments |
| Alred Amagon Broseley Calhoun Clana Commerce Dubbs Foley Frenchmill Haymond Hildebrecht Irondale Kaintuck Killarney Knobtop Lilbourn Malden Menfro Overcup Portageville Reelfoot Rueter Sharkey Tiptonville Wakeland Wilbur | 0.5 0.5 0.3 0.6 0.3 0.4 0.4 0.9 2.4 0.7 0.5 1.0 <0.1 2.2 0.6 0.4 0.2 0.4 0.7 1.0 0.6 0.2 1.0 0.5 0.7 0.5 | 45 49 29 13 22 53 35 18 35 65 39 23 -- 54 26 32 23 38 36 28 20 39 38 33 32 67 | Eluvial horizons below detection No significant soil profile variation No significant soil profile variation No significant soil profile variation No significant soil profile variation Slightly greater in eluvial horizons Slightly greater in eluvial horizons Slightly greater in eluvial horizons Irregular distribution Greater in eluvial horizons Slightly greater in argillic horizon No significant soil profile variation All horizons below detection limit Irregular distribution No significant soil profile variation No significant soil profile variation No significant soil profile variation No significant soil profile variation Slightly greater in deeper argillic horizons Slightly greater in eluvial horizons No significant soil profile variation No significant soil profile variation No significant soil profile variation Slightly greater in eluvial horizons No significant soil profile variation No significant soil profile variation |