Soils from the orders Alfisol, Inceptisol, Mollisol, Ultisol, and Oxisol contained exchangeable K (neutral 1N NH4OAc) and boiling 1N HNO3 extractable K varying from 31 to 358 ppm and 62 to 652 ppm, respectively. Total K varied from 1,780 to 14,200 ppm. Quantities absorbed from each soil by 7 cuttings of perennial ryegrass (Lolium perenne) in the greenhouse ranged up to 13 times that of exchangeable K and up to 5 times that of HNO3‐extractable K. Total plant uptake represented 3.5 to 29.7% of total soil K. In no soil did K become limiting in the first four cuttings. However, except for the Mollisols, uptake decreased abruptly in the later cuttings, indicating very little “slowly” available K. Even though exchangeable K and K removed by strong acids were highly correlated with plant uptake (r = 0.744** to 0.881**), all extractants greatly underestimated actual plant‐available K under intensive cropping. Total soil K did not significantly correlate with plant uptake (r = 0.211).
Soil maps provide a tool for rapid, low‐cost delineation of river flood plains, based on the difference in morphology between soils frequently flooded and soils free of flooding. Very rare floods along the Mississippi River inundated over 99% of the soils that would be expected to flood but in addition flooded 7% of the terrace soils. Flooding predicted with soils information was compared with flooding predicted with an engineering study for small streams in a mature landscape in southwestern Wisconsin. For a 100‐year synthetic flood an agreement of ±4.5% was obtained. Comparison of flooding with soil types for a small stream in a recently glaciated landscape in southeastern Wisconsin indicated that alluvial soils flood frequently and, in addition, that soils with restricted drainage and soils of fluvial origin also flood frequently. Some of the data are inconclusive, owing to the lack of precise flooding information to serve as a basis of comparison. In areas where man‐made works do not appreciably alter the stream regimen and where extensive flood plain areas must be delineated, it appears that accurate soil maps, properly interpreted, will give a good estimate of areas subject to flooding.
Soil columns from two Typic Glossoboralfs were dissected to separate albic tongues and argillic B horizon material. Tongues and B horizon material have similar coarse/fine (50‐20µ/20‐2µ) silt ratios in the upper B horizon indicating that tongues could have been formed in place by eluviation of clay from certain zones of the B horizon.Lower in the B horizon the tongues consistently have different coarse/fine silt ratios than does adjacent B horizon material. Mineralogical analysis of silts gave no indication of differential weathering of quartz, alkali feldspars, or mica which together make up 85 to 90% of the fine silt (20‐2µ). The particle‐size distribution of silts in the lower albic tongues is taken to indicate that translocation of silts and sands has been involved in the formation of these tongues.Higher proportions of quartz, feldspars and mica in the coarse clay (2‐.2µ) of upper albic tongues indicate that montmorillonite, vermiculite, pedogenic chlorite and kaolinite have been preferentially removed. This, and the mineralogical similarity of fine clay (<0.2µ) between eluvial and illuvial zones, indicate that clay translocation in these soils is accomplished primarily by movement of clay particles in suspension without appreciable dissolution of crystal structures.Spodic horizons have begun to form in the albic horizons of some Glossoboralfs of the study area and Spodosols are common in coarser parent materials. Processes of illuviation inferred from this investigation, however are greatly different from those generally considered typical of Spodosols.
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