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The Grundy soils of Nebraska

Hayes, F.A.
Agronomy journal 1927 v.19 no.4 pp. 311-323
soil types, soil compaction, soil classification, drainage, climatic zones, vegetation, soil parent materials, Nebraska
Observations on the Grundy soils of Nebraska may be summarized as follows: 1. These soils occupy over 4,000 square miles, occurring chiefly in the southeastern and east central parts of the state where they occupy the more nearly level loess plains. 2. About 75% of the soils lie between 1,650 and 1,850 feet above sea level. 3. There is uniformity in climate, vegetation, and parent material throughout the area. 4. The upper three horizons of the profile are persistent in the area. They are a structureless mulch, a laminated horizon, and a granular zone, each of which is quite friable and remarkably uniform in structure and relative position but varies, within narrow limits, in color and texture and considerably in thickness. 5. The fourth horizon is the one of maximum compaction. It varies decidedly in color, density, and structure, but does not attain the friable condition existing in the corresponding layer of the Holdrege and Marshall soils. Varying combinations in color and consistency give rise to three well-defined variations. In one of these the color may range from grayish brown to very dark grayish brown, but the gray and brown shades dominate and the material is never black. It probably varies sufficiently in density to warrant a separation in soil mapping based on this feature alone. Where the material is extremely dense and clay-pan like it might, for instance, be correlated as brown clay-pan Grundy, and where it is decidedly less compact but still remains too dense for Holdrege or Marshall it might be called brown soft-pan Grundy or correlated with a new series. The third variation differs from the brown clay-pan chiefly in its darker color, being very dark grayish brown to almost black. This color difference is thought to be sufficient to warrant recognition in the final correlation of the Grundy soils and the darker material might be classed as black clay-pan Grundy. 6. The fifth horizon is more valuable than any above. It is characterized by differences in the content and distribution of lime. Throughout the southeastern part and including about 50% of the Grundy soils of Nebraska, there is a definite zone of lime accumulation beneath which carbonates disappear so far as could be determined in the field. In the western part of the Grundy region there is another area in which the profile contains a definite zone of lime accumulation. In this area, however, some lime continues to below 12 feet or the maximum depth of observation. In the northern part, and including the remainder of the main Grundy region, is a small area in which no zone of lime accumulation is developed. Any carbonates which may occur lie much deeper than in the other areas and are uniformly distributed throughout the underlying loessial deposit. In much of this section lime reaction does not occur within 10 or 12 feet of the surface. 7. In conclusion, it is advisable to mention that the information secured in these studies of the Grundy soils, and to a less extent those of the Marshall series, warrants some changes in the location of the line separating the lime of accumulation from that of the parent material in Nebraska. It is realized that any single line dividing these two methods of lime distribution will be more or less faulty, due to the presence of isolated bodies characterized by one mode of distribution and surrounded by another. Nevertheless, a general line of separation can be drawn on either side of which the mode of distribution will remain remarkably constant. From the information secured such a line would run about as shown on the map.