Regional Distribution of Potassium in the B Horizon Clay of Some Prairie Loess Soils of the Midwest

Abstract

To test the hypothesis that K content of Iowa soils was related to soil development, samples from the B horizon of selected sites were obtained from loess‐derived prairie soils at several locations within the state. Samples were also obtained from Nebraska and Illinois loess soils to relate the Iowa study to the midwestern prairie region. Total K in clay from the B horizons decreased progressively from west to east. This was explained on the basis of concurrent increase in average annual precipitation from west to east across the area. No consistent relationships between total K content and standard indexes of profile development were obtained. However, K was highly correlated with depth to the B horizon. Although montmorillonite was the dominant clay mineral in all samples, there was relatively more illite in samples of higher K content and from sites receiving lesser amounts of annual precipitation. Studies of K released to sodium tetraphenyl boron (NaTPB) on Iowa soils reflect the trends in total K content found in the B horizons.

Subsoil Potassium in Central Iowa Soils: Status and Future Challenges

“…Regional variation in soil total K content occurs in Iowa. Soils in southern and western Iowa have higher total K content than soils in eastern Iowa (Wells and Riecken, 1969). Much of the available Iowa soil profile K data are from the pioneering work of Hanway and others (Hanway, 1961, 1962; Hanway and Scott, 1957).…”

The Potassium Status of Six Loessial Soils of Canterbury, New Zealand, in Relation to Rainfall and Rate of Loess Accumulation

“…In an average year profi P es in the low rainfall sequence late chemical weathering and leaching intensifies this i y removing the POTASSIUM STATUS O F SIX LOESSIAL SOILS than weathering intensity in the release of K and, hence, ultimately soil K status. Jackson (1964)~ Wells and Riecken (1969), and Somasiri et al (1971) have indicated that pedogenic processes are sensitively reflected in the quantity and nature of the clay fraction. But in this weakly weathering zone the quantity of clay is determined chiefly by depositional traits, and only the type of clay reflects the pedogenic influences.…”

Corn seedling response to silicon amendments in three Iowa and one Chinese soil

“…Feldsparas microcline ("K-feldspar") or plagioclase ("Ca-feldspar") comprise 10 to 20% of the sand and silt fractions, with plagioclase contents being fairly variable. For the Fayette and Ida profiles the amounts and distribution of quartz and feldspars are explained by Wells and Riecken (1969) as reflecting more intense pedological weathering of loess in eastern Iowa (where Fayette is located) than in western Iowa (where Ida is located). The more intense weathering in eastern Iowa is the result of higher rainfall causing more intense leaching and supporting forest vegetation (Wells and Riecken, 1969;Ruhe, 1984;Muhs et al, 2001).…”

“….2 Semiquantitative percentages of size fractionated silicate mineralogy with depth for the Harps, Ida and Fayette series based upon interpolation, extrapolation and interpretation of mineralogy given for Iowa soils in Khan (1991), Wells (1963), Wells and Riecken (1969), Ruhe (1984) and USDA-NRCS KSSL database (2015). ............................................................... Table 3.3 Silicate minerals identified in Iowa soils by Khan (1991), Wells and Riecken (1969) and Ruhe (1984) Table 3.4 Semiquantitative Si content partitioned by size fraction and with depth for Harps, Fayette and Ida soil series of Iowa. Contents calculated using data and information provided in Tables 3.1 through 3.3.…”