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Kinetics and Mechanisms of Potassium Release from Sandy Middle Atlantic Coastal Plain Soils
Author(s) -
Sadusky M. C.,
Sparks D. L.,
Noll M. R.,
Hendricks G. J.
Publication year - 1987
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1987.03615995005100060011x
Subject(s) - loam , soil water , coastal plain , entisol , chemistry , potassium , mineralogy , geology , environmental chemistry , soil science , paleontology , organic chemistry
Kinetics of K release were investigated on a Kenansville loamy sand (loamy, siliceous, thermic Arenic Hapludults), a Rumford loamy sand (coarse‐loamy, siliceous, thermic Typic Hapludults), and a Sassafras fine sandy loam (fine‐loamy, mixed, mesic Typic Hapludults) from the Delaware Coastal Plain. Previous field experiments had shown that corn ( Zea mays L.) grown on these soils did not respond to K applications. The soils contained high levels of total K ranging from 22.5 to 46.5 cmol kg −1 . Most of the total K was in the mineral form, particularly feldspars, and was contained in the sand fractions of the soils. Kinetics of K release from the whole soils and from the coarse, medium, and fine sand fractions were studied using a H‐saturated resin and 0.01 M oxalic acid. Potassium release from the whole soils, using the resin, ranged from 0.172 to 0.251 cmol kg −1 over a 30‐d period, and significantly more K was released with the resin than with oxalic acid. The K release that occurred from the sand fractions was attributed to the highly weathered nature of the K‐feldspars in these soils as observed by electron microbeam analyses. The mechanism of K release from the soil feldspars appears to be a surface‐controlled reaction.