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Relationship of Ammonium Nitrogen Distribution to Mineralogy in a Hapludalf Soil
Author(s) -
Sparks D. L.,
Blevins R. L.,
Bailey H. H.,
Barnhisel R. I.
Publication year - 1979
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/sssaj1979.03615995004300040034x
Subject(s) - vermiculite , silt , ammonium , chemistry , mineralogy , nitrogen , clay minerals , soil water , calcareous , mica , geology , soil science , paleontology , organic chemistry
Distribution of fixed and exchangeable ammonium were examined in three soil profiles of the Shrouts series from the Knobs region of eastern Kentucky. Shrouts soils (fine, mixed, mesic, Typic Hapludalfs) have high base status; exhibit strong, prismatic structure; and are derived from calcareous, high magnesium, soft (weakly cemented) clay shale. Soil pH ranges from 6.3 in the Ap horizon to 7.9 in the C. Analyses, using the Silva and Bremner procedure, showed considerable fixed NH 4 + ‐N in all horizons of each profile. Mean fixed NH 4 + ‐N in the profiles was 365 ppm for the Ap, 463 ppm for the B21t, 433 ppm for the B22t, 469 ppm for the C, and 543 ppm for the Cr horizons. Exchangeable NH 4 + ‐N also increased with depth, with values being about 1.2 to 1.5% of the fixed NH 4 + ‐N values. X‐ray diffraction analyses of the clays and silts revealed predominantly mica in the 2–0.2 and <0.2 µm fractions, with some vermiculite present, and large quantities of mica in the silt fractions. High correlation ( r = 0.92) was found between fixed NH 4 + ‐N and exchangeable NH 4 + ‐N. A correlation exists between fixed NH 4 + ‐N and mica + vermiculite content with an r value of 0.68. The fixed NH 4 + ‐N in the lower horizons is presumed to be indigeous, since no NH 4 + ‐N has been added recently to the soil.