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Release of Potassium from Nonexchangeable Forms from Size Fractions of Several Iowea Soils
Author(s) -
Pratt P. F.
Publication year - 1952
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/sssaj1952.03615995001600010009x
Subject(s) - soil water , fractionation , silt , chemistry , fraction (chemistry) , particle size , potassium , weathering , extraction (chemistry) , solubility , mineralogy , chromatography , geology , soil science , organic chemistry , paleontology , geomorphology
Surface samples of 13 Iowa soils were fractionated into six size fractions. K release from nonexchangeable forms from these size fractions was measured by an extraction for 10 minutes with boiling 1.0 N NHO 3 . The K release to HNO 3 per unit weight was highest in the 0.2‐ to 2‐micron fraction for 12 of the 13 soils, was highest in the <0.2‐micron fraction for one soil, and decreased with increase in particle size in the silt fractions. For each of six size fractions the release per unit weight was correlated with release from the whole soil. The calculated percentage distribution of K release among the size fractions suggested that the clay fractions contributed about 60% and the coarser fractions contributed about 40% of the K release from the whole soil. For eight soils the lowest total K was in the <0.2‐micron fraction and the highest total K was in the 2‐ to 5‐micron fraction. The percentage of the total K which was soluble in HNO 3 was highest in the <0.2‐micron fraction and decreased with increase in particle size. The percentage solubility of K in the clay fraction was not related to the degree of weathering of the soils, but the percentage solubility in the silt fractions was closely correlated with degree of weathering.