Effect of Potassium on Soil Structure in Relation to Hydraulic Conductivity

Y. Chen*, A. Banin, A. Borochovitch

*Corresponding author for this work

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5 Scopus citations

Abstract

Abstract: Chen, Y., Banin, A. and Borochovitch, A., 1983. Effect of potassium on soil structure in relation to hydraulic conductivity. Geoderma, 30: 135-147. The effect of exchangeable K+ on soil structure and permeability has been studied. A loamy sand, a light clay and a heavy clay soil were leached with solutions adjusted to potassium adsorption ratios (PAR) of 0.0, 0.72, 3.74 and ∞. Exchangeable K+ percentage (EPP) and hydraulic conductivity (HC) were measured on the leached soils. SEM observations on undisturbed soil samples were used to evaluate changes in soil structure and pore size. EPP values for the three soils ranged as follows: 0.8-1.3, 5.5-9.2, 16.0-21.0 and 58.0-76.0 for PAR's of 0.0, 0.72, 3.74 and ∞, respectively. HC increased slightly (20%) up to EPP values of about 20% for the loamy sand and heavy clay soil, while a decrease in HC corresponding to any increase of EPP was observed for the light clay soil. This soil was richer in illite and also exhibited higher affinity for K+. At the highest EPP values (58.0-76.0) HC of the three soils decreased to about 20% of the values measured for the Ca2+ saturated soils. SEM observations were performed and Ca2+ saturated soils compared with the K+ enriched ones. Ca2+ treated loamy sand exhibited discrete clay aggregates located in the spaces between sand particles or attached to them. K+ enrichment resulted in the formation of a dense network of clay microaggregates filling up the pore space. The micro-aggregate structure of the two Ca2+ clay soils changed to a dense layer composed of much smaller particles following K+ enrichment. Pores were mostly smaller than 10 μm in the K+ soil compared to several tens of microns in the Ca2+ form. SEM observations and the fact that clay content did not vary with depth suggest that dispersion of clay microaggregates and their rearrangement in situ were the major mechanisms involved in HC reduction, rather than long-range clay migration and the formation of a clay enriched layer with impeded drainage.

Original languageEnglish
Pages (from-to)135-147
Number of pages13
JournalDevelopments in Soil Science
Volume12
Issue numberC
DOIs
StatePublished - 1983

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