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Effect of Long‐term Lime and Potassium Applications on Quantity‐Intensity (Q/I) Relationships in Sandy Soil
Author(s) -
Sparks D. L.,
Liebhardt W. C.
Publication year - 1981
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/sssaj1981.03615995004500040022x
Subject(s) - lime , vermiculite , loam , potassium , chemistry , horizon , soil horizon , mineralogy , zoology , soil water , geology , soil science , mathematics , biology , paleontology , geometry , organic chemistry
The effects of long‐term lime and K applications on quantity‐intensity (Q/I) relationships were investigated on the Ap and B21t horizons of a Kalmia soil (a fine‐loamy over sandy or sandy‐skeletal, siliceous thermic (Typic Hapludults) from the Delaware Coastal Plain. The predominant mineral suite of the <2µm clay fraction was mica, vermiculite, and chloritized vermiculite. Soil pH and exchangeable bases increased with depth and with lime additions. The equilibrium potassium activity ratio (AR k e ) decreased with profile depth due to greater K fixation by specific sites for K in the B21t horizon. The AR k e decreased in the Ap horizon and increased in the B21t horizon with lime additions. The magnitude of AR k e [> 0.01 (moles/liter) ½ ] suggests that K adsorption in the Ap horizon occurred on planar positions while adsorption at specific sites was predominant in the B21t horizon [> 0.006 (moles/liter) ½ ]. The parameter δ K o , which measures labile K, became more negative with increased lime and K additions, indicating a greater K release into soil solution. While the quantity of K extracted by NH 4 OAc compared favorably to δ K o in the Ap horizon, it exceeded δ K o in the B21t horizon, suggesting K exchange involving specific sites in the B21t horizon. The number of specific sites ( K x ) increased with K fertilization and with soil depth. The decreased K x with increased lime additions could be ascribed to increased neutralization of hydroxyaluminum interlayer material, resulting in an increase in interlayer “islands.” The potential buffer capacity (PBC k ) parameter increased with lime additions due to increased pH‐dependent cation exchange capacity (CEC).