Potassium retention characteristics of a typic hydrandept from the Island of Hawaii
作者:
J. P. Ndiaye,
R. S. Yost,
期刊:
Communications in Soil Science and Plant Analysis
(Taylor Available online 1989)
卷期:
Volume 20,
issue 15-16
页码: 1601-1614
ISSN:0010-3624
年代: 1989
DOI:10.1080/00103628909368170
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Potassium‐retention characteristics of the topsoil and subsoil of a medial over thixotropic, isomesic, Typic Hydrandept (Puaulu series) was investigated under moist conditions. This soil occurs in high rainfall areas where important losses of K are likely. Exchangeable cations were extracted with 1M NH4OAc pH 7 and Potassium Retention (Kr) was calculated by the difference between initial K (exchangeable, soluble, and added K) and final K. The results indicated that for any given K solution concentration, the amount of K held by the subsoil was twice that retained by the topsoil. The relationship between Kr and Potassium Adsorption Ratio (PAR) was nonlinear. The Gapon selectivity coefficient (KG) sharply decreased with increasing Potassium Saturation (Ep) and then leveled off to an almost constant value at Ep values of 0.25 for the topsoil and 0.15 (mmol‐1L)½for the subsoil. This constant value of =KGwas reached when 5 and 10% of the initial exchange sites were occupied by K retained in the topsoil and subsoil, respectively.
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