Lumbanraja, Jamalam and Evangelou, V.P. (1990) Binary and Ternary Exchange Behavior of Potassium and Ammonium on Kentucky Subsoils. Soil Science Society American Journal, 54. pp. 698-705. ISSN 0361-5995

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Potassium-Ca and NH4-Ca exchange reactions in soils are often investigated in laboratory-type studies. In these studies, it is assumed that the results from the binary exchange systems can be extrapolated to ternary (three ion) exchange systems using appropriate models. This, however, is rarely evaluated. This study deals with K-Ca exchange in the presence and absence of added NH4 and NHj-Ca exchange in the presence and absence of added K on the subsoil of three Kentucky soils, Eden clay loam (fine, mixed mesic Typic Hapludalf). Lowell clay loam (fine, mixed, mesic Typic Hapludalf), and Nicholson silt loam (fine-silly, mixed, mesic Typic Fragiudalf). The experimental approach is based on the quantity/intensity concept in order to make the findings relevant to field conditions. The added NH4 decreased the linear potential buffering capacity for the K (PBCK) more than expected and increased the equilibrium activity ratio of K (AR£) more than expected. The addition of K stimulated the adsorption of NH4 on high-affinity sites. Added NH4 induced expansion, rather than collapse, of the vermiculitic interlayer. This suggests that the NH4 was not occluded or trapped, but rather specifically adsorbed in the vermiculitic interlayer. In essence, the added NH4 permits a greater fraction of the total surface charge to be available for exchanging cations due to the interlayer expansion. The soil that demonstrated the greatest potential for specific adsorption of NH4 was the Eden, followed by the Lowell and the Nicholson. The same order exists with respect to intensity of interlayer expansion. The above suggest that the simultaneous addition of K and NH4 in soil systems may influence the fate of NH4, such as, for example, the quantities leached as NH4,volatilized as NH3, and oxidized to NO3.

Item Type: Article
Subjects: S Agriculture > S Agriculture (General)
Divisions: Fakultas Pertanian (FP) > Prodi Ilmu Tanah
Depositing User: Prof.Dr.Ir Jamalam Lumbanraja
Date Deposited: 01 Nov 2016 04:12
Last Modified: 01 Nov 2016 04:12

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