Native Fixed Ammonium in Hawaiian Soils
1968
Mikami, David T. | Kanehiro, Yoshinori
Native fixed ammonium was found to range from 0 to 585 ppm. Volcanic ash soil horizons generally had a lower fixed ammonium content (4 to 178 ppm) than those from basalt (0 to 585 ppm). There was a general decrease of fixed ammonium concentration with depth in most of the profiles, this pattern of decrease being more pronounced in basaltic soils than in ash soils. Native fixed NH₄-nitrogen as a fraction of total nitrogen in individual horizons varied from 0 to 32.9%. This fraction was generally much greater in the basalt soils than in the ash soils. The soils did not show any definite pattern in the profile as to the relative amount of nitrogen present as native fixed ammonium. There was a highly significant relationship between native fixed ammonium and total K₂O and percent mica in both ash and basalt soils. This relationship, however, does not apply to young, partially weathered soils containing primary potassium-bearing minerals. The difference between organic C/organic N and organic C/total N ratios was generally greater in basaltic soils than in ash soils.
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