High nitrogen, especially ammonium, input has been observed in Shichinohe, Aomori Prefecture, northeastern Japan. The monitoring study on soil and soil solution has been carried out to determine soil acidification status since 1996. Soils and soil solutions in Minamitonai and Haginosawa are not strongly acidic. Fluctuations in nitrate concentrations coincided with sodium (Na+) or calcium (Ca2+). Produced protons due to nitrification were exchanged with Ca2+ or neutralized by weathering process. Exchangeable Ca2+ accumulated in surface layers, particular in the older Japanese cedar (Cryptomeria japonica) stand (42 years old). Exchangeable Ca2+ affected soil solution chemistry and the Ca2+ concentration was significantly higher in the older Japanese cedar stand than that in the younger stand (22 years old). Base cations, especially Ca2+, accumulation prevented soil (solution) acidification in Shichinohe site.
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- Soil Solution Chemistry in Japanese Cedar Stands in Northern Honshu, with High Nitrogen Deposition
- Springer Netherlands