Spatial patterns of soil nitrate in Japanese forested watersheds: importance of the near-stream zone as a source of nitrate in stream water
✍ Scribed by Kiyokazu Ohrui; Myron J. Mitchell
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 204 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0885-6087
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✦ Synopsis
Spatial patterns of N dynamics in soil were evaluated within two small forested watersheds in Japan. These two watersheds were characterized by steep slopes (4308) and high stream NO À 3 drainage rates (8 . 4 to 25 . 1 kg N ha 71 yr 71 ) that were greater than bulk precipitation N input rates (7 . 5 to 13 . 5 kg N ha 71 yr 71 ). Higher rates of nitri®cation potential at near-stream zones were re¯ected in greater NO À 3 contents for soil at the near-stream zones compared with ridge zones. Both stream discharge rates and NO À 3 concentrations in deep unsaturated soil at the near-stream zones were positively correlated to NO À 3 concentrations in stream water. These relationships, together with high soil NO À 3 contents at the near-stream zones, suggest that the nearstream zone was an important source of NO À 3 to stream water. Nitrate ¯ux from these near-stream zones was also related to the drainage of cations (K , Ca 2 and Mg 2 ). The steep slope of the watersheds resulted in small saturated areas that contributed to the high NO À 3 production (high nitri®cation rates) in the near-stream zone.