Pedosphere 16(2): 264--272, 2006
ISSN 1002-0160/CN 32-1315/P
©2006 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Nitrogen flow in the rural ecosystem of Mikasa City in Hokkaido, Japan |
L. LIANG1 , T. NAGUMO2 and R. HATANO1,3 |
1 Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589 (Japan). E-mail: liang@chem.agr.hokudai.ac.jp
2 Center for Education and Research of Field Sciences, Shizuoka University, Fujieda 426-0001 (Japan)
3 Field Science Center for Northern Biosphere, Hokkaido University, Sapporo 060-8589 (Japan) |
| ABSTRACT |
| This study of Mikasa City in 2001, which analyzed N flow between N production and N load in seven agricultural and settlement subsystems, i.e., paddy, onion, wheat, vegetable, dairy, chicken, and citizen subsystems, aimed to compare N flow in each subsystem, to determine the main sources of the N load, and to evaluate the influence of agricultural production and food consumption on N cycling in a rural area. The results showed that in Mikasa city, 38.5% of the N load came from point sources and the remainder from non-point sources with intensive vegetable farming imparting a serious N load. Because of the internal N cycling in the dairy subsystem, chemical fertilizer application was reduced by 70.2%, and 23.72 Mg manure N was recycled to the field; therefore, the N utilization efficiency was raised from 18.1% to 35.1%. If all the manure N in the chicken subsystem was recycled, chemical fertilizer application would be reduced by 8.1% from the present level, and the point sources of N pollution would be reduced by 20.8%. |
| Key Words: chemical fertilizers, ecosystem, environmental nitrogen load, nitrogen flow, nitrogen budget |
| Citation: Liang, L., Nagumo, T. and Hatano, R. 2006. Nitrogen flow in the rural ecosystem of Mikasa City in Hokkaido, Japan. Pedosphere. 16(2): 264-272. |
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