 |
| Titel |
Regional variations in diffuse nitrogen losses from agriculture in the Nordic and Baltic regions |
| VerfasserIn |
N. Vagstad, P. Stålnacke, H.-E. Andersen, J. Deelstra, V. Jansons, K. Kyllmar, E. Loigu, S. Rekolainen, R. Tumas |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 8, no. 4 ; Nr. 8, no. 4, S.651-662 |
| Datensatznummer |
250005722
|
| Publikation (Nr.) |
 copernicus.org/hess-8-651-2004.pdf |
|
|
|
|
|
| Zusammenfassung |
| This paper describes nitrogen losses from, and the characteristics
of, 35 selected catchments (12 to 2000 ha) in the Nordic and Baltic countries.
Average annual losses of N in 1994–1997 ranged from 5 to 75 kg ha-1,
generally highest and characterised by significant within-country and interannual
variations, in Norway and the lowest losses were observed in the Baltic countries.
An important finding of the study is that the average nutrient losses varied
greatly among the studied catchments. The main explanations for this variability
were water runoff, fertiliser use (especially the amount of manure), soil type
and erosion (including stream bank erosion). However, there were several exceptions,
and it was difficult to find general relationships between the individual factors.
For example, there was poor correlation between nitrogen losses and surpluses.
Therefore, the results suggest that the observed variability in N losses cannot
have been due solely to differences in farm management practices, although the
studied catchments do include a wide range of nutrient application levels, animal
densities and other relevant elements. There is considerable spatial variation
in the physical properties (soil, climate, hydrology, and topography) and the
agricultural management of the basins, and the interaction between and relative
effects of these factors has an important impact on erosion and nutrient losses.
In particular, hydrological processes may have a marked effect on N losses measured
in the catchment stream water. The results indicate that significant differences
in hydrological pathways (e.g. the relationship between fast- and slow-flow
processes) lead to major regional differences in N inputs to surface waters
and therefore also in the response to changes in field management practices.
Agricultural practices such as crop rotation systems, nutrient inputs and soil
conservation measures obviously play a significant role in the site-specific
effects, although they cannot explain the large regional differences observed
in this study. The interactions between agricultural practices and basic catchment
characteristics, including hydrological processes, determine the final losses
of nitrogen to surface waters, hence it is necessary to understand these interactions
to manage diffuse losses of agricultural nutrients efficiently.
Keywords: agriculture, catchments, diffuse sources, nitrogen, losses, Baltic, Nordic |
| |
|
| Teil von |
|
|
|
|
|
|
|
|