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| Titel |
Assessing winter cover crop nutrient uptake efficiency using a water quality simulation model |
| VerfasserIn |
I.-Y. Yeo, S. Lee, A. M. Sadeghi, P. C. Beeson, W. D. Hively, G. W. McCarty, M. W. Lang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 12 ; Nr. 18, no. 12 (2014-12-16), S.5239-5253 |
| Datensatznummer |
250120567
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| Publikation (Nr.) |
 copernicus.org/hess-18-5239-2014.pdf |
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| Zusammenfassung |
| Winter cover crops are an effective conservation management practice with
potential to improve water quality. Throughout the Chesapeake Bay watershed
(CBW), which is located in the mid-Atlantic US, winter cover crop use has
been emphasized, and federal and state cost-share programs are available to
farmers to subsidize the cost of cover crop establishment. The objective of
this study was to assess the long-term effect of planting winter cover crops
to improve water quality at the watershed scale (~ 50 km2) and
to identify critical source areas of high nitrate export. A
physically based watershed simulation model, Soil and Water Assessment Tool
(SWAT), was calibrated and validated using water quality monitoring data to
simulate hydrological processes and agricultural nutrient cycling over the
period of 1990–2000. To accurately simulate winter cover crop biomass in
relation to growing conditions, a new approach was developed to further
calibrate plant growth parameters that control the leaf area development
curve using multitemporal satellite-based measurements of species-specific
winter cover crop performance. Multiple SWAT scenarios were developed to
obtain baseline information on nitrate loading without winter cover crops
and to investigate how nitrate loading could change under different winter
cover crop planting scenarios, including different species, planting dates,
and implementation areas. The simulation results indicate that winter cover
crops have a negligible impact on the water budget but significantly reduce
nitrate leaching to groundwater and delivery to the waterways. Without
winter cover crops, annual nitrate loading from agricultural lands was
approximately 14 kg ha−1, but decreased to 4.6–10.1 kg ha−1 with cover crops
resulting in a reduction rate of 27–67% at the watershed scale. Rye was
the most effective species, with a potential to reduce nitrate leaching by
up to 93% with early planting at the field scale. Early planting of
cover crops (~ 30 days of additional growing days) was
crucial, as it lowered nitrate export by an additional ~ 2 kg ha−1
when compared to late planting scenarios. The effectiveness of cover
cropping increased with increasing extent of cover crop implementation.
Agricultural fields with well-drained soils and those that were more
frequently used to grow corn had a higher potential for nitrate leaching and
export to the waterways. This study supports the effective implementation of
cover crop programs, in part by helping to target critical pollution source
areas for cover crop implementation. |
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