Assessing winter cover crop nutrient uptake efficiency using a water quality simulation model

Hydrology and Earth System Sciences
Department of Geographical Sciences, University of Maryland, College Park, MD; USDA-ARS, Hydrology and Remote Sensing Laboratory, Beltsville, MD; Dream it Do it Western New York, Jamestown, NY; USDA Forest Service, Northern Research Station, Beltsville, MD
By: , and 

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Abstract

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 winter cover crop establishment. The objective of this study was to assess the long-term effect of planting winter cover crops at the watershed scale 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 and satellite-based estimates of winter cover crop species performance to simulate hydrological processes and nutrient cycling over the period of 1991–2000. Multiple scenarios were developed to obtain baseline information on nitrate loading without winter cover crops planted and to investigate how nitrate loading could change with different winter cover crop planting scenarios, including different species, planting times, and implementation areas. The results indicate that winter cover crops had a negligible impact on water budget, but significantly reduced nitrate leaching to groundwater and delivery to the waterways. Without winter cover crops, annual nitrate loading was approximately 14 kg ha−1, but it decreased to 4.6–10.1 kg ha−1 with winter cover crops resulting in a reduction rate of 27–67% at the watershed scale. Rye was most effective, with a potential to reduce nitrate leaching by up to 93% with early planting at the field scale. Early planting of winter 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 winter 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 implement of winter cover crop programs, in part by helping to target critical pollution source areas for winter cover crop implementation.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Assessing winter cover crop nutrient uptake efficiency using a water quality simulation model
Series title Hydrology and Earth System Sciences
DOI 10.5194/hessd-10-14229-2013
Volume 10
Issue 11
Year Published 2013
Language English
Publisher European Geosciences Union
Contributing office(s) Eastern Geographic Science Center
Description 35 p.
First page 14229
Last page 14263
Country United States
Other Geospatial Chesapeake Bay Watershed
Online Only (Y/N) N
Additional Online Files (Y/N) N