Agricultural Productivity and Water Quality Tradeoffs of Winter Cover Crops at a Landscape Scale Through the Lens of Remote Sensing

2021 ◽  
Author(s):  
Kushal KC ◽  
Sami Khanal
2014 ◽  
Vol 18 (12) ◽  
pp. 5239-5253 ◽  
Author(s):  
I.-Y. Yeo ◽  
S. Lee ◽  
A. M. Sadeghi ◽  
P. C. Beeson ◽  
W. D. Hively ◽  
...  

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 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.


2001 ◽  
Vol 32 (7-8) ◽  
pp. 1221-1250 ◽  
Author(s):  
S. M. Dabney ◽  
J. A. Delgado ◽  
D. W. Reeves

2013 ◽  
Vol 10 (11) ◽  
pp. 14229-14263 ◽  
Author(s):  
I.-Y. Yeo ◽  
S. Lee ◽  
A. M. Sadeghi ◽  
P. C. Beeson ◽  
W. D. Hively ◽  
...  

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.


2021 ◽  
Vol 13 (10) ◽  
pp. 1998
Author(s):  
Mallory Liebl Barnes ◽  
Landon Yoder ◽  
Mahsa Khodaee

Cover crops are an increasingly popular practice to improve agroecosystem resilience to climate change, pests, and other stressors. Despite their importance for climate mitigation and soil health, there remains an urgent need for methods that link winter cover crops with regional-scale climate mitigation and adaptation potential. Remote sensing is ideally suited to provide these linkages, yet, cover cropping has not been analyzed extensively in remote sensing research. Methods used for remote sensing of crops from satellites traditionally leverage the difference between visible and near-infrared reflectance to isolate the signal of photosynthetically active vegetation. However, using traditional greenness indices like the Normalized Difference Vegetation Index (NDVI) for remotely sensing winter vegetation, such as winter cover crops, is challenging because vegetation reflectance signals are often confounded with reflectance of bare soil and crop residues. Here, we present new and established methods of detecting winter cover crops using remote sensing observations. We find that remote sensing methods that incorporate thermal data in addition to traditional reflectance metrics are best able to distinguish between winter farm management practices. We conclude by addressing the potential of existing and upcoming hyperspectral and thermal missions to further assess agroecosystem function in the context of global change.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 476d-476
Author(s):  
Gary R. Cline ◽  
Anthony F. Silvernail

A split-plot factorial experiment examined effects of tillage and winter cover crops on sweet corn in 1997. Main plots received tillage or no tillage. Cover crops consisted of hairy vetch, winter rye, or a mix, and N treatments consisted of plus or minus N fertilization. Following watermelon not receiving inorganic N, vetch, and mix cover cropsproduced total N yields of ≈90 kg/ha that were more than four times greater than those obtained with rye. However, vetch dry weight yields (2.7 mg/ha) were only about 60% of those obtained in previous years due to winter kill. Following rye winter cover crops, addition of ammonium nitrate to corn greatly increased (P < 0.05) corn yields and foliar N concentrations compared to treatments not receiving N. Following vetch, corn yields obtained in tilled treatments without N fertilization equaled those obtained with N fertilization. However, yields obtained from unfertilized no-till treatments were significantly (P < 0.05) lower than yields of N-fertilized treatments. Available soil N was significantly (P < 0.05) greater following vetch compared to rye after corn planting. No significant effects of tillage on sweet corn plant densities or yields were detected. It was concluded that no-tillage sweet corn was successful, and N fixed by vetch was able to sustain sweet corn production in tilled treatments but not in no-till treatments.In previous years normal, higher-yielding vetch cover crops were able to sustain sweet corn in both tilled and no-till treatments.


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