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M. W. Lang - One of the best experts on this subject based on the ideXlab platform.
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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences, 2014Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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 km 2 ) 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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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences Discussions, 2013Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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.
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using satellite remote sensing to estimate winter Cover Crop nutrient uptake efficiency
Journal of Soil and Water Conservation, 2009Co-Authors: W. Dean Hively, M. W. Lang, Gregory W. Mccarty, A. M. Sadeghi, Jason Keppler, Laura L McconnellAbstract:Winter Cover Crops are recognized as an important agricultural conservation prac- tice for reducing nitrogen (N) losses to groundwater following the summer growing season. Accordingly, cost-share programs have been established to promote winter Cover Crops for water quality on farms throughout the Chesapeake Bay watershed. However, current esti- mates of Cover Crop nutrient uptake are largely calculated from plot-scale studies extrapolated to watershed-scale based solely on enrollment acreage. Remote sensing provides a tool for rapid estimation of Cover Crop biomass production on working farms throughout the land- scape. This project combined cost-share program enrollment data with satellite imagery and on-farm sampling to evaluate Cover Crop N uptake on 136 fields within the Choptank River watershed, on Maryland's eastern shore. The Normalized Difference Vegetation Index was a successful predictor of aboveground biomass for fields with >210 kg ha -1 (>187 lb ac -1 ) of vegetation (corresponding to 4.2 kg ha -1 (3.7 lb ac -1 ) of plant N ), below which the back- ground reflectance of soils and Crop residues obstructed the Cover Crop signal. Cover Crops planted in the two weeks prior to the regional average first frost date (October 15) exhibited average fall aboveground N uptake rates of 18, 13, and 5 kg ha -1 (16, 12, 4 lb ac -1 ) for rye, barley, and wheat, respectively, corresponding to 1,260, 725, and 311 kg ha -1 (1,124, 647, 277 lb ac -1 ) of aboveground biomass, with associated cost-share implementation costs of $5.49, $7.60, and $19.77 kg -1 N ($2.50, $3.46, and $8.99 lb -1 N). Cover Crops planted after October 15 exhibited significantly reduced biomass and nutrient uptake, with associated program costs of $15.44 to $20.59 kg -1 N ($7.02 to $9.36 lb -1 N). Agronomic factors influencing Cover Crop performance included species, planting date, planting method, and previous Crop. Field sam- pling locations with >1,000 kg ha -1 (>890 lb ac -1 ) of springtime Cover Crop biomass exhibited greatly reduced soil nitrate (<3 mg kg -1 (<3 ppm)) in comparison to fields with low Cover Crop biomass (up to 14 mg kg -1 soil nitrate), indicating a target biomass threshold for maxi- mum water quality impact. Additional sampling years will be necessary to account for Cover Crop response to climate variability. Combining remote sensing with farm program data can provide important information to scientists and regulators working to improve conservation programs. Results can be used to more effectively utilize scarce conservation resources and increase water quality protection.
A. M. Sadeghi - One of the best experts on this subject based on the ideXlab platform.
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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences, 2014Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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 km 2 ) 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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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences Discussions, 2013Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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.
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using satellite remote sensing to estimate winter Cover Crop nutrient uptake efficiency
Journal of Soil and Water Conservation, 2009Co-Authors: W. Dean Hively, M. W. Lang, Gregory W. Mccarty, A. M. Sadeghi, Jason Keppler, Laura L McconnellAbstract:Winter Cover Crops are recognized as an important agricultural conservation prac- tice for reducing nitrogen (N) losses to groundwater following the summer growing season. Accordingly, cost-share programs have been established to promote winter Cover Crops for water quality on farms throughout the Chesapeake Bay watershed. However, current esti- mates of Cover Crop nutrient uptake are largely calculated from plot-scale studies extrapolated to watershed-scale based solely on enrollment acreage. Remote sensing provides a tool for rapid estimation of Cover Crop biomass production on working farms throughout the land- scape. This project combined cost-share program enrollment data with satellite imagery and on-farm sampling to evaluate Cover Crop N uptake on 136 fields within the Choptank River watershed, on Maryland's eastern shore. The Normalized Difference Vegetation Index was a successful predictor of aboveground biomass for fields with >210 kg ha -1 (>187 lb ac -1 ) of vegetation (corresponding to 4.2 kg ha -1 (3.7 lb ac -1 ) of plant N ), below which the back- ground reflectance of soils and Crop residues obstructed the Cover Crop signal. Cover Crops planted in the two weeks prior to the regional average first frost date (October 15) exhibited average fall aboveground N uptake rates of 18, 13, and 5 kg ha -1 (16, 12, 4 lb ac -1 ) for rye, barley, and wheat, respectively, corresponding to 1,260, 725, and 311 kg ha -1 (1,124, 647, 277 lb ac -1 ) of aboveground biomass, with associated cost-share implementation costs of $5.49, $7.60, and $19.77 kg -1 N ($2.50, $3.46, and $8.99 lb -1 N). Cover Crops planted after October 15 exhibited significantly reduced biomass and nutrient uptake, with associated program costs of $15.44 to $20.59 kg -1 N ($7.02 to $9.36 lb -1 N). Agronomic factors influencing Cover Crop performance included species, planting date, planting method, and previous Crop. Field sam- pling locations with >1,000 kg ha -1 (>890 lb ac -1 ) of springtime Cover Crop biomass exhibited greatly reduced soil nitrate (<3 mg kg -1 (<3 ppm)) in comparison to fields with low Cover Crop biomass (up to 14 mg kg -1 soil nitrate), indicating a target biomass threshold for maxi- mum water quality impact. Additional sampling years will be necessary to account for Cover Crop response to climate variability. Combining remote sensing with farm program data can provide important information to scientists and regulators working to improve conservation programs. Results can be used to more effectively utilize scarce conservation resources and increase water quality protection.
Jason P Kaye - One of the best experts on this subject based on the ideXlab platform.
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Cover Crop species affect mycorrhizae-mediated nutrient uptake and pest resistance in maize
Renewable Agriculture and Food Systems, 2019Co-Authors: Ebony G. Murrell, Swayamjit Ray, Mary E. Lemmon, Dawn S. Luthe, Jason P KayeAbstract:AbstractArbuscular mycorrhizal fungi (AMF) can increase plant nutrient uptake and chemical defense production, both of which can improve plants’ ability to resist insect herbivory. Cover Crops—non-commercial species planted in between cash Crops in a Crop rotation—can naturally alter both soil nutrients and AMF. We tested whether different Cover Crop species alter AMF colonization, plant nutrient status and plant–insect interactions in a subsequent maize Crop. Cover Crop species were either non-mycorrhizal, non-leguminous (canola, forage radish), mycorrhizal non-leguminous (cereal rye, oats), mycorrhizal leguminous (clover, pea) or absent (fallow). We measured the cascading consequences of Cover Crop treatment on maize root AMF colonization, maize growth and performance of an herbivorous insect (European corn borer) feeding on the maize. Maize AMF colonization was greater in plots previously planted with mycorrhizal (rye, oats) than non-mycorrhizal (canola, radish) Cover Crops or no Cover Crop (fallow). AMF colonization was linked to increased plant phosphorous and nitrogen, and maize growth increased with low plant N:P. Induced jasmonic acid pathway plant defenses increased with increasing maize growth and AMF colonization. European corn borer survivorship decreased with lower plant N:P, and insect development rate decreased with increased induced plant defenses. Our data describe a cascade in which Cover Crop species selection can increase or decrease mycorrhizal colonization of subsequent maize Crop roots, which in turn impacts phosphorus uptake and may affect herbivory resistance in the maize. These results suggest that farmers could select Cover Crop species to manage nutrient uptake and pest resistance, in order to amend or limit fertilizer and pesticide use.
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growing degree days and Cover Crop type explain weed biomass in winter Cover Crops
Agronomy for Sustainable Development, 2018Co-Authors: Barbara Baraibar, Mitchell C Hunter, Denise M Finney, William S Curran, Jess M Bunchek, Jason P Kaye, David A Mortensen, Mary E Barbercheck, Charles M WhiteAbstract:Cover Crops are increasingly being adopted to provide multiple ecosystem services, including weed suppression. Understanding what drives weed biomass in Cover Crops can help growers make the appropriate management decisions to effectively limit weed pressure. In this paper, we use a unique dataset of 1764 measurements from seven Cover Crop research experiments in Pennsylvania (USA) to predict, for the first time, weed biomass in winter Cover Crops in the fall and spring. We assessed the following predictors: Cover Crop biomass in the fall and spring, fall and spring growing degree days between planting and Cover Crop termination, Cover Crop type (grass, brassica, legume monocultures, and mixtures), system management (organic, conventional), and tillage before Cover Crop seeding (no-till, tillage). We used random forests to develop the predictive models and identify the most important variables explaining weed biomass in Cover Crops. Growing degree days, Cover Crop type, and Cover Crop biomass were the most important predictor variables in both the fall (r2 = 0.65) and spring (r2 = 0.47). In the fall, weed biomass increased as accumulated growing degree days increased, which was mainly related to early planting dates. Fall weed biomass was greater in legume and brassica monocultures compared to grass monocultures and mixtures. Cover Crop and weed biomass were positively correlated in the fall, as early planting of Cover Crops led to high Cover Crop biomass but also to high weed biomass. In contrast, high spring Cover Crop biomass suppressed weeds, especially as spring growing degree days increased. Grass and brassica monocultures and mixtures were more weed-suppressive than legumes. This study is the first to be able to predict weed biomass in winter Cover Crops using a random forest approach. Results show that weed suppression by winter Cover Crops can be enhanced with optimal Cover Crop species selection and seeding time.
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functional diversity in Cover Crop polycultures increases multifunctionality of an agricultural system
Journal of Applied Ecology, 2017Co-Authors: Denise M Finney, Jason P KayeAbstract:Summary Ecological studies identifying a positive relationship between biodiversity and ecosystem services motivate projections that higher plant diversity will increase services from agroecosystems. While this idea is compelling, evidence of generalizable relationships between biodiversity and ecosystem services that could be broadly applied in agricultural systems is lacking. Cover Crops grown in rotation with cash Crops are a realistic strategy to increase agroecosystem diversity. We evaluated the prediction that further increasing diversity with Cover Crop polycultures would enhance ecosystem services and multifunctionality in a 2-year study of eighteen Cover Crop treatments ranging in diversity from one to eight species. Five ecosystem services were measured in each Cover Crop system and regression analysis used to explore the relationship between multifunctionality and several diversity indices. As expected, there was a positive relationship between species richness and multifunctionality, but it only explained a small fraction of variance in ecosystem services (marginal R2 = 0·05). In contrast, indices of functional diversity, particularly the distribution of trait abundances, were stronger predictors of multifunctionality (marginal R2 = 0·15–0·38). Synthesis and application. In a corn production system, simply increasing Cover Crop species richness will have a small impact on agroecosystem services, but designing polycultures that maximize functional diversity may lead to agroecosystems with greater multifunctionality.
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managing the trade off between nitrogen supply and retention with Cover Crop mixtures
Agriculture Ecosystems & Environment, 2017Co-Authors: Charles White, Denise M Finney, Tianna S Dupont, Mena Hautau, Dave Hartman, Brosi Bradley, James C Lachance, Jason P KayeAbstract:Abstract The ability of Cover Crop mixtures to provide both nitrogen (N) retention and N supply services has been extensively studied in research station experiments, especially with grass-legume bicultures. Mixtures are often as effective as grass monocultures at N retention, but the N supply service can be compromised when non-legumes dilute the presence of legumes in a Cover Crop stand. To study the tradeoffs between N retention and supply when using Cover Crop mixtures, we measured N retention and supply in distributed on-farm experiments, developed multiple linear regression models to predict N retention and supply based on Cover Crop functional characteristics and environmental variables, and synthesized the regression models into a graphical analysis tool. The experiments took place on three organic farms and a research station in Pennsylvania, USA and tested 3-species and 4-species Cover Crop mixtures in comparison to commonly used grass and legume monocultures. Cover Crop treatments were planted between a small grain Crop harvested in mid-summer and a maize ( Zea mays L.) Crop planted the following spring. Potential nitrate (NO 3 − ) leaching below 30 cm, an indicator of the N retention service, declined as the presence of non-legume species in a Cover Crop increased ( r 2 = 0.72). Potential NO 3 − leaching increased as the August soil NO 3 − -N concentration increased and as the fall biomass N content of winter-killed species or canola ( Brassica napus L. ‘Wichita’) increased. Relative maize yield, an indicator of the N supply service, decreased as fall and spring Cover Crop biomass carbon-to-nitrogen (C:N) ratios increased and increased as total spring biomass N content and soil carbon (C) concentration increased (r 2 = 0.56). Synthesizing the regression models in a graphical analysis tool revealed a tradeoff between N supply and retention services for Cover Crop mixtures, where increasing the fractional non-legume seeding rate to reduce potential NO 3 − leaching also reduced relative maize yield. The tradeoff could be minimized by managing environmental conditions and Cover Crop composition so that potential NO 3 − leaching remains low even when the fractional non-legume seeding rate is low. The regression models suggest this could be achieved by maintaining low soil NO 3 − -N concentrations prior to Cover Crop planting in August, not including winter-killed legumes in the mixture, and using non-legume species that are the most efficient at N retention. Thus, with thoughtful management of Cover Crops and soils, farmers may be able to realize the potential of Cover Crop mixtures to provide high levels of both N retention and supply services.
W. Dean Hively - One of the best experts on this subject based on the ideXlab platform.
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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences, 2014Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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 km 2 ) 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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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences Discussions, 2013Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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.
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using satellite remote sensing to estimate winter Cover Crop nutrient uptake efficiency
Journal of Soil and Water Conservation, 2009Co-Authors: W. Dean Hively, M. W. Lang, Gregory W. Mccarty, A. M. Sadeghi, Jason Keppler, Laura L McconnellAbstract:Winter Cover Crops are recognized as an important agricultural conservation prac- tice for reducing nitrogen (N) losses to groundwater following the summer growing season. Accordingly, cost-share programs have been established to promote winter Cover Crops for water quality on farms throughout the Chesapeake Bay watershed. However, current esti- mates of Cover Crop nutrient uptake are largely calculated from plot-scale studies extrapolated to watershed-scale based solely on enrollment acreage. Remote sensing provides a tool for rapid estimation of Cover Crop biomass production on working farms throughout the land- scape. This project combined cost-share program enrollment data with satellite imagery and on-farm sampling to evaluate Cover Crop N uptake on 136 fields within the Choptank River watershed, on Maryland's eastern shore. The Normalized Difference Vegetation Index was a successful predictor of aboveground biomass for fields with >210 kg ha -1 (>187 lb ac -1 ) of vegetation (corresponding to 4.2 kg ha -1 (3.7 lb ac -1 ) of plant N ), below which the back- ground reflectance of soils and Crop residues obstructed the Cover Crop signal. Cover Crops planted in the two weeks prior to the regional average first frost date (October 15) exhibited average fall aboveground N uptake rates of 18, 13, and 5 kg ha -1 (16, 12, 4 lb ac -1 ) for rye, barley, and wheat, respectively, corresponding to 1,260, 725, and 311 kg ha -1 (1,124, 647, 277 lb ac -1 ) of aboveground biomass, with associated cost-share implementation costs of $5.49, $7.60, and $19.77 kg -1 N ($2.50, $3.46, and $8.99 lb -1 N). Cover Crops planted after October 15 exhibited significantly reduced biomass and nutrient uptake, with associated program costs of $15.44 to $20.59 kg -1 N ($7.02 to $9.36 lb -1 N). Agronomic factors influencing Cover Crop performance included species, planting date, planting method, and previous Crop. Field sam- pling locations with >1,000 kg ha -1 (>890 lb ac -1 ) of springtime Cover Crop biomass exhibited greatly reduced soil nitrate (<3 mg kg -1 (<3 ppm)) in comparison to fields with low Cover Crop biomass (up to 14 mg kg -1 soil nitrate), indicating a target biomass threshold for maxi- mum water quality impact. Additional sampling years will be necessary to account for Cover Crop response to climate variability. Combining remote sensing with farm program data can provide important information to scientists and regulators working to improve conservation programs. Results can be used to more effectively utilize scarce conservation resources and increase water quality protection.
Gregory W. Mccarty - One of the best experts on this subject based on the ideXlab platform.
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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences, 2014Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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 km 2 ) 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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Assessing winter Cover Crop nutrient uptake efficiency using a water quality simulation model
Hydrology and Earth System Sciences Discussions, 2013Co-Authors: A. M. Sadeghi, Peter C. Beeson, W. Dean Hively, Gregory W. Mccarty, M. W. LangAbstract: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.
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using satellite remote sensing to estimate winter Cover Crop nutrient uptake efficiency
Journal of Soil and Water Conservation, 2009Co-Authors: W. Dean Hively, M. W. Lang, Gregory W. Mccarty, A. M. Sadeghi, Jason Keppler, Laura L McconnellAbstract:Winter Cover Crops are recognized as an important agricultural conservation prac- tice for reducing nitrogen (N) losses to groundwater following the summer growing season. Accordingly, cost-share programs have been established to promote winter Cover Crops for water quality on farms throughout the Chesapeake Bay watershed. However, current esti- mates of Cover Crop nutrient uptake are largely calculated from plot-scale studies extrapolated to watershed-scale based solely on enrollment acreage. Remote sensing provides a tool for rapid estimation of Cover Crop biomass production on working farms throughout the land- scape. This project combined cost-share program enrollment data with satellite imagery and on-farm sampling to evaluate Cover Crop N uptake on 136 fields within the Choptank River watershed, on Maryland's eastern shore. The Normalized Difference Vegetation Index was a successful predictor of aboveground biomass for fields with >210 kg ha -1 (>187 lb ac -1 ) of vegetation (corresponding to 4.2 kg ha -1 (3.7 lb ac -1 ) of plant N ), below which the back- ground reflectance of soils and Crop residues obstructed the Cover Crop signal. Cover Crops planted in the two weeks prior to the regional average first frost date (October 15) exhibited average fall aboveground N uptake rates of 18, 13, and 5 kg ha -1 (16, 12, 4 lb ac -1 ) for rye, barley, and wheat, respectively, corresponding to 1,260, 725, and 311 kg ha -1 (1,124, 647, 277 lb ac -1 ) of aboveground biomass, with associated cost-share implementation costs of $5.49, $7.60, and $19.77 kg -1 N ($2.50, $3.46, and $8.99 lb -1 N). Cover Crops planted after October 15 exhibited significantly reduced biomass and nutrient uptake, with associated program costs of $15.44 to $20.59 kg -1 N ($7.02 to $9.36 lb -1 N). Agronomic factors influencing Cover Crop performance included species, planting date, planting method, and previous Crop. Field sam- pling locations with >1,000 kg ha -1 (>890 lb ac -1 ) of springtime Cover Crop biomass exhibited greatly reduced soil nitrate (<3 mg kg -1 (<3 ppm)) in comparison to fields with low Cover Crop biomass (up to 14 mg kg -1 soil nitrate), indicating a target biomass threshold for maxi- mum water quality impact. Additional sampling years will be necessary to account for Cover Crop response to climate variability. Combining remote sensing with farm program data can provide important information to scientists and regulators working to improve conservation programs. Results can be used to more effectively utilize scarce conservation resources and increase water quality protection.
