Mr. Mark Dubin, was the last speaker. The topic of his presentation was Modeling Pasture Management for Water Quality: The Chesapeake Bay Program’s Efforts for Representing Pasture BMPs. Mark is an agricultural technical coordinator with the University of Maryland Extension. He works with the USDA-NIFA Mid-Atlantic Water Program and the EPA Chesapeake Bay Program Office.
Mark started out with the background about the EPA Chesapeake Bay Program. A recent law suit brought by the Chesapeake Bay Foundation against USEPA was settled. This spurred the Obama Administration to release a strategy to protect and restore the Chesapeake Bay Watershed that sped up the efforts to control sediment, nitrogen, and phosphorus from entering Bay waters to reduce pollution loads to receiving streams that flow to the Bay. In December 2010, the Chesapeake Bay Total Maximum Daily Loads (TMDLs) were identified as the necessary limits of nitrogen, phosphorus and sediment to be found in receiving streams in Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia that flow to the Bay. This will serve as a model for TDML limits to all watersheds across the Nation.
The health of the Bay has improved since the Bay Program started, but there are still much more work to do. On the next page, is a map of the Watershed showing the health of different stream segments that flow ultimately into the Bay. The major river systems are the Susquehanna, Potomac, James, Patuxent, Rappahannock, York, the Eastern Shore streams, and the Western Shore streams. The water quality goals for the Bay of dissolved oxygen, water clarity, chlorophyll A, and chemical contaminants as a whole are only at 21% of goal. Habitat restoration and lower food web goals of Bay grasses, phytoplankton, and bottom habitat are 45% achieved as a whole. Fish and shellfish goals are a mixed bag, with blue crab restoration at 60% of goal, rockfish at 100%, but oysters are only at 9% and shad at 23%. Actually agricultural goals in achieving goals in reduction of sediment, N, and P to Bay waters was at about 50% in 2007. Meanwhile, Urban/Suburban stormwater is the only pollution source sector in the Bay watershed that is still growing. Its load is 70% higher than at the outset of the Bay Program.
The main sources of Bay pollution are:
- Agriculture: animal manure, commercial fertilizer, soil erosion,
- Urban/suburban runoff: lawn fertilizers, dog waste, uncollected leaves, soil erosion, tire rubber, oil
- Air pollution: tailpipes, power plants, nitrous oxides and ammonia from various sources
- Wastewater: sewage treatment plants, phosphorus, nitrogen, stormwater related releases
Agriculture contributes 60% of the sediment, 45% of the P, and 38% of the N (includes atmospheric deposition attributed to Ag.) going into Bay waters. Urban/suburban runoff and atmospheric deposition contributes 19% of the sediment, 31% of the P, and 30% of the N. The other sediment source is “natural” mainly from woodland acreage, this category accounts for the other 21% of sediment contributed to Bay waters. Wastewater treatment facilities contribute 21% of the P and 20% of N flowing into Bay waters.
Phase II of the Bay Watershed Implementation Plan started this year, 2011. This provides local planning targets for counties, smaller watersheds, and sources. Also beginning in 2011 are 2-year
milestones, reporting, modeling, and monitoring. By 2017, 60% of the BMP’s must be in place. Then phase III of the Watershed Implementation Plan begins to get 100% of the BMP’s in place by 2025.
Mark then moved on to pasture management modeling. Partitioning of the model is done by breaking down practices into different categories that influence runoff to surface waters. There are practices that involve land-use conversions. Here load reductions are attributed to movement to lower-exporting landuses. There are other practices with nutrient and sediment reduction efficiencies. Load reductions attributed to upland benefit employing “efficiencies”, such as grass filters. Efficiencies can vary by hydro-geomorphic region.
Chesapeake Bay Program Agricultural BMPs
- Nutrient Management
- Nutrient Management
- Precision Agriculture
- Enhanced Nutrient Management
- Conservation Tillage
- Continuous No-Till
- Conservation Tillage
- Cover Crops
- Cover Crops – Late Planting
- Cover Crops – Early Planting
- Small Grain Enhancement – Late Planting
- Small Grain Enhancement – Early Planting
- Pasture Grazing BMPs
- Off-Stream Watering with Fencing
- Off-Stream Watering without Fencing
- Off-Stream Watering with Fencing and Rotational Grazing
- Precision or Intensive Rotational Grazing
- Other Agricultural BMPS
- Forest Buffers
- Wetland Restoration
- Land Retirement
- Grass Buffers
- Tree Planting
- Carbon Sequestration/Alternative Crops
- Conservation Plans/SCWQP
- Animal Waste Management Systems
- Mortality Composters
- Water Control Structures
- Horse Pasture Management
- Non-Urban Stream Restoration
- Poultry Phytase
- Poultry Liter Management
- Dairy Precision Feed and/or Forage Management
- Swine Phytase
- Ammonia Emissions Reductions
Interim CBP Agricultural BMPs
- Nutrient Management
- Irrigation Management
- Passive Hay Management
- Manure Management
- Liquid Manure Injection
- Poultry Litter Injection
- Manure Processing Technology
- Poultry Litter Amendments
- Mortality Management
- Mortality Incineration
- Soil Amendments
- Phosphorus Absorbing Materials
- Nursery Management
- Nursery Runoff Management
- Non-Cost-Shared Practices
- Tracking and Reporting
The Pasture Management Science Panel Recommendations were covered next. The Chesapeake Bay Program’s Scientific and Technical Advisory Committee (STAC) and the Water Quality Goal Implementation Team (WQGIT) sponsored a series of two Pasture Management Workshops to provide a scientific forum for the evaluation of pasture and livestock management practices, implementation and tracking issues, and current assistance programs throughout the Bay watershed. The Panel Steering Committee members were: Dave Hansen, WQGIT Co-Chair, William Keeling, WTWG Chair, Mark Dubin, AgWG Coordinator, Liz Van Dolah, CRC-STAC, and Victoria Kilbert, CRC-CBPO. (Ed. note: The Northeast Pasture Consortium members Ray Bryant, Matt Sanderson, Howard Skinner, Kathy Soder, Jim Bonta, Lloyd Owens, and James Cropper participated in one or both workshops.)
The first workshop held on October 27-28, 2009 convened an initial science panel to develop draft practice definitions and model effectiveness values for preliminary model placeholders in the Chesapeake Bay Program Phase 5.3 modeling suite.
A second workshop was held on March 10-11, 2010 which convened a larger science panel to more adequately represent the Bay jurisdictions and organizations. The panel reviewed the draft recommendations of the first workshop and considered them in the preparation of final recommendations for development of a watershed-wide science-based report on pasture management systems.
The initial recommendation report was provided to the Chesapeake Bay Program partnership for review and consideration of adoption using the BMP evaluation protocol.
Due to the time-lines set by the WQGIT for detailed and specific recommendations to revise to the Phase 5.3 modeling suite, a fully documented final recommendation report will be published after the partnership review to address the documentation standards of the BMP protocol.
Pasture management BMPs recommended were alternative watering facilities, stream access control with fencing, prescribed grazing (PG), and a subset of prescribed grazing, precision intensive rotational grazing (PIRG). The model assumes that a stream-side pasture is 3% “degraded” and specifically along the stream corridor.
Alternative watering sites are assumed to provide an alternative source of clean water. It has been shown that livestock will spend less time watering in streams and thereby impact the stream and the stream bank less than without the alternative source of water. Alternative watering facilities typically involves the use of permanent or portable livestock water troughs placed well away from the stream corridor. The source of water supplied to the facilities can be from any source including pipelines, spring developments, water wells, and ponds. In-stream watering facilities such as stream crossings or access points are not considered in this definition. It is estimated that an alternative watering site will reduce N loading by 5%, P loading by 8%, and sediment loading by 10%. The modeled benefits of alternative watering facilities can be applied to pasture acres in association with or without improved pasture management systems such as PG or PIRG. They can also be applied in conjunction with or without stream access control.
With proper placement of the watering system, a better distribution of grazing and manure deposition occurs over the entire pasture as compared to the livestock using the stream exclusively for water. Research has indicated that these measures will reduce the time livestock spend in streams. This practice assumes a nutrient and sediment reduction value with alternative watering systems located remotely from the stream corridor. In-stream watering facilities, such as stabilized stream crossings or access points, in conjunction with stream access control with fencing is assumed to be a benefit to the stream corridor protection. The modeled benefits of this practice are applied against the pasture land use loadings versus the degraded stream corridor land use, as this is how this practice has historically been tracked and reported.
The Prescribed Grazing practice utilizes a range of pasture management and grazing techniques to improve the quality and quantity of the forages grown on pastures and reduce the impact of animal travel lanes, animal concentration areas or other degraded areas. PG can be applied to pastures intersected by streams or upland pastures outside of the degraded stream corridor (35 feet width from top of bank). An efficiency of TN 9/11%, TP 24%, and total suspended solids (TSS) 30% applied to each acre of improved pasture tracked and reported within appropriate Hydrogeomorphic Regions (HRMR) that demonstrate a predominance of subsurface versus surface storm water flow. The designated Hydrogeomorphic Regions (HRMR) for Phase 5.x of the model is as follows: Coastal Plain Dissected Uplands (CPD), Coastal Plain Lowlands (CPL), Coastal Plain Uplands (CPU), Piedmont Carbonate (PCA), Valley and Ridge Carbonate (VRC) and Appalachian Plateau Carbonate (APC). The modeled benefits of PG are applied against the pasture land use loadings of pastures intersected by streams or upland pastures outside of the degraded stream corridor (35 feet width from top of bank). The modeled benefits of prescribed grazing practices can be applied to pasture acres in association with or without alternative watering facilities. They can also be applied in conjunction with or without stream access control. Pastures under the PG systems are defined as having a vegetative cover of 60% or greater. Other benefits of this pasture management system include improved infiltration/runoff characteristics, healthier grass stands, reduced need for fertilizers or other inputs, and reduced erosion.
Stream access control with fencing practice involves excluding a strip of land with fencing along the stream corridor to provide protection from livestock traffic and grazing. The fenced areas may be planted with trees or grass, or left to natural plant succession, and can be of various widths. The ration-ale for using this practice is that direct animal contact with surface waters and the resultant stream bank erosion are primary causes of pollution from livestock. To provide the modeled benefits of a functional riparian buffer, the width must be a minimum of 35 feet from top-of-bank to fence line. If an entity is installing a riparian buffer practice in conjunction with stream protection fencing, and can track and report these installations, additional upland benefits of those riparian buffers can be applied in the model. The implementation of stream fencing provides stream access control for livestock but does not necessarily exclude animals from entering the stream by incorporating limited and stabilized in-stream crossing or watering facilities. Access Control with fencing is a land use change in the degraded corridor and buffered acres. The modeled benefits of stream access control can be applied to degraded stream corridors in association with or without alternative watering facilities. They can also be applied in conjunction with or without pasture management systems such as prescribed grazing or PIRG.
Streambank fencing and riparian buffer implementation reduces the nutrient, sediment, and fecal bacteria losses from the adjacent upland pasture, in addition to improving streambank stability, reducing sedimentation, and direct deposition of fecal matter.
If the stream corridor excluded is less than 35 feet wide from top-of-bank to exclusionary fenceline, the efficiency applied is a land use change converting acres of degraded stream corridor with stream access control to hay without nutrients if grass; or forest if trees are planted, tracked, and reported as such.
If the stream corridor excluded is 35 feet or greater in width from top-of-bank to fence line, the land use change converts acres as noted above, plus includes the nutrient and sediment reduction values as a functional grass or forested riparian buffer if tracked and reported separately. This practice also includes a ratio of upslope treatment area that is additive to any other pasture management efficiencies within that treatment area. These ratios are described in the number of pasture land use acres to riparian buffer acres receiving modeled nutrient or sediment reduction benefits; 4:1 for TN and 2:1 for TP and TSS.
The default value for the width of converted degraded stream corridors that do not have documented land use or width considerations will use the most conservative values; i.e. acreage conversion to grass without nutrients land use based on a 10 feet exclusion width from top of bank to fence line. In-stream watering facilities such as stabilized stream crossings or access points in association with stream access control systems will be assumed to be an integral part of the fencing system and will not be provided a separate nutrient and sediment effectiveness value.
The results of using a series of Pasture BMPs on sediment loads is shown in the graph shown below:
The results of using a series of Pasture BMPs on N loading is shown next.
Lastly, the results of using a series of Pasture BMPs on P loading is shown below.
The Precision or Intensive Rotational Grazing practice utilizes more intensive forms pasture management and grazing techniques to improve the quality and quantity of the forages grown on pastures and reduce the impact of animal travel paths, animal concentration areas, or other degraded areas of the upland pastures. PIRG can be applied to pastures intersected by streams or upland pastures outside of the degraded stream corridor (35 feet width from top of bank). The modeled nutrient and sediment effectiveness values of PG and PIRG are currently equal due to the current unavailability of scientific data within the region documenting nutrient and/or sediment differences between PIRG versus PG grazing systems. The PIRG practice is placeholder for future research and documentation for modeling the possible water quality benefits of more intensive pasture management systems.
A comparison of the Pasture Management BMP loading reduction values used with the different versions of the Chesapeake Bay Watershed Model is shown in the tabular values below.
-Alternative Watering Facilities (former Off-Stream Watering without Fencing BMP)
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Phase 4.3: TN 30%, TP 30%, TSS 38%
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Phase 5.2: TN 15%, TP 22%, TSS 30%
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Phase 5.3: TN 5%, TP 8%, TSS 10%
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Phase 5.3R: TN 5%, TP 8%, TSS 10% (stand-alone practice effectiveness values)
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Steam Access Control with Fencing (former Off-Stream Watering with Fencing BMP)
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Phase 4.3: TN 60%, TP 60%, TSS 75%
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Phase 5.2: TN 25%, TP 30%, TSS 40%
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Phase 5.3: Land Use Change/Upslope Ratio Reductions
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Phase 5.3R: Land Use Change/Upslope Ratio Reductions(stand-alone prct. effectiveness values)
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Prescribed Grazing (former Upland Pasture Management BMP from BMP Project)
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Phase 4.3: TN 0%, TP 0%, TSS 0%
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Phase 5.2: TN 20%, TP 20%, TSS 40%
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Phase 5.3: TN 10%, TP 20%, TSS 30%
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Phase 5.3R TN 9%/11% , TP 24%, TSS 30% (stand-alone practice effectiveness values)
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Precision Intensive Rotational Grazing (PIRG) (former Upland Pasture Management BMP from BMP Project)
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Phase 4.3: TN 0%, TP 0%, TSS 0%
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Phase 5.2: TN 20%, TP 20%, TSS 40%
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Phase 5.3: TN 10%, TP 20%, TSS 30%
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Phase 5.3R TN 9%/11% , TP 24%, TSS 30% (stand-alone practice effectiveness values)
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Off-Stream Watering with Fencing and Rotational Grazing
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Phase 4.3: TN 20%, TP 20%, TSS 40%
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Phase 5.2: TN 20%, TP 20%, TSS 40%
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Phase 5.3: TN 15%, TP 28%, TSS 40% (Off-Stream Watering effectiveness included)
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Phase 5.3R: Stand-alone practices that can be individually stacked
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AWF: TN 5%, TP 8%, TSS 10%
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SACF: Land Use Change/Upslope Ratio Reductions
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PG/PIRG: TN 9%/11% , TP 24%, TSS 30%
It is felt that the newest phase of the watershed model has the best scientific estimates for the different pasture BMPs reduction of N, P, and total suspended sediment. Continuing work by people such as Lloyd Owens and James Russell, the two previous speakers may give us even better estimates later.