BMP’s: What are they?
Best Management Practices (BMP’s) are land management practices that lessen the environmental impact of an activity. There are hundreds of different BMPs that address different impacts of agriculture, and adopting even a few can often make a huge difference. In many cases, these BMP’s may have economic benefits improving efficiency of operations and/or increasing production.
The NRCS has an exhaustive list of BMPs for managing crop and forest lands and raising livestock with over 170 different BMP’s eligible for federal funding or cost-share through numerous USDA programs. Some of the most important BMPs for water quality are discussed briefly below, but for more detailed information, visit http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/technical/cp/ncps/?cid=nrcs143_026849 or contact your local USDA service center (see page 13 for contact info).
ATTRA, the National Sustainable Agriculture Information Service, is another good source for information on sustainable agriculture practices, and provides hundreds of free, in depth publications on virtually any agricultural topic you could imagine, from conservation easements to organic tobacco and even ostrich farming! For more information or to order one of their publications, visit www.attra.ncat.org or call 1-800-346-9140.
Cropland BMPs: Keeping nutrients and soil on your land and out of the stream
One of the biggest sources of water pollution from agriculture is nutrients and sediment moving from farm fields and lawns to nearby waterways. This is a lose-lose situation – no one wants to lose precious soil and nutrients when they could be going toward supporting a more productive crop. Luckily, there are lots of ways to help manage this problem and many of them qualify for federal cost-share programs.
- No-till farming: no-till farming involves the use of seed drills to plant crops without tillage. No-till farming decreases erosion, enhances moisture retention, and helps compacted soil recover to healthy conditions. In addition, this form of farming is on the rise nationwide, and there is increasing development of new machinery to facilitate no-till farming for additional crops.
- Strip-till farming: where no-till is not an option, strip tilling can be a good compromise between the benefits of conventional tillage and no-till. By tilling only the seedbeds, soil loss and compaction can be reduced.
- Cover crops: In between growing seasons, cover crops prevent erosion of fallow land, reduce runoff, and can help reduce weed pressure. In a conventional tillage system, leguminous crops can be grown and tilled into the soil to provide additional nitrogen. In a no-till or strip-till system, crop residue from cover crops can reduce weed pressure, retain moisture, and prevent erosion during the growing season, and many cover crops can also be harvested.
- Conservation crop rotation: crop rotations planned in a way that conserves the soil and minimizes fertilizer/pesticides/herbicides.
- Nutrient/pesticide/herbicide management: Pesticides and nutrients are major sources of pollution in rural waterways, and proper management of them is essential. Correct calculation of nutrient needs and pesticides can minimize pollution and lower costs.
- Integrated pest management (IPM) – an approach to managing pests combining biological and physical pest control strategies and targeted pesticide use to minimize the quantities of pesticides applied.
- Agrochemical handling facilities: Allow for proper storage and disposal of herbicides/pesticides and tank wash water, and reduce the chance for chemical spills.
- Precision agriculture: The rise of GPS technology now allows producers to map in-field variables such as crop yield, nutrient levels, and moisture content, so excess nutrient and water use is minimized. Fertilizer and water can be delivered in the proper amounts based on need, reducing excess nutrient runoff and saving money!
- Tile drains: Avoid tile drains wherever possible. If you must use a tile drain, consider using a denitrifying bioreactor or artificial wetland at the outlet to help absorb excess nutrients in the drain water and limit flash flooding.
- Contour farming: water runs downhill, and if you have a sloping field, farming along the contours of your landscape can help reduce erosion
- Manure management: If using manure as a fertilizer source, using a manure injector for liquid manures can reduce odors, limit impacts on air quality due to volatile gases, and reduce nutrients and pathogens in stormwater runoff. New technology has recently developed to apply this injection concept to dry manures such as poultry litter as well.
- Critical area planting: Setting aside areas at high risk for erosion can prevent migration of rills and gullies onto adjacent cropland
- Contour buffers, field borders, and strip-cropping leave grass strips along contours, field edges, or between strips of crops, helping infiltrate field runoff and minimizing erosion and nutrient pollution.
- Grassed waterways: grassed waterways balance field drainage with infiltration/erosion reduction, and can be useful for areas that flow in wet weather
- Vegetative barriers: Rows of shrubs or trees between fields can help trap runoff and reduce water and wind erosion and nutrient transport
- Crop diversity: Growing a wide range of crops on a farm can help reduce the negative impacts of monoculture crop production. Additionally, a diverse crop portfolio can help reduce economic risks from weather, pests, or market conditions.
Livestock BMPs: Healthy streams, healthy livestock
Whether you raise a few animals or a large herd, there are practices that can improve the health of both your water and your livestock. For more detailed information, visit http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/technical/cp/ncps/?cid=nrcs143_026849 or contact your local USDA service center (see page 13 for contact info).
- Rotational grazing: Moving livestock between multiple fields limits grazing pressure in any one area, reducing erosion and nutrient and pathogen pollution in runoff. Can be done with permanent fencing or temporary electric fencing.
- Exclusion fencing: Fencing livestock away from natural water sources prevents contamination by pathogens and nutrients, and helps keep stream banks intact. Cattle exclusion in combination with an alternative water source may also improve livestock health by keeping livestock off of steep, slippery banks where they could be injured.
- Alternative water sources: providing a pump-fed drinking trough or tank allows cattle to drink without needing a natural water source such as a pond or stream. Building a multi-field tank at a fence line or corner between multiple pastures can simplify rotational grazing setup when using permanent fencing. Avoiding direct watering can also have positive health impacts for livestock (preventing access to potentially contaminated water).
- Heavy-use areas: Prevent livestock from damaging soil or causing erosion when congregating at water sources, hay ring, or other location using mobile hay wagons and water troughs
- Stream crossings: Using a bridge or culvert is preferable, but if a stream crossing for livestock is necessary, it should be hardened to minimize erosion. Stream crossings should also be relatively narrow, to prevent livestock from lingering in the stream.
Forestry and Nursery BMPs: Keeping our forest streams healthy
Forestry involves the use of dozens of possible management practices, of which a few are mentioned here. Recent surveys have shown wide adoption of these management practices (nearly 90% adoption for some BMPs) in Tennessee – so don’t be left behind! If you are a logger or simply a landowner who is selling timber rights on your land, learn how to make sure the harvest protects your waterways.
- Riparian buffers: retaining forest along streams helps prevent erosion, maintains tree canopy to keep streams shaded (high stream temperatures are problematic for many aquatic species), and limits excess organic matter and nutrients from reaching the stream
- A compromise between a full buffer and clear-cutting is a streamside management area with partial cutting within the riparian zone (<50% harvest) and careful sediment management
- Conservation easements to protect vulnerable forest areas.
- Properly designed forest roads and stream crossings/culverts to minimize erosion and allow fish passage
- Uneven-aged selection forestry: Clear-cutting can be extremely damaging to forest wildlife, and can increase erosion. Consider ongoing individual tree or group selection as an alternative. This method is more complex than clear-cutting but can create a more natural looking and healthier forest
- Cover crops: Use of cover crops or other sediment control measures to reduce erosion after harvesting, especially if clear-cutting.
- Agroforestry: Includes numerous co-growth activities such using the space between tree rows for crops or pasture, growing shade crops in forests, or including species at the outer edge of a riparian buffer that generate additional income through non-timber production.
For guidance on forestry best management practices, visit http://www.tennessee.gov/assets/entities/agriculture/attachments/AgForBMPs.pdf or contact your local TDEC Division of Forestry Office for more information (see contacts section).
Edge of Field/Waterway BMPs: Keeping our rural streams healthy!
Whether you own a farm, ranch, or just live in the country there are practices that help keep our rural waters healthy. See the “BMP’s: How do I Pay for Them?” section for suggestions on how to cover implementation costs! For more information, contact your local USDA service center (see page 13 for contact info), or visit http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/technical/cp/ncps/?cid=nrcs143_026849.
- Riparian buffers: Leave forested buffers of 50-100 feet between cropland or pasture and a stream or waterway whenever possible. Riparian buffers help trap sediment and filter nutrients, pathogens, and other pollutants out of edge-of-field runoff. Where forest is not practical, grass or shrub buffers (or a combination of the two) are also useful.
- Karst sinkhole treatment: In limestone rich areas, sinkholes can carry run-off to the nearest stream much more rapidly than in non-karst terrain. Leaving a protective buffer around sinkholes can be critical for maintaining local groundwater and stream water quality.
- Wetland preservation: Preserve existing wetlands between the field and the stream – these ecosystems are important for migrating birds and help control flooding, trap sediment, and filter pollutants from edge-of-field runoff.
- Wetland creation: Artificial wetlands can have the same benefits as natural ones, but are installed strategically to filter field runoff.
- Floating wetlands: Floating wetlands can be used in ponds, wastewater treatment lagoons, or other locations with highly variable water levels. They are designed to maximize root surface area in contact with the water in order to pull as many nutrients and pollutants out of a polluted water source as possible.
- Streambank and shoreline protection: Protecting the streambank from erosion helps limit sediment pollution and preserve land. Use natural methods, such as replanting with live stakes, when possible, rather than riprap or hard-armoring.
- Aquatic organism passage: Small headwater streams are often critical habitat for small fish. Using bridges or natural bottom culverts for farm or forest roads and other stream crossings provides connectivity between fragmented habitats, allowing these animals to thrive.
- Denitrifying bioreactor or wall: tile drains can deliver large quantities of nutrients to nearby streams. Denitrifying bioreactors provide carbon-based material (usually wood chips or sawdust) in an underground chamber to provide food for bacteria that break down nitrates from the drain tile system. A denitrifying wall is a similar practice, consisting of a small trench filled with wood chips that filters nitrogen rich shallow subsurface groundwater as it flows toward the nearest stream. Denitrifying bioreactors have recently been added to the NRCS list of approved conservation practices so many more funding sources are now available for funding them.
- Grade-stabilization structures: In the field or at its edge, in ditches or other drainage features, grade stabilization structures can limit erosion at gully heads, reducing erosion and preventing further migration of gullies onto agricultural land.
- Sediment basins: Edge of field basins trap edge-of-field sediment, reducing sediment delivered to nearby streams
Other Ways to Keep Our Waters Healthy
- Energy efficiency/renewable energy sources: Improving energy efficiency of your buildings or installing renewable energy sources such as solar can help save money and limit our dependence on coal. Improving efficiency or converting to renewable energy sources can be a great way to save money on electricity costs.
- Cisterns: Cisterns capture rainwater off of building roofs, reducing stormwater runoff, limiting erosion, and providing a potential alternative water source for livestock (or humans if filtered correctly).
- Invasive species control: Avoid using invasive Asian carp species (bighead, silver, black, or grass) for algae control in ponds. These are widespread invasive species, and are illegal in Tennessee (with the exception of sterile triploid grass carp). Avoid planting invasive species, as erosion control, windbreaks, or even for decorative purposes. Kudzu was once widely planted for erosion control, but now we know better! Chinese privet, autumn olive, and tree of heaven are just a few of the many invasive species threatening Tennessee’s forests. Many of these species can negatively affect riparian zones and destroy native plant communities. The Tennessee Exotic Pest Plant Council (TNEPPC) provides a comprehensive list of invasive species in Tennessee and native alternatives. For more information visit http://www.tneppc.org/pages/landscaping#alternatives