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Agricultural BMPs

Agricultural BMPs are implemented on agricultural land and include practices which help to control erosion and improve water quality. There are specific BMPs that help control animal waste, prevent or reduce pollution associated with the use of nutrients, pesticides and fertilizers, maintain or improve soil productivity, and help control erosion by restoring plant growth. The following is a list of practices to consider for specific problems.

To control erosion and sediment loss from cropland:

  • No-till
  • Conservation tillage
  • Strip cropping
  • Contour farming
  • Terraces
  • Ponds
  • Water and sediment control basins
  • Grade stabilization structures
  • Streambank stabilization
  • Grassed waterways
  • Cover crops
  • Filter strips

Controlling and managing animal waste:

  • Structural systems (lagoons, holding ponds, dry stacks)
  • Diversions
  • Filter strips
  • Vegetative waterways
  • Dead bird composting
  • Animal waste utilization
  • Irrigation systems

To improve water quality and soil productivity and to prevent forest land erosion:

  • Treatment of logging roads, skid trails, firebreaks and log landings
  • Improvement, protection, and restoration of streamside lands (riparian zones)

Buffer Strips for Water Quality Control

Conservation buffer strips are areas or strips of land maintained in permanent vegetation. They are designed to intercept pollutants before they enter waterbodies. They provide wildlife habitat, enhance the appearance of the land and improve water quality. They are most effective when used with other BMPs.

Contour buffer strips are strips of perennial vegetation alternated with wider strips of cropland strips which are farmed on the contour. They can reduce sheet erosion and reduce movement of sediment, nutrients, and pesticides.

Filter strips are strips of grass or other vegetation used to intercept or trap sediment, organics, pesticides, and other pollutants before they reach a waterbody.

Riparian forest buffers are streamside vegetation consisting of trees, shrubs and other plants that can intercept pollutants from both surface and ground waters before they reach a stream.

Field borders are strips of perennial vegetation planted on the edge of a field. They can be used for turn areas or travel lanes for farm machinery.

Windbreaks/shelterbelts are row of trees, shrubs or other vegetation used to reduce wind erosion, protect young crops, and control blowing snow.

Grassed waterways are strips of grass on areas where water concentrates as it runs off a field. While they are used primarily to prevent gully erosion, waterways can be designed or combined with filter strips to help filter contaminants.

Alley cropping is an agroforestry practice consisting of growing trees or shrubs in rows or corridors with alleys of agronomic crops or forage between them. Both the forestry and agronomic crops are harvested.

Other practices considered as buffers or closely associated with them are hedgerow plantings, herbaceous wind breakers, cross wind trap strips, streambank protection measures, and vegetative barriers.

This information is part of the NRCS publication, Buffer Strips: Common Sense Conservation. The following two sections, Nutrient Management and Animal Waste Management are taken from the EPA publication, A Common Sense Guide to Rural Environmental Protection (EPA 904-B-92-002).

Nutrient Management

Testing the soil is an essential first step in nutrient management. Using too much of a nutrient is a waste of money and a burden on the environment. Plants use nitrogen in the form of nitrates, with the average uptake of nitrogen by crops being about 50 %. The rest is lost through leaching. When nitrates leach into groundwater, water supply from wells becomes contaminated, and most rural populations get their drinking water from springs and wells. The main causes of groundwater contamination are 1.) too much nitrogen is applied, 2.) the fertilizer is applied at the wrong time, or 3.) the fertilizer is applied to sandy or porous limestone soils that cannot retain it.

Another nutrient, phosphorus, is also essential for plant growth. Phosphorus, unlike nitrates, is insoluble in water and is bound to the soil and lost through crop uptake or erosion. When phosphorus is added to receiving streams, it encourages the overgrowth of algae and speeds up the aging process of lakes and ponds.

The following are some nutrient management strategies:

  • Control sediment erosion and runoff with filter strips between fields and open bodies of water to trap nutrients before they contaminate surface water.
  • Record the soil texture, drainage characteristics, weather patterns, and try to keep a record of previous field yields and amount and types of fertilizer used.
  • Test soil and manure to determine nutrient content. Soil should be tested in early spring, for pH as well as nutrient content. Manure should be tested every three years or when livestock bedding or feed is changed.
  • Apply manure and fertilizer when and where they are of the most use to the crop. Once the crop has passed the point of its highest nitrogen uptake, applied nitrogen will not be of any further benefit.
  • Use crop management that includes rotations, proper variety and hybrid selection, appropriate seeding rates, planting times, pest control, and water management to ensure that yield goals are met and applied nutrients are used. Apply cover crops to “scavenge” for unused nutrients.
  • Establish or manage vegetation along the banks of streams and drainage ways. Plants help remove pollutants from runoff before it enters streams and help increase infiltration into the soil. They also provide wildlife habitat.

Animal Waste Management

Even a small livestock operation generates a substantial amount of waste products. For example, one 50 cow dairy herd produces the equivalent of 100,000 lbs. of 10-4-8 fertilizer every year. In larger operations, the sheer volume of accumulated wastes can present a major disposal problem. If improperly handled, these by-products can contaminate ground and surface waters, and pollute rivers, streams and drinking water wells.

Treating animal wastes as a usable by-product or disposing of wastes properly can save you money and reduce your risk of damaging the environment. Effective management practices reduce fertilizers, improve soil quality, and protect water resources, air quality and health. The four parts of an effective waste management system include: collection, transportation, storage for use as fertilizer or for treatment and disposal, and treatment and utilization.

Collection: Collection methods include scraping, washing, and flushing and the use of slotted floors, which allow manure to drop into pits for removal. In poultry operations, scrapers on cables beneath cages are common. In swine production, sloping floors and collecting /flushing gutters are often used. Regardless of the method used, the system must be properly operated and maintained.

Transportation: The type of system you use to transport manure depends primarily on whether you are storing waste temporarily for use as fertilizer or are treating and disposing of it. Depending upon the operation, manure can be moved by manure spreaders, pumps, cross conveyors, or augers. In some operations, movement is through a liquid system such as gravity flow, flushing pits, or pumping.

Storage for later use as fertilizer: The purpose of storage facilities is to conserve nutrients and make the waste a better soil conditioner and fertilizer. The type of storage system-wet or dry, will depend on your operation and your nutrient needs. Regardless of which method is used, care must be taken to operate and maintain the system properly. If manure is stored improperly or for too long, it will decompose and nutrients will be lost.

Wet storage systems use storage ponds, concrete pits, and above ground tanks to store liquid wastes for a short time-up to 60 days. When needed, sludge and liquid are mixed and spread on the land. Advantages of a wet system include lower construction costs and a smaller required land area.

Dry storage systems allow longer-term storage-up to six months. The systems consist of a dry, covered stack and a separate storage pond to collect wash water from a milking parlor and/or runoff from feedlots. It is essential that the dry stack is covered and gutters and curbs installed to keep rainwater out of the storage area.

Treatment and Utilization: Apply animal waste in proper amounts and at appropriate times to meet the needs of growing crops. If over-fertilizing is a problem, especially in fields located near streams of lakes, consider treating animal wastes in a lagoon system. Lagoons lower the nutrient value of manure and other wastes and reduce the risk of water pollution. Phosphorus is reduced by as much as 90 percent.

Both solids and liquids, such as runoff or wastewater, are collected in the lagoon, which can be anaerobic or aerobic. Anaerobic lagoons break down animal wastes without using oxygen or aeration. These lagoons are small, but very deep, and odor is sometimes a problem. They cannot handle human waste. Aerobic lagoons use oxygen to break down animal wastes. They are shallower than anaerobic lagoons and need a larger land area. They also create less of an odor. Sludge from both types of lagoons must be removed periodically, and can be applied to the land as needed.

Operation and Maintenance: Whether you raise cows, swine, or poultry, one thing is certain. The success of your waste management system will depend in part on how well you maintain and operate it. To get the most value from your system:

  • Incorporate waste utilization into your crop nutrient management plan.
  • Establish collection schedules.
  • Apply waste on land at the right time, in the right place, and in the right amounts.
  • Manage surface runoff.
  • Control odors and pests.
  • Apply wastes away from streams and waterways.
  • Use sound safety guidelines.
  • Maintain grass filter strips.
  • Sample nutrient content of the waste and the soil regularly and keep accurate records.
  • Repair leaks to watering devices.
  • Ventilate properly to prevent buildup of toxic vapors or excessive humidity.
  • Check the weather before applying. Do not apply wastes before a predicted rain or when humidity is high.
  • Upgrade size of waste management facilities consistent with the size of the animal population.

A comprehensive waste management system will take these important things into consideration:

Land application: To obtain the greatest value from your animal wastes, first calculate how much nutrient the crop needs. Apply nutrients during the period of maximum crop uptake.

Runoff control: The runoff from a barnyard must be controlled to prevent pollution of surface and ground water. The amount of rainfall or snowfall is more important than the size of the barnyard when it comes to calculating potential pollution. Begin by taking a close look at the ways water enters the barnyard-from gutters, roofs, or upslope fields. Clean water should be channeled away from the barnyard. Water that flows through the barnyard must be diverted to a central settling basin or other treatment area. Up to 80 percent of manure solids can be removed in this way.

Protection of streams and ponds: Runoff from fertilized fields or livestock areas can seriously contaminate nearby streams and ponds with nutrients, bacteria, and organic matter. Consider putting up a fence to restrict livestock, or plant a barrier strip of native grasses or trees to reduce sediment flow. Water quality will be protected and wildlife habitat will be improved.