*Overview of the Virginia Farm Assessment System

Table of Contents

Introduction

I. Distance from Well/Spring

II. Site Characteristics

III. Design and Management A. Clean Water Diversion B. Runoff Control System C. Feedlot Cleaning or Scraping

IV. Concentration of Animals and Type of Yard Surface

V. Abandoned Livestock Yards and Poultry Houses

Contacts and References

Glossary No. 8

Worksheet 8

 

Introduction

Livestock and poultry yards, such as barnyards, holding areas and feedlots, and areas around production buildings are areas of concentrated animal wastes. They can be a source of nitrate and bacteria contamination of groundwater. This is especially true if there is no system to 1) divert clean water flow from the livestock/poultry yard, 2) drain surface water away from wells or springs, or 3) collect polluted runoff from the yard for diversion to an area where its effect on surface water or groundwater is minimal. The potential for livestock and poultry operations to affect groundwater is greatest if the facility or area of animal concentration is located on karst terrain or over sandy-textured permeable soils, or when the water table is at or near the surface, bedrock is within a few feet of the surface, or polluted runoff is discharged to permeable soils and bedrock.

The federal and state standard for nitrate in drinking water is 10 milligrams per liter [mg/l; equivalent to parts to million (ppm) for water measure] nitrate-nitrogen. Nitrate levels above this standard can pose health problems for infants under 6 months of age, including the condition known as blue baby syndrome (methemog-lobinemia). Fecal bacteria in livestock and poultry wastes can contaminate groundwater if waste seeps into nearby wells or springs, partially leading to such infectious diseases as dysentery, typhoid, and hepatitis.

Young livestock are also susceptible to health problems from high nitrate-nitrogen levels. Levels of 20-40 mg/l in the water supply may prove harmful, especially in combination with high levels (1,000 mg/l) of nitrate-nitrogen from feed sources.

Other good reasons for improving management practices include improved herd and flock health, ease of maintenance, odor and fly control, and improved quality milk or meat production.

Return to Table of Contents.

 

I. Distance from Well/Spring

Wells and springs should be located upslope from the livestock and poultry feed yard and buildings so that runoff will drain away from the water source. The Virginia water well code requires a minimum separation of 150 feet between existing yards and new wells. With good farmstead planning, livestock and poultry facilities should be at least 300-400 feet away from the house. In this case, since the well is often near the house, it is likely that there would be at least 200 feet between the well and the feed yard or open lot surface. Minimum separation distances regulate new well installations, as well as the distance from existing wells to new sources of contamination. Existing wells are required by law only to meet separation requirements in effect at the time of well construction. Make every effort, however, to meet current regulations whenever possible.

Return to Table of Contents.

 

II. Site Characteristics

Groundwater protection should be a major consideration in siting feed yards, holding pens, or production buildings. Factors to consider include topography, soils and geology. Important soil characteristics include surface and subsoil texture, depth, and permeability. A very poor site has shallow soil, a high water table, or a very sandy/gravelly soil with excessive drainage and high permeability. For more assistance in assessing your site's vulnerability to groundwater contamination, see Fact Sheet/Worksheet No. 1, "Site Evaluation: Groundwater, Soils, and Geology".

For existing feed yards on poor sites, the best options for protecting groundwater might be replacement with total confinement buildings with concrete floors for the livestock or poultry, or providing paved yards and liquid-tight basins (e.g. clay-lined or artificial liner) to store open yard runoff. The lot slope should be 3-4% (uniform grade) to allow rapid water drainage into the designed basin.

Return to Table of Contents.

 

III. Design and Management

 

A. Clean Water Diversion

One way of reducing water pollution from livestock feed yards is to reduce the amount of clean water entering the open lot. In all cases, the following structures need to be in place and maintained:

• Waterways, small terraces and roof gutters to direct water away from livestock and poultry pens and buildings.
• An earthen ridge or diversion terrace constructed across the slope upgrade to prevent runoff from entering the yard.
• In some areas, if a diversion terrace is not practical, a catch basin with a pipe outlet could be installed above the yard.

Return to Table of Contents.

 

B. Runoff Control System

An open lot without a runoff control system typically has an earthen surface compacted by animal traffic. This surface needs to be shaped to a uniform grade for water drainage so it will remain relatively dry except during and immediately after rainfall. Manure typically accumulates on the surface and is mixed into the soil by animal traffic, thereby sealing the surface and reducing infiltration.

Water that runs off concrete pads, such as those located near barn doors, loading docks and material handling areas, and clean water that drains from roofs and upslope areas can wash manure from the open lot surface and create mudholes. Planning for such runoff is necessary.

Uniform drainage of the open lot surface is necessary, and the absence of runoff controls may lead to surface water quality problems. Contaminated runoff that accumulates in areas adjacent to an active feedlot may seep through the soil and threaten groundwater quality. This risk is greatest with soils of high infiltration capacity, such as sands and other soils with moderate to rapid internal drainage.

Runoff control systems can remedy such problem situations. Producers should collect runoff for storage and later land application (See Fact Sheet No.9, Section V). For frequently used livestock pens, these systems collect feedlot runoff, settle out manure solids, and direct the remaining runoff water through filter strips, and away from streams, ditches, waterways and areas of permeable soils and fractured bedrock. Figure 1 shows a typical livestock feedlot runoff control system for an open lot surface.

Return to Table of Contents.

 

C. Feedlot Cleaning or Scraping

Clean feedlot and pen surfaces regularly. The amount of manure on a feedlot surface depends on the animal density (square feet per head), hours per day animals spend on the open lot, animal size, and type of feed ration. Cleaning or scraping at least once per week is preferable. Concrete surfaces are easier to clean than earthen lots. Earthen yards are not recommended in Virginia, but may be cleaned when dry, which will result in less frequent removal of solids.

Return to Table of Contents.

 

IV. Concentration of Animals and Type of Yard Surface

The area needed per animal to minimize the risk of groundwater contamination depends on the type of lot surface. The amount of concrete surface area needed is much less than that required for an earthen lot. The concrete area needed is a balance between traffic on the lot and the resting area provided for animals. Too small an area will result in animals having difficulty moving about under wet conditions in pens, while too large an area is an extra expense and generates more runoff. For dairy operations, the best protection for groundwater is to confine animals to a freestall barn or roofed feeding barn. Where a yard is desired, 75 square feet of concrete per cow is recommended (400 square feet of earthen surface) and, if it will be used, about 2000 square feet of exercise area.

Where earthen lots will be used, maintenance of a compacted manure layer on the earthen open lot surface may help retard infiltration and reduce the amount of nitrate. Curbs will keep runoff from flowing off the edges of the concrete lot onto earthen areas.

The type of lot surface used also affects management. Earthen yards, for example, might be cleaned only once or twice per year. If a porous condition such as fractured bedrock is close to the surface where your livestock yard is located, it is advisable to pave the surface.

The "Dairy Loafing Lot Rotational Management System" has been approved as a cost-shared Best Management Practice (BMP) under the Virginia Department of Conservation and Recreation-Division of Soil and Water Conservation. This practice provides three grass loafing paddocks (about 33 cows/acre each) and one "sacrifice" paddock for use by a typical dairy herd outside the barn. Cows are allowed to rest on a paddock until surface conditions dictate rotation to one of the other paddocks. During wet periods, or when grass sod is likely to be damaged or destroyed, cows are placed in the "sacrifice" lot or confined to the barn until paddock conditions improve. The sacrifice paddock is typically protected from generating direct runoff to streams by location of the grassed paddocks. Figure 2 shows a schematic diagram of a dairy loafing lot rotational management system.

Return to Table of Contents.

 

V. Abandoned Livestock Yards and Poultry Houses

In active feedlots and yards, the manure/soil mixture over compacted soil forms a barrier through which water moves very slowly. Therefore, rapid leaching of nitrate and bacteria through the surface seal and compacted layers is not likely. However, if this manure/soil layer is removed, or if open lot runoff is discharged to permeable soils, sinkholes, or bedrock, leaching to groundwater may occur.

Abandoned poultry houses or old earthen poultry house foundations can be threats to farmstead water sources. Similarly, abandoned feedyards and barn-lots also pose groundwater contamination risks. If you have such a lot or structure, collect all manure or litter, and spread it on crop fields according to recommended nutrient management practices. In the case of earthen floor facilities, soil to a depth of one foot should be removed and spread with the manure or litter. The remaining hole should be filled and leveled. Litter packs remaining from demolished poultry houses should also be removed and properly land applied or stored. The soil area under the litter pack should be sampled and tested for nitrogen, phosphorus, potassium, sodium-chloride, nitrates, and sulfates.

If you have a permanently abandoned feedlot or corral, collect all the manure, spread the manure and soil mixture on fields following appropriate procedures, and refill the former feedlot surface with other soil material. Then till and plant to a high-nitrogen-using crop. Manure should also be removed from a feedlot that is not being used for an extended period. Otherwise, cracks developing in the surface may allow leaching of nitrate and bacteria.

Return to Table of Contents.

 

Contacts and References

For additional information, consult the Virginia Farm*A*Syst Resource Directory. For assistance in sampling, interpreting results, and dealing with remaining problems, contact your Cooperative Extension or Natural Resources Conservation Service office.

For additional information, you may contact your local Virginia Cooperative Extension or Natural Resources Conservation Service office, or the Virginia Department of Conservation and Recreation Division of Soil and Water Conservation Office.

Acknowledgements.

Return to Table of Contents.

 Worksheet 8 "Livestock and Poultry Yard Management."

View a list of the Virginia Farmstead Assessment System publications.

 

Reviewed by Bobby Grisso, Extension Specialist, Biological Systems Engineering

Other resources in:

• Natural Resources & Environmental Quality

Other resources by:

• Eldridge R. Collins, Jr.

Other resources from:

• Biological Systems Engineering