Ohio State University Fact Sheet

Animal Sciences

2029 Fyffe Road, Columbus, OH 43210-1095

Questions Pertaining to Large Dairy Enterprises in Ohio: Environment

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How do you know if an area's water supply can support a large farm?

There are several methods that can be used to determine the impact of a large dairy farm on water supplies. The first approach is to look at the availability of ground water in the area. The Ohio Department of Natural Resources (ODNR)–Division of Water publishes groundwater availability maps that indicate the general availability of groundwater supplies, the geologic materials, the depth of the water, and the general quality of the water. They also have records of all the wells drilled in the state. On-site pumping tests can also be used to evaluate the impact of water use.

Are there soil types or locations, such as flood plains, that should not be considered for locating a large farm?

Flood plains are areas near streams or rivers that flood during periods of heavy rain. Flood plains are not suitable for livestock farms or manure storage facilities. Flood waters can be dangerous to livestock, and manure can be carried from the farm via flood waters and result in stream contamination.

Soil type should always be considered when investigating sites for construction of manure lagoons and when planning manure utilization practices. Heavy clay soils present problems with drainage, ponding, compaction, and cracking. Sloping or highly erodible soils cause limitations because of potential problems with runoff and erosion.

On sandy or gravely soils, farmers need a cement, clay, or plastic liner for manure storage facilities to assure that ground water is not contaminated. Lagoons or storage ponds should meet specifications from the Natural Resource Conservation Service (NRCS) to assure proper containment.

Siting barnyards, feedlots, or manure storage facilities above shallow water tables that supply shallow wells should be avoided, particularly where soils are very porous. Such sitings may encourage movement of many undesirable substances into the water supply, including ammonia, nitrate, manure solids, and perhaps pathogens associated with the livestock. The risk associated with elevated water tables relates to two processes: 1) treatment of applied waste in the soil depends on unsaturated soil conditions; little treatment of waste occurs in saturated soil, and 2) contaminants can travel quickly over large distances in saturated soil. Where water tables are located at considerable depth, wastewater will have more contact with aerated soil for longer residence times, and hence there will be more time for normal biophysical and biochemical processes to treat the wastewater to reduce the concentration of contaminants. Major contaminants in wastewater and animal wastes are treated within several feet of unsaturated soil. Shallow wells draw water from elevated water tables, and hence any untreated waste intercepted by the saturated zone may quickly contaminate wells and by-pass treatment in the unsaturated zone. Similarly, water tables should not intercept waste storage facilities.

The rate at which wastes can be applied without contamination to ground water or surface water is called loading capacity. Low infiltration values limit the rate at which liquid wastes can be absorbed by the soil. Shallow depth of a hardpan or bedrock or coarse particle size reduces the amount of liquid waste that a soil can absorb in a given period. The time that wastes can be applied is reduced by the soil being frozen or having free water at shallow depths. Low soil temperatures reduce the rate at which the soil can degrade the material microbiologically. Sufficient depth to the water table should be maintained to allow the soil to filter out or otherwise remove substances. Specific depths will be dictated by the soil properties at the site.

Do deep cracks in clay soils put groundwater at risk when liquid manure is applied?

Surface cracks commonly seen in Paulding (a type of soil) and other clay soils during dry weather do not allow liquid livestock manure to threaten groundwater. These cracks may increase the rate at which water moves through the uppermost portion of the soil and into drainage tile. If the liquid manure enters drainage tile, then surface water can become contaminated and the risk increases for a fish kill. No more than one-half inch of liquid manure should be applied at any one time, outlet tiles should be closely monitored, and tile outlets may need to be temporarily plugged to encourage infiltration of the liquid manure into the soil. Proper manure application rates, presence of crop or residue cover, and disruption of the soil surface can greatly reduce the risk of manure contaminating surface water when cracks are present in soil.

Most groundwater in Northwest Ohio comes from bedrock aquifers that lie below thick layers of clay. This bedrock ranges from 50 to 200 feet below the surface. Laboratory tests show that the speed with which water moves through the clay (its permeability rate) will normally vary from one foot per year to 0.01 foot per year. Subsurface cracks that usually begin at 10 feet of depth and go to about 20 feet do not significantly increase the rate of downward water movement. Laboratory measurements made across cracks show permeability rates similar to those made on uncracked clay. When surface water has traveled downward through the clay to finally reach the bedrock aquifer, it will have had many years to purify.

How can a farm prevent manure from entering drinking water? Can manure be prevented from draining off a field via a drainage tile?

All roof and other surface areas should have eave spouting and other appropriate structures in place to prevent rainfall from becoming contaminated with manure. The soil surface around well casing should be sloped away from the casing, and well casings and water lines should be watertight and in good condition. Follow health department guidelines for testing of water for bacteria and chlorinating drinking water. Manure can be effectively prevented from draining off a field via a drainage tile if application recommendations are followed and if necessary tile outlets can be temporarily plugged.

What pathogens enter the water system through drainage tiles?

Some of the pathogens usually mentioned in this context include Salmonella spp., Escherichia coli 0157:H7, and cryptosporidia. Each of these organisms may be in cow manure and under some circumstances can cause serious disease in humans. However, an important point to consider is the usual route of exposure to humans by these pathogens. In most cases, locating cattle in a community, even if they are carrying these organisms, does not increase the risk of exposure to the general public. People working directly with infected cattle may be at increased risk but even they can greatly lower their chances of disease by using good hygienic practices (e.g., hand washing) and properly preparing food (e.g., thorough cooking of meat and not drinking unpasteurized milk).

Beyond adoption of principles of general hygiene and food preparation, each pathogen has its own characteristics that need to be considered:

1. Cryptosporidia – These organisms are single-celled parasites that quite commonly infect young calves. Infected calves may or may not have diarrhea. The oöcyst (egg) of the parasite is resistant to most disinfectants and may persist in an infective stage for months in cool moist environments. While the oöcyst can remain infective for a year in manure slurry, freezing and thawing will kill it. High temperatures (> 85°F) and sunlight will also cause the oöcysts to become noninfective. Cryptosporidia from cattle and other animals can and have caused disease in people. People whose immune system is compromised are at greatest risk. In healthy people the disease is self-limiting. Some of the first cases reported in the literature involved veterinary students who handled infected calves and didn't adequately wash their hands before eating. While efforts should be made to avoid contamination of surface waters with animal manure that may contain cryptosporidia, MOST of the outbreaks in human communities that have been documented have been the result of water contamination by human sewage (e.g., the Milwaukee outbreak in 1993). Molecular laboratory techniques permit scientists to differentiate the genotype of cryptosporidia normally carried by humans from those in which animals are the definitive hosts. While the research has not been completed it is at least conceivable that some cryptosporidia could enter tile drainage systems in some soils. However, research has shown that even after surface application of manure, there is considerable dilution of cryptosporidia organisms in the environment.
2. Escherichia coli 0157:H7 – The usual means of exposure to people is by eating meat that is not properly cooked. Water exposure has occurred where there has been cross-contamination of sanitary water systems.

   The organism is easily killed by disinfectants, sunlight, and drying. If drainage tiles were contaminated, it is unlikely the organisms would survive long enough in the ditches to have any effect on public health.

3. Salmonella spp. – The usual means of human exposure would be from direct handling of infected livestock, drinking nonpasteurized milk, or eating foods that had been contaminated and not properly handled or cooked. The organism can survive in the soil under fecal pats or in slurry for 9-12 months. However, it is highly susceptible to sunlight, drying, and most disinfectants and dies quickly when exposed to these.

How can a large farm control flies?

Managing manure properly is the best way to control flies on dairy farms, solving at least 75 percent of the fly control problem. Manure is a favorite place for flies to lay their eggs. With most dairy farms using free stall housing and avoiding bedded manure packs, less manure remains in the animal housing for infestation by flies. The use of lagoons and pits for manure storage also prevents flies from laying eggs in the manure because there is an inadequate amount or type of biomass to provide ova position stimulant (stimulant that must be present for flies to lay eggs). Also, products are available to control flies on the animals and pesticides are available for use in the milking facility (for more information, refer to the OSUE Bulletin 473, Livestock and Livestock Building Pest Management, http://ohioline.ag.ohio-state.edu/b473/index.html).

How can a large farm control rodents?

Dairy farms adhere to regulations set up by the U.S. Department of Agriculture regarding sanitation procedures and building "codes" in the milking areas. The Ohio Department of Agriculture (ODA) inspects all Grade A dairy operations at least once every six months and inspects all manufacture grade milk operations at least once every twelve months. The visits involve inspection of the maintenance and cleanliness of the milking structure and milking equipment, use of proper milking procedures, handling and cooling of milk, and pest control. Control of rodents around the milk house and livestock structures is best accomplished by minimizing their access to a food supply. Dairy farmers control rodents by proper storage of feed, proper disposal of spoiled feed, and limiting areas attractive as living quarters for rodents. Dairy farmers must control rodents to minimize costs caused by feed loss, damage to livestock and feed structures, and to minimize spread of disease carried by rodents.

How can a large farm control odor?

The odor from dairy farms comes from the manure and not the animals themselves. The OSUE Bulletin 604 (http://ohioline.ag.ohio-state.edu/b604/index.html) provides some information in the section on controlling odors. Proper storage, preparation, and application of manure to soils can all help minimize odors. For example, injecting liquid manure limits volatilization and prevents surface runoff. Applying manure during humid, low wind speed days should be avoided because the odor will linger in the area longer. If manure must be spread on warm days, it should be spread in the morning. Lower pressure nozzles (less than 80 psi) should be used to reduce the aerosol effects of fine droplets, and low trajectory nozzles to reduce drift. During irrigation, allow for a buffer zone of 50 ft from roads and 200 ft from residences when the wind is blowing away from the roads or homes. If the wind is blowing in the direction of the structures, increase the width of the buffer zone. And, of course, manure application should be avoided during days when family events are likely (e.g., holidays, etc.) to minimize nuisances. The Soil and Water Conservation District personnel work with farmers to choose the best site for manure storage and to develop manure management plans that minimize odor. Research continues to investigate ways of reducing odor from animal manure.

How is manure stored on large farms?

All animal producers are encouraged to provide adequate manure storage. Adequate storage implies that the storage facility is both large enough to contain manure through the periods of time in which it is less desirable to apply manure to cropland and constructed to provide accepted levels of containment. The USDA-NRCS (Natural Resources and Conservation Service) primarily is responsible for implementing standards for both storage duration and construction. Operations that seek a Permit to Install (PTI) from the Ohio Environmental Protection Agency (OEPA) or substantial cost-share funds from the Soil and Water Conservation District (SWCD) are required to demonstrate that adequate manure storage will be provided.

Manure can be stored in indoor facilities, such as deep pits, bedded packs, dry litter systems, or stored outside the facilities, such as tanks, ponds, and lagoons. Most modern dairy operations generate liquid manure. Storage structures are commonly constructed using compacted earth (clay), concrete, steel, or a combination of these materials and may be constructed above ground, below ground, or part in and part above ground. If sand is used as bedding, the storage facility for sand-laden manure often will have a concrete bottom to allow the operator to clean out the entire facility.

Quality design and construction of facilities for containing liquid manure help to ensure that material does not leak through the structure or spill out of it and get into groundwater or surface waters. Proper site investigations, lining, and storm water control need to be provided. Permitted operations must demonstrate that these measures are taken. Dairy operations that do not have the number of animals requiring a permit are recommended to voluntarily take these measures to demonstrate their commitment to stewardship of the natural resources and to improve their standing in case a pollution lawsuit is brought against them. Once constructed, the facilities also need to be managed as intended in the design.

Most dairy operations in Ohio and the surrounding region store manure without "treating" it. Therefore, no matter what a facility is made of, looks like, or is called, its function is storage of manure unless it was specifically designed and is managed to treat the manure. Most manure is stored on these farms in an anaerobic state, meaning oxygen is limited except at the surface. Without treatment, odorous gases will be generated within this manure and odor control should be considered, especially when the storage is being emptied.

How can manure be applied safely?

Application of manure in an environmentally and economically prudent manner begins with a manure nutrient management plan. A sound plan for managing manure nutrients identifies application rates that meet crop nutrient needs, minimizes the need to use additional fertilizer, recognizes potential impacts to the environment, and establishes the basis for operating without degrading the environment.

Manure should be applied at agronomic rates. This means the nutrients that are readily available in the soil plus nutrients from other sources, such as manure, are matched with the expected nutrient requirements of the next or growing crop. Application of manure at agronomic rates minimizes the potential for nutrients to move out of the crop's root zone and maximizes the manure's nutrient value to the landowner.

Well-designed plans also account for local conditions that could affect the fate of manure after it is applied to the land. Such conditions include soil type, terrain, field moisture levels, and expected weather patterns. Potential environmental impacts are minimized through the use of adjusted application rates and management practices that are appropriate for the given crop and local conditions. Manure application rates may need to be adjusted downward to prevent saturating the soil, erosion, and/or runoff. An example of a best management practice is the immediate incorporation of manure into the soil, which minimizes the potential for manure to run off of a field.

State and national regulations restrict the application of manure onto crops that may be marketed for human consumption as fresh produce. Enforcement of these regulations preserves food safety by ensuring that manure-borne pathogens are destroyed (through either designed or natural processes) before they reach consumers' tables.

Are commercial applicators of manure certified?

Currently, commercial manure applicators are not required to be certified to land-apply animal manure. They are, however, required to follow the nutrient management plan of the producer who hires them.

Editors

Maurice L. Eastridge, Professor, Department of Animal Sciences, The Ohio State University

Suzanne Steel, Director of College Communications, Communications and Technology, College of Food, Agricultural, and Environmental Sciences, The Ohio State University

Technical contributors

Glen Arnold, Assistant Professor, Ohio State University Extension, Putnam County

Maurice L. Eastridge, Professor, Department of Animal Sciences, The Ohio State University

Donald Eckert, Professor, School of Natural Resources, The Ohio State University

Kevin H. Elder, Executive Director, Livestock Environmental Permitting Program, Ohio Department of Agriculture

Kent Hoblet, Professor and Chair, Department of Veterinary Preventive Medicine

Denise Lange, Water Quality Coordinator, Defiance CountyNatural Resources and Conservation Service

Brain Slater, Professor, School of Natural Resources, The Ohio State University

Richard Stowell, formerly Assistant Professor, Department of Food, Agricultural, and Biological Engineering, The Ohio State University