Swine Manure Management Systems for Barns

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Manure composition dictates system choice: Pig manure is approximately 90% water, containing organic matter, nitrogen, phosphorus, potassium, and pathogens. The decomposition of this organic matter produces dangerous gases like hydrogen sulfide, methane, ammonia, and carbon dioxide, with hydrogen sulfide being the most acutely lethal due to its olfactory fatigue properties.
• System selection hinges on barn type, climate, and resources: Deep pits are common for confinement barns, offering low daily labor and good nutrient retention but posing gas risks during agitation. Bedded packs suit colder climates and operations with ample bedding, generating heat but requiring more labor and space. Flush systems reduce barn odors and gas hazards but consume significant water, producing dilute effluent.
• Storage capacity is critical for nutrient management and regulatory compliance: A minimum of 6 months of storage is generally required to allow for application when crops need nutrients, preventing overapplication on frozen or saturated ground. Proper sizing avoids forced spreading in suboptimal conditions, which can lead to environmental damage and neighbor complaints.
• Ventilation and gas management are integral to manure handling safety: Underfloor pits require dedicated ventilation to exhaust gases like hydrogen sulfide and ammonia away from animal living spaces. Never enter a pit or storage without testing for dangerous gas concentrations (especially H2S > 10 ppm) and using appropriate safety gear, as agitation can rapidly release lethal levels.
• Nutrient value necessitates careful testing and application: Manure is a valuable fertilizer, but its nutrient content (N, P, K) varies significantly with diet and storage. Regular manure testing (at least annually) and application based on crop needs and soil test results are crucial to maximize fertilizer value and prevent environmental contamination from overapplication.
• Recordkeeping and safety protocols are non-negotiable: Comprehensive records of manure volume, nutrient content, and application details protect against audits and complaints, while strict adherence to safety protocols, especially during agitation and pit entry, is paramount to prevent fatalities from gas exposure.

Swine manure management is one of the most important operational decisions a pig farmer makes. The system you choose affects daily labor, pig health, neighbor relations, regulatory compliance, and the nutrient value of the manure you apply to crops. This guide covers the main manure handling systems for barns, how to design and manage them, common pitfalls, and how to monitor performance. It is written for farm owners, managers, and planners who are building a new barn or upgrading an existing one.

At a Glance

• Choose a system based on your barn type, climate, and available land. Slatted floors with pits work well for confinement barns. Bedded packs suit colder climates and operations with ample bedding. Flush systems save labor but use large amounts of water.
• Match pit storage capacity to your crop nutrient plan. Most operations need 6 months or more of storage so you can apply manure when crops need it.
• Ventilation is part of manure management. Pit gas control and barn airflow are connected. Never enter a pit or barn with suspected gas buildup without testing and proper safety gear.
• Agitate thoroughly before pumping. Stratified manure creates uneven nutrient application and can release dangerous gas pockets.
• Keep complete records of manure volume, nutrient content, and application. These records protect you in a complaint or audit and improve your fertilizer planning.
• Know your local rules before you build. Manure storage, setback distances, and application rates are regulated in most pig producing areas.

Understanding Swine Manure: Composition and Characteristics

Before you choose a handling system, you need to understand what you are dealing with. Pig manure is roughly 90 percent water. The remaining 10 percent contains organic matter, nitrogen, phosphorus, potassium, and a range of micronutrients. It also contains bacteria, viruses, and gases that affect both pig and human health.

Fresh pig manure has a strong odor but the most dangerous gases develop as manure decomposes. The key gases are hydrogen sulfide, methane, ammonia, and carbon dioxide. Hydrogen sulfide is the most lethal. It is heavier than air and collects near the manure surface. At low concentrations it smells like rotten eggs. At higher concentrations it deadens your sense of smell, which makes it especially dangerous. Agitation releases these gases rapidly. That is why agitation and pumping are the highest risk times for pit gas exposure.

The nutrient content of pig manure varies with diet, age of pigs, and how the manure is stored. A typical finishing pig produces about 1.5 gallons of manure per day. A sow with a litter produces about 3 gallons per day. These numbers change with feed formulation and water use, so you should test your own manure rather than rely on book values.

The form of nitrogen in pig manure is mostly ammonium. This is the form plants can use readily, but it is also the form that volatilizes into ammonia gas. How you store and apply manure determines how much nitrogen you keep. Injection or immediate incorporation preserves nitrogen. Broadcasting on the surface without incorporation loses a large share.

Phosphorus in pig manure is more stable than nitrogen. It does not volatilize, but it can move with soil erosion or runoff if manure is overapplied. Potassium behaves differently again. It is highly soluble and stays available to plants, but it can leach in sandy soils.

Types of Swine Manure Management Systems

There is no single best system. The right choice depends on your barn design, herd size, climate, labor availability, and the land base you have for application. The main categories are liquid systems, solid systems, and semi-solid systems. Each has multiple variations.

Deep Pit Systems

Deep pits are the most common system in large confinement operations. The pit is built directly under a slatted floor. Manure drops through the slats into the pit below and stays there for months. Pit depth is typically 8 feet or more. Storage capacity ranges from 6 to 12 months depending on pit volume and animal numbers.

Deep pits work well with mechanical ventilation. The pit is part of the barn structure, so it does not require separate transfer pipes or pumps during normal operation. You pump the pit out one to two times per year, usually in spring and fall before crop application.

The main advantages are low daily labor, low water use, and good nutrient retention if you agitate and inject properly. The main disadvantages are the upfront cost of construction and the gas risk during agitation. Deep pits also require careful ventilation design because pit gases can migrate into the animal living space.

Pull Plug Systems

A pull plug system is a shallow pit under slatted floors. The pit holds manure for 7 to 30 days, then you pull a plug and the manure drains by gravity into an underground pipe that carries it to a larger outside storage structure. Some systems use a valve instead of a plug.

Pull plug systems reduce gas buildup inside the barn because manure does not accumulate for long periods. They also allow you to move manure to a central storage location, which may be more convenient for application. The downside is that you need a second storage structure, and you must manage the transfer carefully to avoid clogs.

Flush Systems

Flush systems use water or recycled lagoon liquid to wash manure from shallow gutters under slatted floors. A tank or pump releases a wave of water that carries manure through the gutter to a collection point or lagoon. Flush systems are common in warm climates and in barns with large pig numbers.

Flush systems keep the barn cleaner and reduce ammonia levels in the air. They also reduce pit gas hazards inside the barn. However they use large amounts of water. The resulting manure is very dilute, which increases pumping and application costs. You also need a reliable water supply and a well-designed gutter system to prevent solids from settling.

Lagoon Systems

Lagoons are earthen basins that store and treat manure. They are common in the southern United States and other warm regions. Manure is flushed or pumped into the lagoon, where bacteria break down solids. The liquid is then applied to crops, often through irrigation.

Lagoons require a large land area and warm temperatures to work properly. They do not work well in cold climates because bacterial activity slows dramatically in winter. They also produce strong odors, so they need adequate setbacks from neighbors. Nitrogen losses are high in lagoons, which reduces the fertilizer value of the manure.

Bedded Pack Systems

Bedded pack systems keep pigs on a thick layer of bedding such as straw, wood shavings, or cornstalks. The bedding absorbs urine and mixes with manure. The pack is removed periodically and composted or spread directly on fields.

Bedded packs work well in cold climates because the decomposing bedding generates heat. They also produce a solid manure that is easier to handle with a front-end loader and spreader. The main drawbacks are the labor and cost of bedding, the larger space requirement per pig, and the potential for ammonia buildup if the pack is not managed well.

There are several bedded pack variations. The conventional bedded pack is cleaned out completely between groups. The deep bedded pack accumulates over multiple groups. The compost bedded pack is aerated regularly to encourage aerobic decomposition. Each variation has different bedding requirements and management intensity.

Slurry Systems with Outside Storage

Slurry systems combine underfloor pits with periodic transfer to an outside storage structure. The underfloor pit is shallow, often 2 to 4 feet deep. Manure is scraped or drained to a collection sump, then pumped to an aboveground tank or earthen storage.

This system gives you the convenience of slatted floors with the safety and capacity of outside storage. It also makes agitation easier because you can agitate the outside tank with a chopper pump. The main cost is the additional storage structure and the pumping equipment.

Design Considerations for Manure Storage

The storage structure is the heart of your manure management system. Its size, construction, and location determine how much flexibility you have in application timing and how much risk you carry.

Sizing Storage for Your Operation

Storage must hold all manure produced between application windows. In most climates, you need at least 6 months of capacity. Many operations aim for 9 to 12 months so they can avoid spreading on wet or frozen ground.

To calculate required capacity, multiply the number of pigs by the average manure production per pig per day, then multiply by the number of days of storage you want. Add an allowance for wash water, spilled water, and rainfall if the storage is open. A typical finishing barn with 1,000 pigs will produce roughly 1,500 gallons per day. Over 180 days that is 270,000 gallons. Your storage must also account for the fact that you cannot pump the last few inches from the bottom.

It is better to oversize than undersize. Running out of storage capacity forces you to spread at the wrong time, which damages soil and invites complaints. Oversizing costs more upfront but gives you flexibility for years.

Pit and Tank Construction

Concrete is the standard material for underfloor pits and most outside storage. It must be reinforced and sealed to prevent leakage. A leaking pit contaminates groundwater and can create structural problems. Hire an engineer to design the pit walls and floor, especially for deep pits.

Earthen storages are cheaper but require careful site selection. The soil must have low permeability. If the soil is sandy or fractured, you need a liner. Clay liners, synthetic liners, or concrete liners are options. Check your local regulations because many areas require a professional liner and groundwater monitoring.

Aboveground steel tanks are another option. They are durable and easy to inspect, but they cost more than earthen storage. They also need corrosion protection and a secure foundation.

Location and Setbacks

Manure storage must be located away from wells, streams, and property lines. Typical setbacks are 50 to 150 feet from wells and 100 feet or more from streams and neighbors. Your local regulations may be stricter. Check with your extension office or environmental agency before you finalize a site.

Consider prevailing winds when you site storage. A storage structure upwind of your own house or a neighbor creates daily odor problems. Trees and berms can help, but they do not replace adequate distance.

Safety Features

Every manure storage structure needs safety features. Pits need a secure cover or grate over any access point. Outside storage needs fencing to keep children and livestock out. Warning signs should be posted at all entries.

Ventilation is essential for underfloor pits. The pit air space must be connected to the barn ventilation system so gases are exhausted rather than accumulating. Some systems use separate pit fans that run continuously or on timers.

Manure Transfer and Pumping Equipment

You cannot manage manure without moving it. The equipment you choose depends on the system type and the distance to your storage or application site.

Pumps

The main pump types are centrifugal, progressive cavity, and chopper pumps. Centrifugal pumps handle thin liquids well but struggle with thick manure and solids. Progressive cavity pumps move thick slurry smoothly and are good for long distances. Chopper pumps have blades that break up solids and are ideal for agitating pits before pumping.

Match the pump to your manure characteristics. Thick manure from a deep pit needs a chopper pump or a progressive cavity pump. Thin liquid from a flush system can use a simpler centrifugal pump. Oversizing a pump wastes energy and can cause excessive agitation.

Piping and Valves

Underground pipe carries manure from the barn to storage. Use pipe sized for the flow and slope it so it drains completely. A pipe that holds stagnant manure will clog and corrode. Install cleanouts at regular intervals so you can clear blockages.

Valves let you control flow and isolate sections for maintenance. Use gate valves or knife valves designed for slurry. Ball valves clog easily with manure. Install valves in accessible locations, not buried where you cannot reach them.

Scrapers

Some barns use mechanical scrapers instead of slatted floors. A scraper runs along a channel and moves manure to a collection point. Scrapers reduce the airspace under the floor, which cuts ventilation needs and gas risk. They also produce a thicker manure that is easier to handle.

Scrapers require regular maintenance. The blades wear, the drive chains stretch, and the channels can clog. Plan for daily inspection and periodic replacement of wearing parts.

Ventilation and Gas Management

Manure management and ventilation are inseparable. The gases produced by decomposing manure can harm pigs and kill people. A well-designed ventilation system removes these gases before they reach dangerous levels.

Understanding Pit Gases

Hydrogen sulfide is produced when bacteria break down manure without oxygen. It is heavier than air, so it settles in low areas. At 10 parts per million it causes eye irritation. At 100 parts per million it deadens your sense of smell. At 500 parts per million it can cause death within minutes.

Ammonia is lighter than air and irritates the respiratory tract of pigs and people. High ammonia levels reduce feed intake and growth in pigs. Methane is explosive at concentrations between 5 and 15 percent. Carbon dioxide displaces oxygen and causes suffocation in confined spaces.

Ventilation Design

The ventilation system must move air through the barn and remove gases from the pit headspace. In colder climates, minimum ventilation rates are set to control moisture and gases without chilling the pigs. In warmer weather, higher rates keep pigs cool.

Pit ventilation is a separate consideration. Some designs draw air down through the slats and exhaust it from the pit. Others exhaust pit air directly through dedicated fans. The key is that pit air does not mix with the pig living space.

Gas Monitoring and Safety Protocols

Install gas monitors in barns with underfloor pits. Monitors should alarm at hydrogen sulfide levels above 10 parts per million and ammonia above 25 parts per million. Place sensors near the pit surface and in the pig living space.

Never enter a pit or a manure storage structure without testing the air first. Use a multi-gas detector that measures hydrogen sulfide, methane, oxygen, and carbon dioxide. If the alarm sounds, leave immediately. Do not attempt to rescue someone inside a pit without proper breathing apparatus and a safety harness. Most manure pit deaths involve multiple victims because untrained rescuers enter and are overcome.

Agitation is the most dangerous time for gas release. Agitate only when you have good ventilation and when people are out of the barn. Open all doors and run fans at maximum. If possible, agitate from outside the barn using a pump that reaches through a wall port.

Nutrient Management Planning

Manure is a fertilizer resource, not just a waste product. A good nutrient management plan turns your manure from a liability into a cost-saving asset.

Testing Manure

Test your manure at least once per year, and more often if you change feed or water systems. Take samples during agitation so the sample represents the whole storage. Send samples to a certified laboratory for analysis of nitrogen, phosphorus, potassium, and dry matter.

Book values are a starting point but they are not reliable for your specific operation. Diet, water wastage, storage duration, and climate all change nutrient content. A manure test costs far less than the value of the nutrients you are managing.

Calculating Application Rates

Apply manure at rates that meet crop needs without exceeding them. The limiting factor is usually phosphorus or nitrogen, depending on your soil test levels. If soil phosphorus is already high, apply based on phosphorus and supplement with commercial nitrogen if needed.

To calculate a rate, you need the manure nutrient content, the crop nutrient requirement, and the soil test results. Your extension office or a certified crop adviser can help with the math. Many states have manure application calculators that simplify the process.

Timing and Application Methods

Apply manure when crops can use the nutrients. In most regions, this means spring before planting or after harvest in the fall. Avoid application on frozen ground, snow-covered ground, or saturated soil because runoff risk is high.

Injection places manure below the soil surface and eliminates most odor and nitrogen loss. Aeration and shallow incorporation are less effective but better than surface broadcasting. If you must broadcast, incorporate within 24 hours to reduce ammonia loss.

Step-by-Step: Managing a Deep Pit System

This section walks through the yearly cycle for a typical deep pit system. Adjust the timing to your climate and crop schedule.

Step 1: Pre-Spreading Inspection

Two to three weeks before you plan to spread, inspect the entire system. Check the pit for cracks, the pump for wear, and the application equipment for leaks. Confirm that the storage level is where you expect it. Walk the fields where you plan to spread and note wet areas or tile outlets.

Step 2: Arrange for Testing

Contact your laboratory and arrange for manure sampling. Plan to sample during agitation so the results reflect the full pit. If you are hiring a custom applicator, confirm that they have current certification and liability insurance.

Step 3: Agitate the Pit

Agitation is the step that requires the most care. Begin with the pit at its normal level. Do not add water before agitation unless the manure is extremely thick. Start the pump and agitate in one corner, then move systematically across the pit. Agitate long enough to suspend solids but not so long that you release excessive gas.

Keep people and animals out of the barn during agitation. Run all ventilation fans at maximum. If you have a pit fan, run it continuously. Watch for signs of gas release such as odor changes or pigs coughing.

Step 4: Pump and Spread

Pump the manure into your spreader or through an umbilical hose to the field. Work from the far end of the field toward the storage so you do not drive over freshly applied manure. Apply at the planned rate, using a flow meter or a calibrated spreader.

Step 5: Incorporate or Inject

If you are broadcasting, incorporate the manure as soon as possible. The sooner you incorporate, the more nitrogen you save and the less odor you produce. Injection eliminates the need for a separate incorporation pass.

Step 6: Clean Up and Record

After spreading, clean the pump and equipment. Rinse spill areas and check that no manure entered a waterway. Record the date, volume applied, field location, manure test results, and weather conditions. Keep this record in a file for at least five years.

Common Mistakes in Swine Manure Management

Even experienced farmers make errors. Here are the most common problems and how to avoid them.

Underestimating Storage Needs

The most expensive mistake is running out of storage. When the pit is full and the ground is wet, you have no good options. You either spread in bad conditions or pay to haul manure off the farm. Build more storage than you think you need.

Skipping Manure Testing

Manure nutrient content varies widely. Applying without a test means you either underapply and lose yield or overapply and waste money or create environmental risk. One test per year is the minimum.

Poor Agitation

Some operators skip agitation or do it too quickly. The result is a thick layer of solids left in the pit and thin liquid applied to fields. This wastes nutrients and creates a future clogging problem. Agitate until the manure is uniform throughout.

Ignoring Safety Protocols

Complacency kills. A farmer who has pumped the pit for 20 years without incident may skip the gas test or enter the pit without a harness. The one time conditions are different, the result is fatal. Follow the safety protocol every time.

Spreading on the Same Fields

Applying manure to the same fields year after year builds up phosphorus and potassium beyond crop needs. Rotate fields and use soil tests to guide where you spread. If you do not own enough land, work out a manure sharing arrangement with neighbors.

Forgetting to Calibrate Equipment

A spreader that is not calibrated applies a different rate than you think. Calibrate at the start of each season and whenever you change equipment or manure type.

Decision Thresholds: When to Change Your System

Your manure system should evolve as your operation changes. Consider a major change when you hit any of these thresholds.

You Cannot Empty Storage in the Application Window

If you regularly find yourself spreading in poor conditions or hauling manure off farm because you cannot empty storage in time, you need more capacity or a different system. Calculate your actual application window and compare it to your storage capacity.

Odor Complaints Are Recurring

Repeated complaints from neighbors mean your current system is not working for your location. You may need to switch from surface broadcasting to injection, or from a lagoon to a covered storage. Odor complaints can lead to legal action and local ordinances that restrict your operation.

Gas Incidents Occur

Any gas event, even a near miss, is a signal to change. Add pit ventilation, install gas monitors, or switch to a system that removes manure more frequently. Do not wait for a serious injury.

Your Herd Is Expanding

Expansion changes your manure volume and your nutrient balance. A system that worked at 500 sows may fail at 1,000. Recalculate your storage needs and land base before you add animals.

Regulations Change

Manure regulations are tightening in many regions. New rules may require covered storage, groundwater monitoring, or different application methods. Stay informed through your extension office and state agency. Plan for regulatory changes before they are forced on you.

Monitoring and Recordkeeping

Good records make you a better manager and protect you in disputes. Develop a simple system and use it consistently.

Daily Checks

Walk the barn daily and check the manure system. Look for plugged drains, leaking pipes, and unusual odors. Check that pit fans are running. Note anything unusual in a logbook or phone app.

Weekly Checks

Check storage levels once per week. Record the depth or level in a notebook. A sudden increase may indicate a water leak. A decrease without pumping means a leak in the storage.

Seasonal Checks

Inspect the entire system twice per year, before spring and fall application. Check pit walls for cracks, pump impellers for wear, and hoses for leaks. Test gas monitors and replace sensors as needed. Calibrate application equipment.

Application Records

For each manure application, record the date, field, crop, application method, volume or rate, manure test results, and weather. Note any unusual conditions such as wet spots or tile blowouts. These records are essential for nutrient planning and for defending your practices if a complaint arises.

Financial Records

Track the cost of manure management including pumping, hauling, application, and any custom hire. Compare these costs to the fertilizer value of the manure. This analysis shows whether your system is cost effective and helps you budget for improvements.

When to Call a Veterinarian or Extension Agent

Most manure management problems are not emergencies, but some situations require professional help.

Call a Veterinarian When

Pigs show respiratory signs that coincide with manure handling. Coughing, labored breathing, or reduced feed intake after agitation or pumping may indicate gas exposure. A veterinarian can assess the pigs and help you adjust ventilation or handling practices.

Sudden death in pigs with no other explanation may be gas related. If several pigs die at once, especially during or shortly after agitation, treat it as a gas event. Get people out of the barn, ventilate, and call your veterinarian.

Call an Extension Agent When

You are designing a new system or major renovation. Extension agents have access to current design standards and can connect you with engineers who specialize in manure systems.

You need help interpreting manure tests or developing a nutrient management plan. Extension specialists can run the calculations and help you match application rates to crop needs.

You are considering a different manure system and want an unbiased comparison. Extension agents do not sell equipment, so their advice is impartial.

You have questions about regulations or permit requirements. Extension agents stay current on state and federal rules and can direct you to the right agency.

Call a Regulatory Agency When

You suspect a leak from your storage. If you think manure is entering groundwater or surface water, report it immediately. The agency would rather help you fix the problem than discover it later.

You have a spill. Minor spills can be cleaned up on your own, but any spill that reaches a waterway must be reported to your state environmental agency. Check your state rules for reportable quantities.

Manure Management for Different Barn Types

The barn type shapes your manure options. Here are the main barn configurations and how they interact with manure systems.

Wean to Finish Barns

Wean to finish barns hold pigs from weaning to market weight. These barns have a continuous population with groups entering and leaving at intervals. Manure volume is relatively steady, but pig size changes the amount produced.

Deep pits work well for wean to finish barns because they require little daily labor. Pull plug systems also work if you have outside storage. Flush systems are less common because the dilute manure increases application costs.

Farrowing Barns

Farrowing barns have sows with litters. Manure production per sow is higher because of the added piglets. The barn layout with crates and heat lamps makes some systems difficult to install.

Deep pits and pull plug systems both work in farrowing barns. The key is to keep the area around the sow clean and dry. Some producers use a scraper system in the alley behind the crates.

Gestation Barns

Gestation barns house sows in groups or stalls. Manure production is steady and predictable. The system choice depends on the flooring. Slatted floors allow pits or pull plugs. Solid floors with bedding require a bedded pack system.

Finishing Barns

Finishing barns are the most common type in large operations. They hold growing pigs from about 50 pounds to market weight. Manure volume increases as pigs grow, so the system must handle variable daily production.

Deep pits are the standard choice. Pull plug and flush systems also work. The decision depends on climate, water availability, and whether you have outside storage.

Hoop Barns and Low Cost Housing

Hoop barns use bedded packs on a concrete or dirt floor. They are cheaper to build than confinement barns but require more labor for bedding and cleaning. The manure is solid and can be composted or spread directly.

Hoop barns work best in cold climates and for smaller operations. The bedded pack provides heat in winter. The main challenge is managing moisture. A wet pack produces ammonia and odor, so you need good ventilation and enough bedding.

Odor Control Strategies

Odor is the most common reason for neighbor complaints and local restrictions. A comprehensive odor control plan addresses the source, the storage, and the application.

Source Reduction

Diet manipulation can reduce odor. Lowering crude protein and adding synthetic amino acids reduces nitrogen excretion. Some feed additives claim to reduce odor, but results vary. Work with a nutritionist to balance odor control with feed cost.

Water management also matters. Fix leaking drinkers and reduce wash water volume. More water means more dilute manure, which increases odor and application cost.

Storage Management

Covered storage is the most effective way to control storage odor. Flexible covers, rigid covers, and floating covers all reduce emissions. Covers also keep rain out, which reduces volume and application cost.

If you cannot cover the storage, manage the surface. A natural crust on a lagoon reduces odor but can interfere with pumping. Some producers use straw or other materials to encourage crust formation.

Application Practices

Injection is the most effective application method for odor control. It places manure below the soil surface where odor is trapped. Shallow incorporation within 24 hours of application is the next best option.

Timing matters as much as method. Avoid spreading on weekends, holidays, or evenings when neighbors are outside. Avoid spreading before rain, which can carry odor and nutrients off field.

Community Relations

Talk to neighbors before you have a problem. Let them know when you plan to spread and offer to spread at times that work for them. A neighbor who understands your operation is more tolerant of occasional odor. A neighbor who hears about your operation through the newspaper is not.

Environmental Compliance and Regulations

Manure management is heavily regulated in most pig producing areas. The exact rules vary by state and by size of operation, but the general framework is consistent.

Concentrated Animal Feeding Operations

Large operations may be regulated as Concentrated Animal Feeding Operations or CAFOs under the Clean Water Act. CAFOs require a National Pollutant Discharge Elimination System permit. The permit requires a nutrient management plan and regular reporting.

The threshold for CAFO regulation depends on animal numbers and whether the operation discharges into waters of the United States. Check with your state environmental agency to determine if you need a permit.

State and Local Rules

Most states have their own manure regulations that are stricter than federal rules. These cover storage construction, setback distances, application rates, and recordkeeping. Some counties and townships have additional ordinances.

Work with your extension office and state agency to understand the rules that apply to you. Ignorance of the rules is not a defense. Fines for manure violations can reach tens of thousands of dollars.

Nutrient Management Plans

A nutrient management plan is a written document that outlines how you will use manure and other nutrient sources. It includes soil tests, manure tests, crop rotation, and application rates. The plan must be updated regularly and kept on file.

Even if you are not required to have a plan, developing one is good practice. It forces you to think through your nutrient balance and helps you avoid overapplication.

Economic Considerations

Manure systems are expensive to build and operate. A clear understanding of the economics helps you make sound decisions.

Capital Costs

Deep pits add significant cost to a new barn. The concrete, excavation, and reinforcing steel can add 15 to 25 percent to the barn cost. Outside storage adds another significant expense. Earthen storage is cheaper than concrete or steel, but it requires more land.

Operating Costs

The main operating costs are labor, energy, and equipment maintenance. Deep pits have low daily labor but high agitation and pumping costs. Flush systems have higher water and energy costs. Bedded packs have high bedding costs but lower pumping costs.

Fertilizer Value

Manure has real value as fertilizer. A 1,000 head finishing barn produces manure with nitrogen and phosphorus worth thousands of dollars per year. The value depends on application method. Injection preserves more nitrogen than broadcasting.

Custom Application vs. On Farm

Many producers hire custom applicators rather than owning equipment. Custom application avoids capital costs and maintenance, but it reduces your control over timing and method. Compare the costs carefully, including the value of your time.

Manure Management Plan Template

A written plan keeps you organized and helps you train employees. Use this template as a starting point.

Section 1: Operation Information

List the farm name, owner, address, and contact information. Describe the barn types, pig numbers, and production schedule.

Section 2: System Description

Describe your manure system in detail. Include pit dimensions, storage capacity, pump types, and application equipment. Include a diagram or map.

Section 3: Storage Capacity

Calculate your manure production and storage capacity. Show that you have at least 6 months of capacity, and ideally more.

Section 4: Application Plan

List your fields, crops, soil tests, and planned application rates. Include a map showing field locations and setbacks.

Section 5: Safety Procedures

Describe your gas monitoring, ventilation, and entry procedures. List the safety equipment on hand and the training requirements for employees.

Section 6: Emergency Procedures

Describe what to do in a spill, a gas incident, or a storage failure. Include phone numbers for your veterinarian, extension agent, and regulatory contacts.

Section 7: Recordkeeping

Describe your record system for manure tests, application records, and maintenance. List the records you keep and how long you keep them.

Future Trends in Swine Manure Management

The industry is moving toward systems that recover value from manure and reduce environmental impact. Keep these trends in mind as you plan for the future.

Anaerobic Digestion

Anaerobic digesters use bacteria to break down manure and capture methane for energy. The digester produces biogas that can generate electricity or heat. The remaining digestate is a more stable fertilizer with less odor.

Digesters are expensive and work best on large operations with consistent manure supply. They also require careful management to maintain the right temperature and bacterial balance.

Nutrient Recovery

New technologies can extract phosphorus and nitrogen from manure and concentrate them into saleable products. These systems reduce the land area needed for application and create a new revenue stream. The technology is still developing and costs are falling.

Precision Application

GPS guided application equipment can vary manure rates across a field based on soil tests and yield maps. This precision reduces overapplication and improves crop response. The equipment costs more but pays for itself on large acreage.

Covered Storage with Gas Capture

Some operations are covering storage structures and capturing the gases for energy or odor control. This approach reduces emissions and can generate revenue. The cost of covers and gas handling equipment is significant.

Frequently Asked Questions

How often should I empty my deep pit?

Most operations pump deep pits one to two times per year. The timing depends on storage capacity and crop application windows. The goal is to empty the pit when crops can use the nutrients, usually in spring and fall. Never let the pit get so full that you are forced to spread in poor conditions. Check the pit level weekly and plan your pumping schedule well in advance.

What is the safest way to agitate a manure pit?

Agitation releases dangerous gases, so safety is critical. Start by moving all people and animals out of the barn. Open all doors and run ventilation fans at maximum. Use a gas monitor to check the air before and during agitation. Agitate slowly and avoid creating a vortex that pulls air into the pump. If you smell gas or feel dizzy, stop agitation and leave the area immediately. Never enter a pit during or shortly after agitation.

How do I know how much manure my pigs produce?

Manure production varies with pig size, diet, and water use. As a planning figure, a finishing pig produces about 1.5 gallons per day and a sow with litter produces about 3 gallons per day. To get accurate numbers for your operation, measure the volume you actually pump and divide by the number of pig days. Track this over several pumping events to establish your own production rate.

Can I spread manure on frozen ground?

Spreading on frozen ground is risky because runoff can carry manure into waterways. Many states restrict or prohibit winter spreading. If you must spread in winter, use injection or immediate incorporation, stay far from streams and tile inlets, and only spread on gentle slopes. The best approach is to build enough storage capacity to avoid winter spreading altogether.

What is the difference between a pull plug and a deep pit system?

A deep pit stores manure under the barn for months and is pumped out one to two times per year. A pull plug system uses a shallow pit that is drained every 7 to 30 days into an outside storage structure. Pull plug systems reduce gas buildup in the barn and allow more control over storage, but they require a second storage structure and more piping.

How do I reduce odor from my manure system?

The most effective odor control is injection during application. For storage, covers are the best option. You can also reduce odor at the source by adjusting diet and fixing water leaks. Timing matters too. Spread when weather will disperse odor quickly and avoid spreading before rain or on calm evenings. Talk to your neighbors and let them know your schedule.

Do I need a nutrient management plan?

Most large operations are required to have a written nutrient management plan. Even if you are not required to have one, developing a plan is good practice. The plan helps you match manure application to crop needs, avoid overapplication, and document your practices if a complaint or inspection occurs. Your extension office can help you develop a plan.

What should I do if I suspect a manure leak?

If you suspect a leak from your storage, act immediately. Stop using the storage and locate the source of the leak. If manure is reaching a waterway, call your state environmental agency right away. In most states, you are required to report any discharge that reaches surface water. Early reporting shows you are acting responsibly and can reduce penalties.

Related Farming Guides

This section will be populated with links to related farming guides on pig housing, ventilation, and nutrient management. Check back for updated content.

Related Clinical & Scientific Guides

• Pig Enrichment Programs and Behavior Monitoring
• Swine Handling Facility Design for Safe Pig Movement
• Swine Feeding Management for Grow-Finish Pigs

References

• National Pork Board: https://www.pork.org/
• USDA APHIS Swine Health: https://www.aphis.usda.gov/livestock-poultry-disease/swine
• FAO Pig Production: https://www.fao.org/pig-production-and-products/en/
• FAO Animal Production and Health: https://www.fao.org/animal-production/en/
• WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/

This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.