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Articles: Animal Wastes and Their Management
Posted by: JimEdwards on Sep 21, 2004 - 11:46 PM
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By Syed Hassan Raza
Department Of Livestck Mangement
Agriversity Faisalabad 38000
WHAT IS WASTE?
ANIMAL WASTES:
i) Manure refers to feces and urine.
ii) Waste refers to manure with added bedding, rain, soil, etc. It also refers to milk house or washing waters not
particularly associated with manure. Livestock wastes also typically include hair, feathers, and other debris.
i) MANURE
Manure with up to 15% solids has liquid handling characteristics. Extra water must often be added to dilute the manure for handling as a liquid. Wastes with up to 4% solids can be handling with irrigation or flushing equipment. Manure with 4%-15% solids is semi-liquid slurry that can be handled as a liquid but may need special equipment for pumping.
A general range of solids content for manure without bedding is:
20%-25% solids: stiff; some drying or liquid separation has taken place for most manure.
15-20% solids: semi-liquid, quite thick slurry.
5-15% solids: liquid slurry.
0-5% Solids: irrigation or flushing consistency.
IMORTANCE:
A complete waste disposal system is no longer a luxury in a livestock business-it is a necessity. Care full waste management is needed to:
* Maintain good animal health through sanitary facilities.
* Avoid pollution of air and federal regulations.
* Balance capital investment, labor, and nutrient use.
MANURE GASES CAN KILL
Hydrogen sulfide poisoning or lack of oxygen kills. Enter in a manure storage only after it has been well ventilated; wear self- contained breathing tanks; and have a safety rope attached and at least two people standing be to pull you out at the first sign of dizziness.
Methane gas can accumulate in covered pits, creating explosive conditions. Do not introduce a spark or flame unless the pit has been well ventilated.
CONTROLLING ODORS
To control odors, locate buildings and manure storage where prevailing summer winds and air drainage downhill on calm nights will carry odors away from you or your neighbor. In most of the Midwest, locate manure storages to the north or east of residences. There is no "safe" separation distance, but try to locate your facilities at least 1/2 mile from neighbors or farther if you have a large operation, open lot, or lagoon.
Open lots have more odor than environmentally controlled buildings. Frequent scraping reduces odor production.
Locate ventilation fans high on walls or place buildings on high ground to disperse ventilation exhaust odors.
Frequent removal of manure and proper pit ventilation reduce odor within the building. Filtering dust particles, which carry odors, also reduces some noxious odors.
Lagoon odors can be reduced with proper dilution and loading but can still be severe during spring and fall when lagoon contents change temperatures and turn over.
Cover wastes to minimize odor release. Covered storage may be a floating crust or a concrete lid. Immediate plow down or chisel infection of wastes decreases odors from land applications.
Chemical treatment can reduce odors. However, many treatments require relatively large amounts of chemicals, have some disadvantageous results, and are at best temporary cures to odor problems.
Several collection methods are possible. Some systems combine collection and storage, such as a built up manure pack or slotted floors over a liquid pit. In selecting a collection system, consider:
* Facility type.
* Labor requirements.
* In vestment.
* Total waste handling system.
SLOTTED FLOORS
Slotted floors rapidly separate an animal from its manure. Opening size and slat width depend on manure properties and experience with slipping, foot injury, and other animal responses. See Table 702-1.
Tapered slats (greater top than bottom width) tend to pass wastes better than uniform- width slats. For easy commercial slat installation, build the opening for the slat 1/2"-1 wider than the length of the slats to allow for variation in construction work. Where slats are parallel to a wall or partition, leave a 2"(3" for cattle) space to avoid solids buildup.
In partly slatted buildings, place slats parallel to the long dimension of rectangular pens. Try to place slats parallel to natural traffic flow patterns, so animals walk along rather than across slats to minimize foot injury.
Concrete slats are the most durable and work well for large animals. They can be purchased precast, precast at the lowest initial cost and shortest life. Wood wears, warps, and is chewed by hogs, leaving irregular spacings, and can become slick with use. Manufactured slotted floor systems of steel, aluminum, and plastic are more uniform for more accurate spacing and smoother for easier cleaning. They may be easier to handle, install, and replace than concrete, but can be more expensive. When selecting slats, consider initial cost, predicted life, intensity of use (wear rate), strength, corrosion, fire, noise, replacement cost, and most importantly, the type of animal housed. Younger animals require cleaner floors. Make slats stable; twisting flexing, or shifting may cause cracks in the slat material or slat coating or may catch or pinch animals.
LIVESTOCK BUILDING FLUSHING SYSTEMS
The quantity and composition of wastes produced influence livestock waste facility design. The properties of livestock waste depend upon several factors: animal species; ration digestibility, protein, and fiber content; animal age, environment, and productivity; and quantity of added bedding, soil, water, etc.
Animal producers generally have a choice of waste handling methods. Wastes are handled as either solids or liquids. Liquids can be handled with slotted floors, flushing systems, gravity flow gutters, or scraper system. Solids can be handled with manual or mechanical scrapers or front-end loaders.
The disposal method chosen depends primarily on whether the waste is liquid or solid. Solids are usually spread on fields with conventional spreaders. Liquids are usually spread on fields with thank wagons, applied with irrigating equipment, or digested in a lagoon before field spreading.
In flushing systems, a large volume of water flows from one end of a building to the other, down a sloped, shallow gutter.
The water scours manure from the gutter and removes it to a lagoon. Two types of flushing systems are used in livestock facilities:
* Open-gutter flushing for finishing and gestation buildings, dairy free stall alleys, and holding areas.
* Underslat flushing for swine and beef buildings.
FLUSH TANKS
Five types of flushing devices are:
* Automatic siphon tank.
* Tipping bucket.
* Trap door tank.
* Manual flush tank.
* Large volume pump.
Storage design varies by state because of climate and pollution control regulations. Use recommendations on size, location, construction, and maintenance with care.
Avoid locating unlined storages over shallow creviced bedrock or below the water table. If shallow bedrock is present, consult a qualified engineer or contact your board of health. Also avoid storage in gravel beds or other areas where serious leakage can cause ground water pollution.
Allow at least 100' between a water supply and the nearest part of a storage. Locate manure storages at least 50' from a milkhouse or milking parlor. Check with milk and health authorities for minimum spacing requirements. Consider all farmstead operations, building locations, and prevailing winds when planning storages.
Locate, size, and construct storages for convenient filling and emptying and to keep out surface runoff. Provide all- weather access.
STORAGE CAPACITY
Storage capacity depends on regulations, number and size of animals, amount of dilution by spilled and cleaning water, amount of stored runoff and desired length of time between emptying. Provide enough storage to spread manure only when field, weather, and local regulations permit. Post-harvest spreading saves time during busy spring planting activities. It also provides a chance for freezing and thawing during winter to lesson the effects of soil compaction from the spreading operation.
Plan for 10 to 12 mo storage capacity. Provide extra capacity for dilution water, rain snow and milking center waste.
If the storage receives only animal manure add dilution volumes of 10% for cattle and 20% for swine to account for waterer wastage, rain and snow. Add up to 60% dilution volume to the animal manure production if milking center waste, sow wash, or farrowing stall wash water enter storage. If the amount of additional water is unknown, plan for a total volume (manure plus dilution) equal to twice the animal manure production. Provide at least 1' of freeboard.
From 20%-60% of the storage volume may be needed for dilution water if the manure is for irrigation.
Storage capacity
(number of animals X daily manure production X desired storage time in days) + cleaning or leakage water + freeboard volume above lowest inlet opening.
WASTE HANDLING: HANDLING METHODS
LIQUID MANURE HANDLING:
Up to about 15% solids, manure has fluid handling characteristics. Up to about 4% solids, the waste can be handled as a liquid with irrigation or flushing equipment. From 4%-15% solids, the manure is semi-liquid and can be handled as a liquid, but equipment needs differ. Fibrous materials, such as bedding hair, or feed, can hinder manure pumping. Chopper pumps can cut fibrous materials for improved pumping. Piston manure pumps handle manure with bedding
LIQUID MANURE HANDLING
Livestock producers handle manure as a liquid for one or more of the following reasons:
* Liquid manure usually requires minimal time and labor, as it can be treated in lagoons or stored in pits, tanks, or earth storage’s until spread. Pits are concrete under- building storage and tanks are outside and usually separate from the building.
* Disposal of liquid manure can be postponed to fit field schedules, soil conditions, and expected rainfall, if the storage unit is properly sized.
* Objectionable odors, unsightliness, and fly problems can be controlled when wastes are stored in a covered storage.
(However, odors that occur from spreading can be more objectionable than those from solid manure.)
Handling liquid manure requires the following facilities and equipment:
* Scrapers, gutters, slotted floors, or drains to move the wastes into storage or treatment.
* A storage or treatment unit to which needed water can be added.
* Pumps, agitators, or augers to stir and remove the liquid manure.
* Tanker or irrigation equipment and land to dispose of the manure.
SOLID MANURE HANDLING
Wastes with 20% or more solids can usually be handled as a solid. Solid manure results from catching and holding manure in bedding, or from allowing the liquids to run off, leaving the solids to be handled separately.
Wastes with 20% or more solids can usually be handled as a solid waste characteristics very with the animal, ration, amount and type of bedding, time of year, and the amount of liquids that have been separated.
Most solid manure spreaders are box- type. Others include flail- type spreaders, dump trucks, earth movers, or wagons. A spreader should distribute wastes uniformly. Front- end loaders, scrapers and blades, and several mechanical systems transport solid wastes, but they are not usually used for spreading.
Flail- type spreaders usually have a shaft mounted near the open top and parallel to the main axis of the tank. Chain flails on this shaft throw the wastes out the side of the spreader as the shaft turns.
Box- type spreaders are pulled or mounted on trucks. Pull-types have 70 to 525 bu capacities. Flail-type spreader capacity is measured in tons -1 ton is about 27 bu. On spreaders under 110 bu capacity, the spreading mechanism is either ground or PTO driven. If ground driven, 2 or 4 drive wheels are used. PTO drives are used on larger spreaders. Truck-mounted box spreaders hold 175 to 525 bu. Spreader boxes are of steel or wood and should be watertight for road transport. Spreader mechanisms include paddles, flails, and augers. The feed apron, which moves the spreader, have moving front- end gates that push the wastes to the spreading mechanism.
Large spreader capacity reduces the number of trips to the field but may increase soil compaction. Calculate the number of trips from the amount of manure and spreader capacity.
HANDLING SOLID MANURE REQUIRES
* Solid floors that can be bedded or drained.
* A minimum of equipment.
* An area on which to spread the solids.
SUGGESTIONS
* Install sloping floors; locate waters where manure accumulation is desired; and keep pens full.
* Haul manure directly to fields whenever possible, but avoid spreading on frozen fields.
* When a stockpile is necessary, locate it for convenient access to spreader, out of natural drainage ways, and away from any water source. Divert surface water away from the storage area.
* Control runoff from stockpiles or lots.
ANIMAL WASTE UTILIZATION
Regardless of the storage, treatment, and handling methods for animal wastes, some end products remain. They are valuable resources for benefit or return. Or, they are unwanted wastes to be disposed of economically and efficiently. The end use of wastes often dictates the waste disposal system. Consider the pollution and nuisance potential of the disposal method along with economy, fertilizer value, etc. The cheapest method may not meet regulations or be acceptable to your neighbors.
Most operators utilize wastes for an economic return, or at least to minimize costs. Animal manure is most commonly a fertilizer and soil conditioner.
Other established or potential practices include:
* Irrigation with waste effluent to supplement water needs for crop production.
* Reuse of liquids to flush and transport manure.
* Use of processed solids as bedding or litter.
* Use of processed solids for off farm fertilizer, soil additive, or mulch.
* Salvage of energy from methane production.
* Reuse as feed ingredients for livestock, poultry, and aquatic life.
LAND APPLICATION
EFFECTS
Manure nutrients help build maintain soil fertility. Manure also improves tilth, increase water holding capacity, lessens wind and water erosion, improves aeration, and promotes beneficial organisms. When wastes include runoff or dilution water, they can supply water as well as nutrients to crop production.
The economic value of manure fertilizer is calculated from its available N, P, and K at commercial fertilizer prices.
These value change with the costs of fertilizer and handling.
Excess wastes can harm crop growth, contaminate soil, cause surface and ground water pollution, and waste nutrients.
While most soil have a tremendous capacity to absorb phosphorus, very high soil phosphorus levels can interfere with plant nutrition by inhibiting up take of metallic trace elements such as iron, zinc, and copper. When plant residue or manure is added to soil, there is an immediate and marked drop in O2 and an increase in CO2 in the soil air which can inhibit plant growth.
The carbon-nitrogen ratio (C/N) of applied wastes affects both microbial and plant growth. If a waste having a high C/N ratio, such as manure with a lot of bedding, is added to a soil, organisms decomposing the organic matter grow until available mineral and nitrogen is bound by the microorganisms. In the short run, nitrogen is unavailable for plant use and more chemical fertilizer may have to be added than before the waste application.
Heavy manure applications can increase soil salinity (salts) especially in arid regions where little or no leaching occurs. Salts can inhibit plant growth and depress yields. If salinity becomes a problem, consult a crop specialist.
Sodium and potassium can alter soil structure and reduce water movement rates. Field equipment, such as heavy manure wagons, compacts wet soils, alters soil structure, and reduces water movement. Yield reduction can result.
SURFACE AND GROUNDWATER QUALITY
Several diseases that infect both animals and man can be transmitted in water-borne livestock wastes. Land application can successfully interrupt infection cycles if water pollution is prevented.
Surface runoff contains pollutants, including plant nutrients, oxygen-demanding material, and some infectious agents.
Excessive nitrogen applications can cause nitrate pollution of water-the cause of infant cyanosis (blue babies) and perhaps chemical diarrhea.
Nitrogen in excess of crop requirements leaches through the soil once it is in the nitrate form. For local application rates to avoid ground water pollution, consult your state extension crop and soil specialist or the SCS. Reducing excess nitrogen without pollution is difficult.
Excess nutrients in surface water can cause algae blooms, impaired fisheries, fish kills, odors, and increased turgidity. Nutrients in runoff from land where manure was applied and incorporated in the summer are less than in runoff where no manure was applied. But large nutrient losses can occur in spring runoff from land where manure was applied on frozen ground.
NUTRIENT LOSSES DURING COLLECTION AND STORAGE
Housing and waste handling systems affect the nutrient composition of wastes. Bedding and water dilute manure, resulting in less nutrient value pre pound. Much nitrogen can be lost to the air an ammonia. Runoff and leaching in open losts can remove nutrients. But there is much less nitrogen loss from deep compost pits, liquid storage systems, or roofed feeding areas. See Table 707-1.
Phosphorus and potassium handling losses are negligible except for open lots or lagoons. About 20-40% of the phosphorus and 30% 50% of the potassium can be lost by runoff and leaching in open lots. However, much of the P and K can be recovered by runoff control systems such as settling basins and holding ponds. Up to 80% of the phosphorus and nitrogen is lost in lagoons and becomes unavailable when sprayed on land.
APPLICATION
-Manure is usually
* Broadcast (top dress) with plow down or disking.
* Broadcast with out plow down or disking
* Knifed (injection under the soil surface).
* Irrigated.
The greatest nutrient response follows land application and immediate incorporation into the soil. Plow down solid manure as soon as possible to minimize nitrogen loss and to begin release of nutrients for plant use. Injecting, chiseling, or knifing liquids into the soil minimizes odors and nutrient losses to the air and/or to runoff.
Nitrogen loss as ammonia from land is greater during dry, warm. Windy days than during humid or cold days. Ammonia loss is generally greater during the spring and summer months. Most losses occur in the first 24 hr after application, so incorporate manure first 24 hr after application, so incorporate manure into the soil as soon as possible.
Apply manure as near planting date as possible so more nutrients will be available to plants. While it may be more convenient to apply wastes in late fall or winter, 25% 50% of the total nitrogen can be lost from decomposition and leaching.
With liquid manure much nitrogen loss by leaching or denitrification can be stopped with a nitrification inhibitor. These products inhibit the action of certian soil bacteria that covert ammonium nitrogen to nitrate nitrogen. They are volatile compounds so immediate incorporation the soil in vital.
CROP NUTRIENT REMOVAL
Apply manure so nutrients added do not greatly exceed crop needs. Manure nutrients, especially nitrogen, are utilized more efficiently by grasses and cereals than by legumes. Legumes get most of their nitrogen from the air, so additional nitrogen is not usually needed.
For the greatest return, apply manure first to corn and small cereal grains, then to sorghum and forages, and finally to pasture.
With heavy manure applications, have your soil tested for fertilizer needs and nutrient imbalance. Adjust waste application rates for your soil conditions against soil tests for phosphorus and potassium to balance crop nutrient needs.
OTHER MANAGEMENT CONSIDERATIONS
* Check state and local regulations concerning land application times and rates.
* Surface apply animal wastes at least 100' from streams, ponds, open ditches, and inlets to tile lines.
* While ground is frozen, apply animal wastes to relatively level land remote from surface water.
* Avoid spreading liquid manure on water saturated soils where runoff is likely.
* For odor control, spread raw animal wastes frequently, especially during the summer; spread early in the day as the air is cooling and settling; and avoid days when the wind is blowing toward populated areas or when the air is still and seems to hang.
* Agitate or mix liquid wastes for removal of settled solids and uniform waste nutrient application to the land.
DR KHALID MAHMOOD SHOUQ (D.V.M)UAF
EDITOR IN CHIEF
THE VETERINARY NEWS & VIEWS WEEKLY
LIVESTOCK AND POULTRY INFORMATIONS NETWORK PAKISTAN
SECRETARY
THE WORLD'S POULTRY SCIENCE ASSOCIATION PAKISTAN BRANCH
www.pakissan.com
POSTAL ADDRESS
392-A,SAMANABAD FAISALABAD PAKISTAN 38070
TEL. 0092 41 665392,665352 FAX 0092 41 562853
E-MAIL
khalidshouq@hotmail.com
pakissan2002@yahoo.com
CELLULAR 0092 300 6620616
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