Posted on

does chicken manure have lots of weed seeds

Poultry Litter Application on Pastures and Hayfields

Poultry litter is commonly used as a fertilizer on pastures and hayfields in North Georgia. As the poultry industry expands to South Georgia, more litter will be available and its use in this region is expected to increase. Poultry litter is a good source of many nutrients. In fact, it is much like a complete fertilizer containing not only primary nutrients but secondary and micronutrients (Table 1). The fertilizer equivalent is typically about 3-2-2 (N-P2O5-K2O); however, the actual nutrient content depends on the type of bird, what the birds are fed, the number of growouts before the house is cleaned out, the feed efficiency, and how the litter is stored and handled. More information on nutrient variability in poultry litter can be found in “Maximizing Poultry Manure Use through Nutrient Management Planning” listed in the Further Information section.

Table 1. Average nutrient content of various types of poultry litter.
Constituent Broiler
Nitrogen 63 55 47
P2O5 55 57 59
K2O 47 47 46
Calcium 43 36 54
Magnesium 9 10 81
Sulfur 15 12 91
Manganese 334 362 340
Copper 319 313 366
Zinc 265 286 272
Data from the Agricultural and Environmental Services Laboratory, University of Georgia.


Not all of the nutrients in poultry litter are immediately available for plants to use. Most of the nitrogen in poultry litter is in an organic form (about 89%), but poultry litter also contains ammonium (about 9%) and a small amount of nitrate (about 2%). The inorganic nitrogen (ammonium and nitrate) can be immediately used by plants. Organic nitrogen is not available to plants until it is converted to ammonium or nitrate by microorganisms in the soil. Because this is a biological process, the rate of conversion depends on soil moisture and temperature. The conversion takes place over time with the largest release of nitrogen shortly after application if the soil conditions are favorable, i.e. moist and warm (above 50ºF). If conditions are extremely dry or cold, little or no nitrogen may be released. One advantage of poultry litter for pastures is that the slow conversion of organic to inorganic nitrogen distributes available nitrogen more evenly over the growing season.

Because there is ammonium in poultry litter, some of the nitrogen can be lost to the atmosphere after the poultry litter is applied. This process is called volatilization. Hot, dry and windy conditions favor the loss of ammonium through volatilization. If poultry litter is applied during extended hot, dry and windy conditions, almost all the ammonium form of nitrogen in the litter can be lost. Application of poultry litter before rain can help incorporate ammonium into the soil as the water infiltrates. However, litter application before large storms can cause a substantial loss of nutrients in surface runoff.

Nitrogen can also be lost through leaching. The nitrate form of nitrogen is mobile in the soil and can move below the root zone, particularly during the winter months when some forages are dormant and rainfall is high.

Due to these processes, only about 50 percent of the nitrogen in a ton of poultry litter is available for plants to use during the growing season when it is applied. Most of the nitrogen not taken up by forages in the first season is either lost to the environment or stabilized as soil organic matter. Very little “carryover” of nitrogen from poultry litter can be expected the second year after application.


Poultry litter is a good source of phosphorus, which is beneficial when soils are low in phosphorus, but can present environmental problems if the soil is already high in phosphorus. Most of the phosphorus will be available during the growing season when it is applied.

Since grasses normally require three or four times more nitrogen than phosphorus, and poultry litter contains almost equal amounts of both, using poultry litter to meet the nitrogen needs of the forage will cause an over-application of phosphorus. Phosphorus can quickly accumulate to high levels with overapplication (Figure 1). Phosphorus buildup is slower on hayfields where hay is being removed, than in pastures where it is returned to the soil in manure and urine (Figure 2). Research has shown 80 percent of phosphorus consumed by cattle in grass is returned to the pasture. High rates of poultry litter application and greater stocking rates can quickly increase the amount of phosphorus in the soil.

High phosphorus levels in the soil have been directly linked to water quality problems; consequently, use poultry litter carefully to supply the nutrient needs of the forage without creating environmental problems. Many farmers are using nutrient management plans to help them achieve these goals. Extensive information about nutrient management plans is available at the AWARE website (see Further Information section).

Soil testing should be conducted annually to monitor for phosphorus buildup in the soil. If soil test phosphorus from your soil test report is in the high to very high category, your local county agent should help determine the P Risk Index for your fields. The P Risk Index will indicate if the phosphorus levels in the soil and your management practices create a significant risk to nearby surface waters.

There are two common management alternatives to reduce risk. One option is to alternate the use of poultry litter with commercial fertilizer source of nitrogen. Another option is to apply poultry litter to meet the phosphorus needs of forage and to use commercial fertilizer to meet the nitrogen requirement. These practices can help reduce the water quality impacts of excess phosphorus in the soil. (See AWARE website in Further Information section).


Poultry litter is also a valuable source of potassium. Nearly 100 percent of the potassium in poultry litter will be available during the growing season when it is applied. Whether the amount of potassium available in poultry litter is adequate for your forage crop will depend upon the potassium level in the soil, the particular forage, whether the field is grazed or hayed, and, if grazed, the stocking rate.

Secondary and Micronutrients

Poultry litter is also a source of secondary nutrients such as calcium, magnesium, and sulfur as well as micronutrients such as copper and zinc. Studies have shown increased levels of copper, manganese, and zinc in the soils where poultry litter has been used for four to five years. Similar to phosphorus, copper and zinc can have detrimental effects if overapplied. Studies on metal uptake on various crops and forages, generally show low levels of metals in the forages even at high poultry litter application rates. Data from northwest Georgia indicated copper and zinc levels in bermudagrass hay after four years of poultry litter application (4 tons/acre) were within the recommended range for cattle nutrition.

Poultry litter can also contain other elements such as arsenic. In some parts of the country, arsenic is used in the poultry feed to help control internal parasites. Arsenic is usually toxic to plants before it reaches levels in the plant that would create a health problem for animals. Discussions of arsenic in poultry litter can be found in the references (see Further Information section).

Poultry Litter and Soil pH

Soil pH is considered a master variable because it is so important in controlling the availability of nutrients in the soil for plants to use. Most grasses have optimum yield and quality at a soil pH of 6.0. Since calcium carbonate (lime) is used in the feed rations of poultry, the litter can serve as a dilute liming material (about 1/10 strength of most agricultural limestones). Consequently, the use of poultry litter can help maintain soil pH and reduce the frequency of lime applications.

In the soils of northwest Georgia, poultry litter at the recommended application rate (4 tons/ac) for bermudagrass hay maintained soil pH at 5.76 after five years compared to 5.42 in the unfertilized plots and 5.18 in the plots receiving ammonium nitrate fertilizer. In northeast Georgia, the soil pH in hayfields receiving poultry litter for five years was 6.6 compared to 6.0 in a hayfield fertilized with inorganic fertilizer and limestone. Similar effects are likely in the sandy soils of South Georgia.

Although poultry litter can help reduce soil acidity, lime will likely still be needed. Because magnesium is generally lower in poultry litter than calcium, a dolomitic lime may be needed to supply this nutrient. Use your soil test results to determine the lime needed and whether dolomitic lime should be used.

Forage Yields

In general, forage yields with poultry litter are comparable to those with commercial fertilizer, assuming the poultry litter is applied at an equivalent nitrogen rate. In a grazing situation, you may be able to use a lower equivalent nitrogen application rate when using poultry litter as compared to inorganic fertilizer. In northeast Georgia, grazed bermudagrass pastures fertilized with poultry litter had the same productivity as those receiving inorganic fertilizer, although the poultry litter supplied about 30 percent less nitrogen (138 lbs/ac) than the inorganic fertilizer (200 lbs/ac). In a hayfield situation, the lower nitrogen application rate with poultry litter led to a 22 percent reduction in yield.

The use of poultry litter can affect forage growth patterns and mix of plant species that occur in the pasture. Tall fescue fertilized with poultry litter tends to have slightly higher growth in the summer and slightly lower growth in the spring and fall than fescue fertilized with spring and fall inorganic fertilizer applications. This is probably due to the slow release of nutrients over the growing season.

Several studies report that poultry litter use reduces the amount of clovers in mixed clover/fescue associations. This may be an important consideration for producers managing fescue toxicosis by dilution with clovers. The plant composition of bermudagrass pastures can also be altered by the use of poultry litter. After five years of poultry litter application, bermudagrass hayfields fertilized with poultry litter had a higher proportion of annual grasses and broadleaf weeds. This weed increase was not seen in the grazed bermudagrass pastures (Figure 3). Many producers report increases in weeds when using poultry litter. Studies indicate this is not due to weed seeds in the poultry litter but is due to the availability of nutrients over a longer period of time during the growing season. Many weed species germinate more readily when soil nutrient levels improve and compete well with forage species under these conditions.

Forage Quality and Animal Performance

Forage quality with poultry litter fertilization is generally similar to or better than that of commercial fertilizers though results will vary with the type of forage, management, and soils. A four-year study in northwest Georgia indicated that crude protein and total digestible nutrient content of bermudagrass hay fertilized with 4 tons/acre of poultry litter was similar to that fertilized with commercial fertilizer at a similar nitrogen fertilizer rate. The calcium, phosphorus, and potassium content of the poultry litter fertilized hay tended to be higher than the commercially fertilized hay. A West Virginia study in a mixed grass/clover pasture fertilized with poultry litter found increased crude protein and higher digestible nutrients as well as higher phosphorus and potassium contents than pasture fertilized with commercial fertilizer.

There are studies indicating forage grown with poultry litter may have higher sulfur content than comparable forage grown with commercial fertilizer. Because high sulfur content in forage can induce copper deficiency in cattle, producers should be aware of potentially higher sulfur content in forages fertilized with poultry litter. In Georgia, sulfur content of forage is assumed to be low because, in our high rainfall climate, sulfur tends to move rapidly through the soil profile. With the reports of high sulfur forages in the state, feeding a high copper mineral supplement (25,000 ppm) may be warranted in some cases to ensure cattle health.

Some studies also report lower magnesium contents in forage fertilized with poultry litter. Low magnesium concentrations relative to potassium can induce grass tetany. This is particularly common in nursing cows. There is anecdotal evidence of a higher occurrence of grass tetany with poultry litter use. Producers should feed magnesium supplements and monitor cattle intake regardless of whether or not poultry litter is applied to pastures to prevent this disease.

Cattle performance on pastures using poultry litter is typically good. In northeast Georgia, stocker cattle on tall fescue pastures fertilized with poultry litter had equivalent weight gain to those on fescue fertilized with inorganic fertilizer. However, seasonal weight gain was different. The cattle on pastures fertilized with inorganic fertilizer tended to have a greater weight gain in the autumn and winter. Cattle on poultry litter fertilized pastures tended to have higher weight gain in the summer (Figure 4). These seasonal differences in weight gain reflect the pattern of nutrient availability, weather conditions, and forage production. Fewer nutrients are released from poultry litter under cool conditions.

In a similar study, weight gain by stocker cattle on bermudagrass pastures fertilized with poultry litter was lower than on pastures with inorganic fertilizer. Again, the slow nutrient release of poultry litter and weather conditions were important factors in the animal’s performance. Nutrients released from poultry litter in late summer when conditions were hot and moist allowed better bermudagrass growth in the late summer (Figure 5).

Using Poultry Litter Wisely

Producers using poultry litter from their own houses are required to have nutrient management plans, which specify how much litter can be applied based on soil testing, forage needs, and the nutrient content of the litter. More information about nutrient management planning can be found on the AWARE website. Producers who obtain litter from brokers or other farmers should also use nutrient management planning to efficiently utilize the nutrients and prevent potential environmental impacts. Ask the farmer or broker for the results of a nutrient analysis of the litter. Brokers are required to provide a litter test report. Then use soil test information to determine the amount of litter that can be applied in a specific situation. If site specific information is not available, general application rates for different forage crops have been developed based on the nitrogen need of the forage and the typical nitrogen content of litter (Table 2).

Table 2. Common poultry litter application rates for various forages to meet nitrogen fertilizer requirements.
Forage Management Target Nitrogen Recommended Rates 1 Comments
Hybrid Bermudagrass Pasture 150-250 lbs 3 to 5 tons/ac Split application with half applied in early spring and other half in mid-summer. Higher application rates will cause excess phosphorus accumulation in the soil.
Hay 200-400 lbs 3 to 6 tons/ac
Common Bermudagrass, Bahia grass or Dallis grass Pasture 75-175 lbs 1 to 3 tons/ac Depending on grazing pressure, application may be split between early spring and summer.
Fescue/Orchardgrass Pasture 50-100 lbs 1 to 3 tons/ac The higher rate may be split between early fall and early spring.
Hay 100 lbs 3 tons/ac
Fescue/Clover mix
(<20-25% clover)
Pasture 50 lbs 1 ton/ac
Small Grains winter grazing Pasture 100 lbs 1 to 2 tons/ac The higher rate should be split between fall and late winter.
1 Based on average nitrogen content of fresh broiler litter of 62 lbs/ton.

Special Considerations

Forage Establishment

Poultry litter can be an effective soil amendment when forage crops are being established. Organic material in the litter can improve soil conditions for seeding and early seedling establishment if applied at moderate rates. Slow release of nitrogen is also useful because seedlings do not require high levels of nitrogen following emergence or during early development. Moderately high soil test concentrations of phosphorus and potassium are useful when legumes will be added to forage stands in later years.

Legume Establishment

Poultry litter should be used sparingly when interseeding legumes such as clovers into existing grass stands. Nitrogen in the poultry litter can increase grass competition with small clover seedlings, which can lead to legume failure due to shading. If grass competition is carefully managed with flash grazing, low rates of poultry litter can be helpful, particularly where phosphorus levels are low.

Forage Nitrates

Applying poultry litter above the recommended rate can result in increased nitrate concentration in forages. Nitrate accumulation is not specific to poultry litter. It occurs when an excess of nitrogen is available and conditions such as drought, cloudy days, or cool weather retard forage growth. Producers should be aware of these conditions and use recommended rates.


Studies have shown properly stored poultry litter does not contain viable weed seeds. If poultry litter is stored outside uncovered, then weed seeds can be introduced from birds or other sources. Many times weed species germinate or grow rapidly when additional nutrients are applied to pastures. These weeds are noticeable in pastures after poultry litter applications. Good pasture management techniques such as using the proper stocking rate, leaving enough forage height to maintain a dense and healthy forage cover, and judicious application of herbicides will help control weeds.


Poultry litter is widely used on pastures and hayfields in Georgia. There are many benefits when it is used wisely. Producers should use nutrient management planning and recommended rates to ensure poultry litter is used in ways that maximize its benefits without harming the environment.

Further Information

AWARE website. Animal Waste Awareness in Research and Extension.

Bellows, Barbara. 2005. Arsenic in Poultry Litter: Organic Regulations. ATTRA.

Cunningham, D.L., C. W. Ritz, and W.C. Merka. 2004. Best Management Practices for Storing and Applying Poultry Litter. University of Georgia College of Agricultural and Environmental Sciences Cooperative Extension Bulletin 1230.

Jones, F.T. 2007. A broad view of arsenic. Poultry Science 86:(1):2-14.

Ritz, C.W., and W.C. Merka. 2004. Maximizing Poultry Manure Use through Nutrient Management Planning. University of Georgia College of Agricultural and Environmental Sciences Cooperative Extension Bulletin 1245.

This document was supported by the University of Georgia, College of Agricultural and Environmental Sciences, Cooperative Extension, and the Georgia Pollution Prevention Assistance Division.

1 Extension Specialist – Land Application, Biological and Agricultural Engineering Department, University of Georgia
2 Extension Specialist – Soil Fertility, Crop and Soil Sciences Department, University of Georgia
3 Ecologist, USDA Agricultural Research Service, Watkinsville, Ga.
4 Forage Specialist, Clemson University

Status and Revision History
Published on Jun 11, 2007
Published on Apr 09, 2010
Published with Full Review on Apr 01, 2013
Published with Full Review on Aug 02, 2017

Using Manure in the Home Garden

Animal manure is a valuable soil amendment for home gardens. It not only supplies primary nutrients (nitrogen, phosphorus and potassium) and micronutrients for plant growth, but also is a source of organic matter. Increasing soil organic matter improves soil structure, increases the water holding capacity of sandy soils, improves drainage in clay soils, provides a source of slow release nutrients, and promotes growth of beneficial soil organisms. These manures used as fertilizers are typically from herbivores (i.e. plant-eating animals), such as cows, sheep, chickens, etc. (Never use cat, dog or pig manure in vegetable gardens or compost piles.)

The amount of nitrogen in and manure depends on many factors, including the type of animal it came from.

The nitrogen in manure is not available all at once to growing plants as much of it may be tied up in organic forms. Organic nitrogen becomes available to plants only after soil microorganisms decompose the organic compounds, converting the released N to NH4, which occurs over a period of years. The actual amount of this conversion varies considerably depending on the animal it came from, any bedding materials with it, temperature, moisture content, and handling. In general, about 30% to 50% of the organic nitrogen becomes available the first year, and the amount gradually decreases thereafter.
Fresh manure

Fresh poultry manure is is particularly high in ammonia.

Fresh manure typically has high amounts of ammonium or soluble nitrogen. This results in a higher available nitrogen content compared to composted manure. Poultry manure is particularly high in ammonia and readily burns if over-applied. Because of the high amounts of ammonia-nitrogen in fresh manure, it should be incorporated 6 to 8 inches within 12 hours after application. Without incorporation much of the soluble nitrogen will be lost to the atmosphere as ammonia. If the manure is mixed in with bedding or litter this will dilute the nutrient content. If there are large amounts of straw or sawdust, nitrogen availability to plants may be lowered by increasing the C/N ratio. High carbon relative to nitrogen (greater than 25 /1) will tie up nitrogen.

Fresh horse manure often contains lots of weed seeds.

Salts in fresh manure also tend to be high — especially in chicken, turkey, or other poultry manure. To avoid salt damage, wait 3 to 4 weeks after application before planting anything in the area.
Fresh manure may contain high amounts of viable weed seeds, which can lead to a weed problem. Horse manure is notorious for this, since those animals don’t digest what they eat as well as many other animals do, and seeds pass intact through a horse’s digestive system.

Do NOT use fresh manure on vegetables, particularly root crops.

Because of the potential of transmitting human pathogens, such as E. coli, fresh manure should never be used on fruits and vegetables. If you are growing crops where the edible portion is in contact with the soil (such as carrots, beets, or potatoes) fresh manure applications should be made at least four months prior to harvest. On other edible crops, fresh manure applications should be made at least three months prior to harvest. With just a four month or so growing season, this means you should only apply fresh manure in the fall; not in the spring or during the growing season to any area that is or will be planted with food crops.
Composted manure
Composting manure eliminates some of the problems of fresh manure — including the odor. It is lighter and easier to haul since it has less moisture, and the composting process may kill weed seeds and pathogens if the pile heats above 145°F. But salts may be more concentrated and some of the nitrogen is lost, leaving the more stable organic forms. Composted manure has lower availability of nitrogen and will contribute more to the organic matter content of the soil compared to fresh manure.

Many brands of composed cow manure are available commercially.

However, unless applied at high rates, composted manure alone may not be able to supply all the nutrients for fast growing plants. It’s not as important to immediately incorporate composted manure into the soil as for fresh manure, but incorporating it in to a depth of 6 to 8 inches is recommended whenever possible to obtain the full benefit from the compost. If spread in the spring, it is best to wait a least one month before planting crops so the microbial activity it stimulates won’t interfere with seed germination.
If you have convenient access to a supply of fresh manure you can try composting it yourself, but most people just purchase bagged composted manure that is readily available in garden stores and nurseries.
Nutrient availability

Many animal manures are mixed with bedding such as wood shavings in this chicken coop.

So how much manure should you use? If you purchased bagged composted manure, the label on the package will tell you the nutrient content and application rates. If you’re dealing with buckets of fresh or aged manure from a friend’s farm, the contents of your backyard chicken coop, or a donation from a neighbor’s horse barn it may be much harder to estimate whether what you’re spreading in the garden is too much or too little or just right.

Farm animal manure varies in its nutrient content.

The nutrient content of farm manure varies considerably depending on many factors. The availability of the nutrients from the manure for plant growth will depend on the breakdown and release from of the organic components. Generally, 70 to 80% of the phosphorus and 80 to 90% of the potassium will be available from manure the first year after application. Calculating nitrogen availability is more complex as it is dependent on microbial activity to make it available for uptake.
Suggested rates of fresh manure or compost to apply to supply about 0.2 lb of available nitrogen per 100 square feet:

Manure type pounds to apply
per 100 square feet
Dairy cow no bedding 75
with bedding 95
composted 200
Sheep no bedding 40
with bedding 50
Poultry no litter 20
with bedding 30
composted 70
Horse with bedding 65

A 5 gallon bucket holds about 25 lbs of fresh manure or compost, so you can estimate how much to use without actually weighing the materials. For example, use three buckets full of dairy manure without bedding spread over a 10 by 10 foot garden to add 0.2 pounds of available nitrogen. You’d need to add 8 buckets of composted cow manure over the same size area to apply the same amount of nitrogen.

A pot of black gold at the end of the rainbow.

In most cases, manure application is based on its nitrogen content and estimated availability for the first growing season. But remember that some manure contains high levels of phosphorus, so you may end up adding way too much phosphorus as you are incorporating enough manure to meet the plant’s nitrogen demands. It is important to have your soil tested to help determine if the level of phosphorus in the soil is building up too much (in which case you probably should use a different type of fertilizer that has low or no phosphorus for a while), as well as to know if other plant nutrient needs are being met with manure alone.

Proper use of manure in the garden can supply your plants with nutrients and help improve soil structure. Adding too much manure can lead to nitrate leaching, nutrient runoff, excessive vegetative growth and, for some manures, salt damage. And using fresh manure where food crops are grown poses risks for contamination with disease-causing pathogens.

– Susan Mahr, University of Wisconsin – Madison

Additional information: Safely Using Manure in the Garden – University of Wisconsin Garden Facts XHT1143

Best Manure For Gardens – What Are Different Types Of Manure

Adding nutrients to the landscape is an important part of land stewardship. Manure is one soil amendment that can help return those nutrients and juice up the soil, making it an effective growing medium for the next season’s crops. There are pros and cons of using manure as an amendment. The different types of animal manure have different levels of macro-nutrients and, therefore, must be adequately composted for effective use and used at different rates to prevent damaging plants with too much of one nutrient or another.

Is Manure Good or Bad?

What are different types of manure? Domestic pets and livestock can all contribute to manure for the garden, but each has a specific manner in which it should be handled for the health of your garden (and you in some cases). Manure is simply the waste products of animals that have been composted to remove any pathogens and break it down for quicker uptake by plants. Uncomposted manures must be used with caution, as they take longer to break down and may contain weed seeds or diseases that can be passed into your landscape.

Using manure as a fertilizer has probably been around since the early days of cultivation. Manures are a rich source of nitrogen as well as other nutrients. Since manure is a waste product, it must be used carefully.

Raw manures may be used, but there is odor associated with unbroken down waste, as well as the flies that it attracts. Among the pros and cons of using manure that is raw is that it be too “hot,” which means its concentration of nutrients may be too high for plants and burn them. Raw manures can also make plants grow too fast, leaving them thin and leggy and inhibit germination.

If you do use raw manure, apply it late in the season so the waste has time to break down before the next season’s planting.

What are Different Types of Manure?

Manure comes from any animal, but it isn’t all created equal. In order to kill any seeds and break down effectively, it needs to reach a temperature of at least 140 degrees Fahrenheit (60 C.) for a sustained time. The times vary dependent upon the different types of animal manure. For instance, any cat feces or dog manure must compost for at least two years and cannot be applied directly to food crops.

Human manure, or humanure, should never be used in the landscape. Drugs, diseases, and many more potential problems are harbored in our waste and only professional composters possess the tools and knowledge to adequately and safely compost human waste.

Traditional domestic livestock manures also contain varying amounts of nutrients and should be used at different times and in different ways. The most common types of manure used in gardening are:

Since manures contain different levels of nutrients, they need to be carefully applied to those plants that need the higher nutrient available.

  • Ideally, the best manure for gardens is probably chicken, since it has a very high content of nitrogen, a need all plants have, but it must be composted well and aged to prevent burning plants. Chicken manure is a rich source of nutrients and is best applied in fall or spring after it has had a chance to compost.
  • Similarly, cow manure, which has a 0.5-0.2-0.4 ratio, is composted beforehand for better results.
  • Sheep manure has a high nitrogen content but lower ratio in the other macro-nutrients; however, its pellet size makes it a quick waste to compost.
  • Horse manure takes longer and has similar content to cow manure but its larger size and the weed seeds the animal digests means it takes much longer to age and compost.

The best manure for gardens really depends upon what you can get your hands on easily. Any of the common varieties can be beneficial to soil. Just remember to allow the manure to compost fully for at least 6 months or longer, or add it raw, and till it into the soil at least a season prior to planting.