Warren A. Dick
Agriculture and Natural Resources
School of Natural Resources
Jay W. Johnson
School of Natural Resources
Donald J. Eckert
School of Natural Resources
Poultry litter is a mixture of manure and bedding material and Ohio's poultry industry produces large amounts annually. Considering this significant output, litter management has become an important issue for both the poultry industry and Ohio farmers as they search for more economical and environmentally sound ways of utilizing litter as a farming resource. Compared to mineral salts, organic amendments offer several advantages (Table 1). Rising interest in using poultry litter as a soil fertilizer for crop production is due to the fact that it contains significant amounts of nutrients essential for plant growth. These nutrients are the same ones as those encountered in commercial fertilizers commonly used by farmers today. The most important are the macronutrients, nitrogen, phosphorus, and potassium. In addition, poultry litter contains other essential nutrients in lesser or trace amounts.
|Table 1: Comparisons of organic amendments and mineral salts as fertilizers.|
Experience has shown the nutrients in poultry litter become available for plant uptake when applied to soil. Unfortunately this availability of nutrients in litters, as compared to the same nutrients in commercial fertilizers, is unpredictable. Phosphorus and potassium become most readily available in soil, while nitrogen has the slowest release rate of the three major nutrients. In order to create a balance of nutrients in their soils, farmers must plan a method of fertilization according to these differing release properties. Two possible strategies are: (1). apply litter so as to receive the desired amounts of phosphorus and then add commercial potassium and nitrogen fertilizers to make up the difference in these nutrients or (2). apply enough litter so as to insure a proper amount of nitrogen will be released into the soil. This second method increases the risk of oversupplying phosphorus and potassium, thereby adversely affecting soil and water quality.
Chemical composition of poultry litters and soil factors can both influence the amount of nutrients released and the rate at which they are released. In general, net nitrogen mineral release seems to be more rapid from fresh poultry litter applied on coarse textured soils than from aged (or composted) litter applied on fine textured soils.
The best method to determine the appropriate rate of application of poultry litter is to have it tested at a reputable laboratory. Based on the nutrient and moisture content of the litter sample, the amount of nutrient per unit volume of litter can then be calculated.
Nutrient content in litter (Table 2) depends on the type of bedding used, feed source, etc. Calcium supplement for egg layers increases the calcium carbonate concentration in the litter. It also results in an increased pH in the litter which, in turn, increases the potential for nitrogen to be lost as ammonia gas.
A field priority system can be developed to maximize the nutrient value of the litter based on the fields which require the greatest amount of nitrogen to grow the crop, have the lowest phosphorus and potassium soil tests, and will benefit from adding organic material to the soil.
The time of application can be extremely important. Fall application allows maximum time for litter to decompose and release nutrients for the next year's crop. However, this also provides the greatest potential for soluble nutrients to be lost by leaching and for nitrogen to be lost by denitrification. Spring application will usually conserve more of the nutrients but may also interfere with other types of farm operations that must be accomplished in a timely manner. If possible, the litter should be tilled into the soil immediately after application to avoid gaseous losses of nitrogen and runoff losses of other nutrients. This is especially important for egg layer litter which has high calcium carbonate content and high pH. For no-tillage crop production, it may be possible to try to time applications to coincide as much as possible to occur prior to a rainstorm event or use subsurface placement to apply the litter. Buffer strips may need to be used to protect surface waters when litter is applied and not tilled into the soil.
Nitrogen in poultry litter is primarily available the first year after it is applied. Most of the ammonium nitrogen, and approximately 1/3 to 1/2 of the organic nitrogen, is available the first year after application. Just as when mineral nitrogen fertilizer is applied, not all nitrogen that is available will be taken up by the crop. Some may be lost by leaching and denitrification, some will be incorporated into soil organic matter, and some will remain fixed in the soil. The amount of nitrogen available the second year after litter application is difficult to predict because it is highly depended on climatic conditions during the previous year and the crop grown. However, one should generally count on only 5% or so of the total nitrogen applied to carry over from one year to the next. The nitrogen carry over will actually vary depending on the number of years litter is applied. A soil treated only once will carry over almost no nitrogen whereas a soil treated annually for five or more years may carry over more than 10% of the applied nitrogen.
The litter utilization and cropping systems used on a particular field should maintain Bray P1 soil-test phosphorus levels not greater than 60 pounds per acre in the top eight inches of soil (equivalent to a 30 ppm soil test value). Special precautions need to be taken if soil tests exceed this level. These would include avoiding litter application rates that would add more phosphorus to soil than is removed by the crop and to practice proper soil and water conservation. If the Bray P1 level exceeds 300 pounds per acre (150 ppm soil test value), no poultry litter application to the soil is recommended.
|Table 2. pH, organic carbon content, and nutrient composition of poultry litter.|
|Parameter||Egg layer litter||Broiler litter|
|Organic C (%)||15.3(4.7)+||32.5|
|+Value in parenthesis is inorganic C as calcium carbonate.|
This publication was produced through a cooperative effort between Ohio State University Extension Service and the College of Food, Agriculture and Environmental Science.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
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