Fertilizer Management
Poultry Litter Nutrient Management in Forage Production
Pasture and forage production is vital to most Mississippi cattle operations. "Chicken fertilizer" is well known by poultry farmers as a valuable fertilizer for pasture and forage production. Poultry litter is an excellent soil amendment that provides nutrients for growing crops, and also improves soil quality when applied wisely. It is estimated that 85 to 90 percent of poultry litter produced annually in Mississippi is applied to pastures and forages on the farm of origin.
Environmental concerns and shifting land use to forestry in the concentrated poultry region has focused attention on more widespread litter uses. In addition, the rapid increase in commercial nitrogen fertilizer prices due to higher natural gas prices has generated interest by non-poultry farmers in litter use and management in soil fertility programs.
All farmers who use fertilizer, whether poultry litter or commercial, should be aware of the principles of nutrient management. This simply means you know what is applied, where it's going, how much, and how you do it. Using nutrient management planning, and implementing the prepared plan is good business sense, and gives efficiency and credibility to the fertilizer program. The foundation of nutrient management using poultry litter is using testing to quantify your current soil fertility status and the plant nutrients in the litter (see accompanying sidebar).
Each farm should develop a sound, regular soil testing program regardless of any permit requirements. It is an inexpensive, easy to do Best Management Practice that also happens to be an extremely powerful management aid. The report will include pH, lime requirement, and nutrient levels in the soil represented by the sample.
One interesting effect of using litter in soil fertility management is that we have seen increasing pH levels and decreasing lime requirements over time in most soils. This is currently attributed to dicalcium phosphate in the poultry diet which leads to significant calcium levels in the litter. Thus when litter is land applied, it has a liming effect.
Increasing the pH by meeting recommended lime requirements will have the extra benefit of increasing availability of native nutrients in the soil. The recommendations accompanying the soil test results will offer suggestions for maximizing crop yields in an economic manner.
Poultry litter, and other animal by-products, are slow release nitrogen and phosphate fertilizers. However, research has shown that a large percentage of the total potash from litter seems to be more available soon after land application. Testing the nutrient content of the litter helps us manage the plant nutrients in the litter more efficiently. About half of the total nitrogen applied as litter is available to growing crops in the year of application. The phosphate used by plants in the application year varies widely, from twenty to eighty percent of total applied depending on soil types and other factors.
Litter applied in sufficient quantity to meet the nitrogen needs of a healthy growing crop results in more phosphate added to the soil than the plants can utilize. Until the early 1990's, it was thought soils had an infinite capacity to store this unused phosphate. However, creditable, quality research has shown that in certain situations, this storage capacity can be exceeded and the phosphate may move through or from the soil where it was applied.
Another very important laboratory analysis necessary for optimum litter management is moisture content. Recent Mississippi State research has found the water naturally in the litter varies from ten to forty percent of the total weight, so it is critical to know the moisture content if litter is being purchased. With the moisture content and nutrient percentages of the litter it is possible to calculate the actual pounds of nutrient in the litter (see example calculation).
Application management should be based on common-sense, attainable yield goals for the particular pasture or forage crop. Yields over the past few years of drought conditions may not be the best guide for setting goals. On long-term poultry/cattle farms there is concern about phosphate removal rates. Cutting hay will remove much more phosphate (as well as potash) than grazing cattle on the same acreage.
Litter weighs about 31 pounds per cubic foot, much lighter than inorganic fertilizers. Therefore, one problem is new users of litter as fertilizer do not have equipment with sufficiently large gates to effectively spread the material. Spreaders should feed evenly, and have a good pattern that covers the throw path well.
Application on wet soils should be avoided to minimize soil compaction and nutrient loss through runoff and other pathways. Care should be taken to absolutely avoid direct application to water along creeks and other water bodies. Incidentally, it is best to maintain good application offsets along property lines as most complaints to authorities about litter application in Mississippi have come from annoyed neighbors.
Much more information is available about utilizing poultry litter in Mississippi farming systems through the MSU Extension Service. Recent publications cover nutrient management, livestock feeding, research and Extension programming, environmental issues, soil and litter testing, and other aspects of using this valuable resource. Please contact your local office for this material.
SIDEBAR:
The Mississippi Phosphorus Index was developed by the Mississippi Natural Resources Conservation Service and the Mississippi State University Extension Service with input from many stakeholders to address conditions in the state. Phosphorus Index based risk analysis looks at factors such as soil test phosphorus levels, soil permeability, field slopes, litter application rates, and distance to surface water to determine the probability of nutrient movement in the landscape.
Farms with a history of poultry litter application, or that will be used as part of a poultry grower's site permit Waste Management Plan, should perform an environmental risk analysis using the Phosphorus Index. The process determines the potential of each field on a farm to contribute to nutrient movement to adjacent waters. In the planning process the results of various management options can be evaluated to find the best economic and environmentally protective plan for a specific field and farm.
County Natural Resource Conservation Service offices and certified third party vendors of conservation planning services utilize this tool in working with poultry growers. Contact your local MSU-Extension Service office for more information on how the Phosphorus Index may be used in your situation. The Extension office can also provide information on soil and litter testing.
Sample calculation using litter analysis results:
water content = 25% (therefore dry matter = 75%)
nitrogen content = 4%
phosphate content = 2%
potash content = 3%
Calculations:
2000 pounds litter per ton times 0.75 dry matter = 1500 pounds dry matter per ton
1500 pounds dry matter per ton times 0.04 nitrogen content = 60 pounds nitrogen per ton
1500 pounds dry matter per ton times 0.02 phosphate content = 30 pounds phosphate per ton
1500 pounds dry matter per ton times 0.03 potash content = 45 pounds potash per ton
Summary:
In this case, one ton of litter contains 500 pounds of water, 1500 pounds of dry matter, 60 pounds of nitrogen, 30 pounds of phosphate, and 45 pounds of potash. This are general results, individual growers should use data from their own situation.