Poultry litter management spreadsheet instructions.
The spreadsheet can be downloaded for free at www.agecon.okstate.edu/faculty/publications.asp
This spreadsheet was developed to help producers place a value on poultry litter in comparison to commercial fertilizers. Prior to using the spreadsheet, producers are encouraged to have their pasture or field soil tested. The spreadsheet requires nutrient recommendations from a soil testing laboratory. Contact your county Oklahoma Cooperative Extension Service (OCES)office or OSU Soil, Water and Forage Analytical Laboratory (http://www.soiltesting.okstate.edu/) if you have questions regarding soil testing.
The spreadsheet has four pages, “Inputs,” “$ per ton,” “$ per acre,” and “Additional nutrients needed.” Click on the tabs on the bottom left of the MS Excel spreadsheet to navigate between the pages.
User supplied information
In order to value litter, users are required to enter information regarding nutrient requirements, pH, nutrient composition and availability of litter and cost information. This information is divided into five areas on the Inputs tab.
First, the Inputs page requires that the user enter nutrient recommendations from soil test results and soil pH level as in Table 1. More information on soil test results and interpretation can be found in the pdf at: http://factsheets.okstate.edu/documents/pss-2225-osu-soil-test-interpretations/
Table 1. Nutrient Recommendations and Soil pH (lbs/acre).
Second, users are required to enter prices for commercial fertilizers including urea (46-0-0), DAP (18-46-0) and potash (0-0-60). These should be the price paid to the fertilizer dealer plus delivery and application cost on a per ton basis (see Table 2). The spreadsheet will impute the price per pound of actual N, P2O5 and K2O based on these prices entered by the user. Note, OSU does not maintain a list of commercial fertilizer prices. Users will need to contact a local fertilizer dealer to get nearby prices.
Table 2. Fertilizer Prices.
Third, users enter the pounds of N, P2O5 and K2O contained in one ton of litter (see Table 3). Sellers of litter may be able to provide this information or purchasers can have samples analyzed. Again, your county OCES office or OSU Soil, Water and Forage Analytical Laboratory can assist with obtaining a litter nutrient analysis.
Table 3. Litter Nutrient Composition (lbs/ton).
Fourth, users provide an estimate of nitrogen availability over time from litter as in Table 4. As nitrogen is tied up in organic form, not all nitrogen from litter is available during the first growing season. Nitrogen is gradually converted in the soil from its organic form to forms available to plants. Additionally, some nitrogen will be lost due to volatilization or run-off. As a result, only a fraction of nitrogen applied as poultry litter (or other animal waste) will be available to plants in the first growing season. Note, that incorporating litter into the soil will decrease the amount nitrogen lost to volatilization or run-off. More information on nutrients in animal waste can be found at the OSU Manure and Animal Waste Management website: http://www.animalwaste.okstate.edu/. An estimate of the liming value of litter is also required if soil pH is less the 6. A default value of $2 per ton is based on the opinion of several OSU waste management and soil fertility researchers.
Table 4. Nitrogen Availability.
The fifth set of inputs (Table 5) address costs, interest rate and frequency of application. Costs include the Purchase, Loading, Application, and transportation costs. Purchase, loading and application costs are per ton values. Transportation costs are computed using Hauling Cost per loaded mile multiplied by the Hauling Distance (miles) and divided by the loaded weight (Tons per load). Enter Operating Note Interest Rate as a percent. This value will be used to discount the value of nutrients supplied by a current application of litter to future growing seasons. Years between applications is used to determine the amount of P2O5 and K2O available after the first growing season.
Table 5. Costs.
|Hauling Cost per loaded mile||$/mile||4.00|
|Tons per load||tons||25.00|
|Operating Note Interest Rate||7.00%|
|Years between applications||2|
The spreadsheet reports results on three separate pages, $ per ton, $ per acre, and Additional nutrients needed. The spreadsheet computes the amount of litter needed to meet 1) N requirements, 2) P2O5 requirements and 3) P2O5 requirements. When balancing on either P2O5 or K2O, up to three years of P2O5 or K2O will be applied based on the value entered by users on the Inputs tab. Years between application is used to determine how many year’s requirement of P2O5 or K2O will be applied. For example, entering a “3” in the Years between application generates an application rate that will supply three year’s requirements of P2O5 (if balancing on P2O5)or K2O (if balancing on K2O).
The first set of results are reported in $ per ton (as in Table 6). The table reports tons of litter to apply per acre if balancing on N, P2O5 or K2O. However, the recommended application rate is constrained to comply with Oklahoma regulations on P2O5. The spreadsheet will not recommend an P2O5 equivalent in excess of 200 pounds per acre surface applied or 400 pounds per acre incorporated.
Table 6. Per Acre and Per Ton Value of Poultry Litter.
The values of N, P2O5 and K2O are reported for surface applied and incorporated litter. The values vary depending on the nutrient that is used for balancing. Liming value is included if pH is less than 6 and the user provided a nonzero value on the Inputs page. Gross value sums the values for each of the three nutrients and liming value. Costs are the sum of Purchase, Loading, Application, and transportation costs. Net values are the values of litter per ton in comparison to commercial fertilizer. In other words, Net Value is the cost advantage (or disadvantage) over (under) commercial fertilizer given the values that the user entered.
The values of N, P2O5 and K2O available after the first growing season are discounted to present value using the Operating Note interest rate as the discount rate.
The next page or tab, $ per acre, multiplies the values from the $ per ton page by the number of tons applied per acre. Thus, all values in $ per acre (see Table 6).
The final page or tab, Additional nutrients required (Table 7), computes YEAR 1 nutrient requirements above the amounts supplied by litter. These additional nutrients will need to be provided using commercial fertilizer or other sources. Note even if the user balances on nitrogen, additional N may be necessary. Recall litter is limited to providing less than 200 pounds P2O5 surface applied and 400 pounds P2O5 incorporated. Even when balancing on P2O5, additional phosphorous may be required as applied nitrogen from litter is also limited to plant uptake as indicated by recommended N.
Table 7. Additional Nutrients Required.
|Additional Nutrient Requirements Balancing on N (lbs per acre)||Additional Nutrient Requirements Balancing on P (lbs per acre)||Additional Nutrient Requirements Balancing on K (lbs per acre)|
|Surface Applied||Incorporated||Surface Applied||Incorporated||Surface Applied||Incorporated|
Use of litter may not meet all nutrient requirements. Additional nutrients may be needed depending on recommendations, nutrient content of litter and whether balancing on N, P or K.
Eric A. DeVuyst
Associate Professor, Farm and Ranch Management Specialist
Department of Agricultural Economics
Area Agricultural Economics Specialist
Cooperative Extension Service