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Manure tests are the best way to know the fertilizer value of any type of manure. But understanding a manure test report can be a challenge. Fortunately many manure testing labs have been updating their manure test reports to make them easier to understand an easier to use.

To use manure you need to know the nitrogen, phosphorus and potassium fertilizer value of the manure. The example below (Figure 1) is based on a manure test from a Missouri Lab and provides all the information you need to make a fertilizer recommendation with this manure source.

These results are reported on an "as-is" basis which is what farmers are expecting. The results also have been converted to units the farmer is expecting. In this case, with turkey litter, the farmer is expecting a result in "lbs/ton".

There are many forms of nitrogen in manure and not all nitrogen in manure is available to the crop. Some test results, including this one, report "P.A.N." (plant available nitrogen) or "available nitrogen". Use these estimates of availability with caution. In this case the report clearly states the estimate of P.A.N. is for surface applied manure and reports the availability factors used to determine P.A.N. at the bottom of the report. This estimate of available nitrogen is appropriate for surface applied litter in Missouri.

All manure phosphorus and potassium are equivalent to the same amount of commercial fertilizers. Be sure to use the estimates based on phosphate and potash to develop fertilizer recommendations.

Not all manure tests report the fertilizer value of manure in such useful units. Many times you will need to convert values from less useful units into something the farmer knows how to use. Find more information on interpreting manure test reports and converting report values into useful units in the MU Guide EQ215 Laboratory Analysis of Manure.

For more information on labs that do manure testing see my website ( http://nmplanner.missouri.edu/manure_labs_state.asp ).

John A. Lory
Division of Plant Sciences and
Commercial Agriculture Program