Taking accurate manure samples
Manure analysis can give accurate guidelines for making decisions on which fields to apply manure and the optimum rate, but the analysis is only as good as the sample taken.
High fertilizer prices make livestock farmers more aware ofthe value of their manure. Manureanalysis can give accurate guidelines for making decisions on which fields toapply manure and the optimum rate, but the analysis is only as good as thesample taken. Taking good samples isespecially hard in liquid storage ponds/lagoons that cannot be completely agitated, if at all.
Below is a picture showing how a liquid storage structure may stratify over time. If you have a large liquid storage, think about spending the money to take at least 3 representative samples as you empty. Each layer will have a differing manure analysis that will affect the application rate and dollar savings on fertilizer. Since these layers vary so widely, and the manure has such a high value, it just makes good economic sense to take multiple samples.
Solids tend to settle out over time to the bottom of the manure storage; with these solids is the majority of the phosphorus nutrients. According to “Fertilizer Nutrients in Livestock and Poultry Manure” by Charles D. Fulhage and Donald L. Pfost, Agricultural Engineering, University of Missouri Extension, up to 80% of the phosphorus can remain at the bottom of a liquid storage structure if not completely agitated.
A good guideline is that when you are hauling solids from the bottom of a storage structure,utilize that manure on your lowest phosphorus testing fields, even if that means driving some distance. Depending on the analysis, you may also have to apply that bottom material much thinner than compared to the manure in the upper portion of the storage. To be in conformance with the Manure Generally Accepted Agricultural Practices, manure cannot be applied to soils that test above 300 lb/acre Bray P1 (or 150 ppm) so it’s important to apply this high phosphorus content manure to the most appropriate (lowest testing) fields.