By Glen Arnold, CCA, Ohio State University Extension
Due to the increase in fertilizer prices, there is renewed interest in the nutrient value of manure, including bedded-pack manures that involve straw, sawdust, or wood chips to absorb moisture. The nutrients and organic matter in pen-pack manure are an excellent addition to farm fields.
The most common types of bedded manure are beef, dairy, and sheep or goats. Small ruminant bedded pack manure contains the most nutrients per ton followed by beef manure and dairy manure.
Pen-pack manure contains the macro nutrients nitrogen, phosphorus, and potash along with a host of micronutrients. The nutrient content can vary depending on species, feed products fed, and the amounts of straw or sawdust used for bedding. The farm’s manure handling and storage practices also impact the nutrient content of manure. Manure stored under roof will usually maintain a higher nutrient value than manure exposed to rainfall.
Pen-pack manure nutrients are measured as pounds of nutrient per ton of manure. Typically, the nitrogen content will be 10 to 16 pounds per ton. About two pounds of this nitrogen is in the ammonium form and the remainder will be in the organic form. While ammonium nitrogen is immediately available to a growing crop, organic nitrogen takes time in a field to mineralize and become available over three or four years. The phosphorus content, in the P2O5 form, will usually be from 6 to 12 pounds per ton. The potash content, in the K20 form, will usually be between 10 and 15 pounds per ton.
Applying pen-pack manure can be more precise if you know the application rate being applied in tons per acre. If you are unsure how many tons per acre your solid manure spreader applies there is a simple way to make a determination. Make a tarp that is 56 inches by 56 inches (21.8 square feet). Fasten it to the ground with weights on the corners and apply manure across the tarp. Fold up the tarp and weigh the manure captured. Many people use a bathroom scales for this. One pound of manure captured on the tarp is equivalent to one ton of manure applied per acre. Thus, if you captured 10 pounds of manure the application rate was 10 tons per acre.
We always want to keep water quality in mind when handing manure. The goal is to make good use of the manure nutrients and keep the manure nutrients out of streams and ditches.
For more information about how and when to sample manure, Penn State Extension has a good publication available on-line at http://extension.psu.edu/plants/nutrient-management/educational/manure-storage-and-handling/manure-sampling-for-nutrient-management-planning.