Not all manure is created equal

Every livestock species has different manure characteristics that influence its value.

by Leslie Johnson

Chickens, hogs, beef cattle, and dairy cows all produce manure. These various kinds of manures are valuable, but are they equally valuable? The answer to that question is absolutely not. Ranking priority might be based on the potential for offensive odor, nutrient content, proximity to target fields, or the ability to influence soil health characteristics. This article will compare different manures and explain why not all manures are created equal.

Nutrient differences

Using a few random samples, let’s compare the nutrient concentrations across species. Note that these are not averages; they are just one sample each from various sources in Nebraska.

Using these analyses and Nebraska’s nitrogen availability factors, the following manure application rates are based on a field target nitrogen (N) application rate of 154 pounds per acre available for the 2023 crop (if applied in fall 2022):

• 4,000 gallons per acre of swine manure (injected)

• 37 tons per acre of beef manure (surface applied, no incorporation)

• 13,000 gallons of dairy lagoon slurry (injected)

• 9 tons per acre of layer manure (surface applied, no incorporation)

That means it would take four times as much beef manure to provide the same amount of nitrogen as layer manure. Four times! Yet, beef manure would provide significantly more organic matter than layer manure. So, depending on your goals, either source could be a good option for your specific cropping situation.

A visual representation of available nutrients (letters), water (droplet), and organic matter (yellow stone) content for various types of manure applied at a rate of 154 pounds of nitrogen per acre. The upper left quadrant represents layer chicken manure that has been broadcast applied and left on the surface. The upper right represents swine pit slurry that has been injected into the soil. The lower left represents beef feedlot manure that has be surface-applied, and the lower right represents dairy lagoon manure that has been injected.

What about the other nutrients in manure? The table shows estimates of available nutrients when each manure is applied at the target of 154 pounds of N per acre rate indicated above.

Using data from the table, we see that beef manure applied to meet 154 pounds of N per acre would supply nearly three

Pounds of nutrient availability the first year from various manures, applied at 154 lbs. of N per acre

times as much phosphorus and almost five times the amount of potash as swine manure. So, when applying manure to a field that has adequate soil phosphorus and low potassium concentrations for the next crop, more value might be assigned to swine manure if manure transportation costs are economically viable. However, if the field is needing phosphorus, beef manure might be just the ticket to build soil phosphorus while improving soil properties through additional organic matter inherently associated with cattle manure, offsetting commercial fertilizer costs for a number of years.

Manure application logistics

While balancing nutrients is important, a farmer considering manure use also must think about the availability and characteristics of the product. Swine and dairy manures are usually more costly to transport due to their high water content, whereas some poultry litters can be transported long distances based on higher nutrient concentrations and lower water content. Liquid manures are just too heavy, and therefore costly, to haul long distances, so transportation costs are an important economic factor.

Building soil health

There is not a lot of research on how different types of manure impact soil health, but research has proven that manure in general is superior to commercial fertilizer for building soil organic matter concentration, reducing soil bulk density, and improving aggregate stability and infiltration rates. Solid manures, like beef manure and poultry litter, typically contain larger concentrations of organic matter, which benefits soil health, compared to more dilute slurry and liquid forms of manure. If left on the soil surface, manures with organic matter may create a mulch-like effect, conserving soil moisture and decreasing erosion and runoff. And, the soil health hallmark benefit from manure application is that soils are more resistant to compaction — especially when they’re wet.

When balancing nutrients needed on your fields, compare manure sources and remember that not all manure is created equal. When deciding on a manure source, consider not only the availability and cost, but also the nutrient content, characteristics of the product, and how those characteristics affect the field in the long run. 

The author is an animal manure management extension educator with University of Nebraska Extension. She would like to recognize Alfredo DiCostanzo and Todd Whitney, University of Nebraska Extension educators, for their time reviewing this article.

Nitrogen Availability In Nebraska

In Nebraska, research has shown that for most manures, organic nitrogen is about 40% available the first growing season, with about 20%, 10%, and 5% becoming available in subsequent growing seasons. Ammonium nitrogen is assumed to be 95% available when injected versus completely lost to the atmosphere if surface applied without incorporation.

https://doi.org/10.1016/j.fcr.2019.107577