Throughout history, farmers who raise dairy, beef, hogs, sheep, poultry or other livestock have used manure as a fertilizer. Manure contains many useful, recyclable components, including nutrients, organic matter, solids, energy and fiber.

With today’s technology, manure can be used more efficiently, which lessens many of the environmental concerns that result when manure is treated as waste. Farmers use manure as a fertilizer to provide nutrients needed for crop production.

“Manure nutrients have real value as fertilizer,” says Jerry Clark, Extension crops and soils agent for Chippewa County, Wis. “The fertilizer value of manure increases as the price of commercial fertilizers increases. Even though fertilizer prices are down a little this year, they are still high.”

Recycling nutrients

Like commercial fertilizer, manure must be managed properly to avoid environmental impacts.

“Using fresh manure as a fertilizer to raise crops that will be fed back to the livestock is an excellent way to recycle nutrients,” Clark explains. “Ideally, fresh manure would be used on the farm where the manure is generated or on a neighboring farm, because fresh manure is expensive to haul even short distances.”

Manure is commonly land-applied as a semi-solid or liquid.

“Farmers can incorporate manure into the soil or inject it under the soil surface to reduce the risk of runoff losses and odor problems,” Clark says. “The value comes from incorporating the manure into the soil. If fresh manure is incorporated within 72 hours, you have more nutrients. It all boils down to what is available to the plant, and a lot of that is determined by how quickly it is incorporated into the soil.”

The most expensive nutrient (per unit) that crops need is phosphorus, Clark says. “For dairy, livestock and poultry farmers, the good news is that manure from most farm operations can meet the phosphorous need of the crop.”

While excess phosphorus presents a nutrient management challenge, some of the reasons phosphorus in manure oversupplies what is necessary for crops can be easily remedied.

“The practicality of manure is the transportation of it,” Clark says. “Commercial fertilizer is designed to be hauled distances more easily than manure.”

According to Clark, custom manure applicators are injecting manure in the soil with increasing precision.

“How much manure and where it goes has gotten more precise,” he says. “Applicators do an excellent job of getting the rates to meet the nutrient management plan. That injection or incorporation is what increases the value of manure as a fertilizer. If it can be worked into the soil, that is a much more efficient use of the manure.

“If you daily haul, some of that manure nutrients will be lost due to surface loss if it is not incorporated,” Clark adds. “Most manure is applied in the fall and the spring, because it is more convenient, and farmers are capturing a lot more of the value of manure by incorporating it. Storage does have the environmental benefit that you are not putting that manure out there during the high snowmelt months.”

Nutrient management plans

Most nutrient management plans are phosphorus-based, Clark explains.

“If you are trying to get the biggest bang for your buck, consider applying manure at a lower, phosphorus-based rate, and then supplement the rest of the nitrogen needs for the crop with commercial fertilizer,” he says. “That way, the nutrients are balanced for crop needs, and you can spread manure on more fields.”

According to Clark, manure produced from any dairy, other livestock or poultry operation has tremendous fertilizer value. And it doesn’t matter if it is stored in a pit or a lagoon or is hauled fresh daily.

“The value comes from incorporating the manure into the soil,” he says. “If fresh manure is incorporated right away, you have more nutrients if it is incorporated within 72 hours. It all boils down to what is available to the plant, and a lot of that is determined by how quickly it is incorporated into the soil.”

Numbers game

But in actual monetary values, what is manure worth? According to Leslie Johnson, Nebraska Extension animal manure management educator, the answer depends on understanding an important difference between gross value and net value of the manure.

In a recent news release, Johnson said that gross value is simply the equivalent commercial fertilizer value of the nutrients contained in the manure. The net value, on the other hand, is more difficult to figure because it includes the effects of application method, transportation and cropping system nutrient needs — along with the intrinsic values that are much more challenging to quantify, as Clark mentioned.

The value depends on the following aspects:

A little math

To figure out the actual monetary value of manure, we need some information first. Follow these four steps:

Step 1. We need to know the cost of fertilizer, obtained from the local supplier, to know the value of the nutrients in any fertilizer product, Johnson said. Using urea as an example, it has a percentage of primary nutrient as 46% nitrogen, for instance. If urea costs $775 per ton, the math is simple: $775 divided by 2,000 pounds (weight of a ton) divided by 0.46 (percent of nitrogen in urea). That would equal 84 cents per pound of nitrogen.

Step 2. How much of the manure nitrogen is available to the crop? A lot of factors play into the answer, including temperature at the time of application, if the product is incorporated, and the type of animal and housing the manure came from, Johnson said. University of Nebraska research says that most species of livestock, dairy or poultry have about 40% of the organic nitrogen available the first year, with an additional 35% becoming available over the following three years.

If we use beef manure as an example, with about 13 pounds of organic nitrogen, it calculates to about 5 pounds per ton the first year and another 4.5 pounds in the next three years. This comes from the following equation: 13 pounds of organic N in manure multiplied by 0.40 (40%) available, equaling 5 pounds of N in the first year. The same equation is used to calculate the 4.5 pounds available nitrogen in the future years. Adding 5 pounds for the first year and 4.5 pounds available in the future equates to a total of 9.5 pounds of N value in a ton of the manure.

Step 3. What is available to the crop? Johnson noted that most beef manure in Nebraska is not incorporated, so ammonium nitrogen is completely lost and is not available due to volatilization. If the manure is sidedressed through injection, up to 0.95 is available the first year; or through the center pivot, where 0.80 is available the first year. For this example, however, no ammonium nitrogen is available.

Step 4. Using the 84-cents-per-pound of N and multiplying that by the total N value of 9.5 pounds per ton, we get a total value of $8 per ton in N. However, Johnson reminded producers that manure contains a lot more nutrient value than just N, so the process needs to be repeated for all nutrients, adding the total value together.

Using the example of beef manure, Johnson said that 1 ton in their calculations was worth about $30.25, accounting for N, phosphorus, potassium, sulfur and zinc. But she reminded producers that typically more than 1 ton of manure is applied at one time, making that manure a valuable part of a livestock and cropping operation — not only for the current cropping year, but also for years to come.

This UNL worksheet can help with the math in figuring the value of manure.