As fertilizer prices rise, the manure option looks better
The ever-increasing cost of natural gas (and commercial fertilizer) is making manure look more attractive to farmers every day.
Extension specialists across the Midwest are encouraging crop producers to consider manure as a viable alternative to commercial fertilizer, says Ted Funk, University of Illinois Extension agricultural engineer.
Although the use of manure is not without its challenges, Funk says, manure is a valuable resource and needs to be treated as such during land application.
"Producers, especially those who are only familiar with commercial fertilizer, can gain considerable nutrient value from manure by looking at some basic management options," says Funk. "Fortunately, the same management options that retain and recycle manure nutrients are also the same practices that protect the environment."
Some of the questions farmers need to consider include:
- What are your crop needs? Soil tests determine the amount of phosphorus (P) and potassium (K) in your fields.
"If you've got some poor ground, where your soil phosphorus and potassium tests are low, that's where you should put manure first," Funk says. "If a field is already rich in P and K, making repeated applications of manure at a nitrogen rate to ensure high-yield corn crops can create environmental problems down the road due to excessive phosphorus and potassium."
- What manure is available within a three- to five-mile radius? Hauling manure is part of the cost of application, and transporting manure up to three to five miles is generally doable. As a rule, the cost of manure application should be kept below a penny or a penny-and-a-half per gallon. Many commercial applicators have purchased equipment that allows them to increase the distance they can efficiently haul manure. The farther you haul manure, the more you want to be hauling the most nutrient rich manure to the most needing fields.
- What is the form of the manure? Solid manure must be spread on top of the ground, and is sometimes incorporated, or disked in, afterwards. This can mean there is a noticeable odor when spread and a significant loss of nitrogen through volatilization until the manure is incorporated, says Funk. Incorporation not only decreases the odor, but also helps retain the nitrogen and reduce the risk of runoff.
"And if you're on highly erodable land or in an impaired watershed, surface application is not a good economical or environmental choice," Funk says.
Liquid manure can be applied using sprinkler irrigation or injection. Sprinkler irrigation of liquid manure should only be done on fields remote from public roads or residences because of the intense odors released. In addition, the loss of increasingly valuable nitrogen can be appreciable. Injection allows you to place the nutrients below the surface, in the root zone, where odors, runoff and evaporation are much less of a problem. However, said Funk, application by injection normally costs about four times as much as sprinkler irrigation, so again, be sure you are placing the nutrients where the crops will most utilize them.