sealPurdue News

May 1996

Computer helps spread manure

WEST LAFAYETTE, Ind. -- Anyone who has compared a computer program to a pile of, er, manure might want to think again. There's money in that pile, and Purdue University has developed a computer program to help farmers cash in on it.

The program is called AMANURE, and it helps farmers use manure as a more efficient fertilizer. "It determines storage volumes, application rates, acres needed for application and if supplemental fertilizer is needed for specific crops," says Don Jones, Purdue agricultural engineer.

For centuries some farmers have used manure as a fertilizer, but many others treated it as a liability, a waste product to be disposed of.

Gary Eller, who set up a custom sludge applicator's business on his family's farm near Kokomo, says, "Even those who used manure as a fertilizer had to guess at its nutrient value by hit-and-miss methods."

Eller uses the computer program to show farmers the value of their livestock manure and to help avoid potential environmental hazards from nutrient runoff.

Alan Sutton, Purdue animal scientist, says: "Today, environmental concerns and tight profit margins have forced livestock producers to re-evaluate their manure handling plans. Proper storage and applications on modern commercial farms are compatible with proper pollution control methods."

Jones says: "There has been a great deal of research on the proper use of animal manure, but programs that would make that research more usable at the farm level have been missing. That's what the Purdue computer program AMANURE does."

Why is manure so valuable? About 75 percent of the nitrogen, phosphorus and potassium fed to livestock is excreted in manure. For example, if a farmer feeds 100 acres worth of corn to his livestock in 1996, the manure by-product could fertilize up to 75 acres in 1997. At a cost of $45 per acre for petroleum-based, commercial fertilizer, assuming moderate P and K soil tests, that manure is worth almost $3,400 per year on 75 acres. On farms that have from 500 to 1,000 acres, that figure escalates to $22,500 to $45,000 per year.

"The program does a very good job of getting the necessary numbers together for a farmer," Eller says . "It helps with each year's analysis of fertilizer needs and it also helps a farmer understand just how much manure a livestock operation may generate."

Calculating the fertilizer value of manure isn't rocket science. But even if it is only manure science, it still takes a computer to do it accurately.

"Manure from chickens, cows, sheep and swine all have different nutrient levels," says Sutton. "Even manure from the same animals fluctuates in nutrient content depending on how the animals are fed and at what stage of growth they are in."

The storage method a farmer chooses can even affect the amount and concentration of manure nutrients. Water and bedding dilute the nutrient content of manure, and different storage techniques affect the amount of water and bedding added. For example, manure stored in a farm lagoon will have large volumes of water added, a liquid pit has only some spilled water added, and manure mixed with livestock bedding has the most water or urine absorbed.

As a result, farmers must test manure to find its true nutrient content, which means that farmers need to know some basic chemistry. That's not too big a task on most farms, where the phrase "N, P and K" -- which stands for nitrogen, phosphorus and potassium -- is commonly heard.

Once the farmer tests and really knows his manure, you'd think he would be ready to apply it to his fields.

But there's a lot more homework before he hooks up the spreader.

"The farmer has to know the fertility levels in the soil, the type of crop, and the amount of N, P and K that will be required to grow it," says Brad Joern, Purdue agronomist. Joern also says that all of this means nothing if the producer has not properly calibrated the application equipment.

Not all nitrogen in the manure will be available to the plant immediately. Some nitrogen is tied up, or bound, in organic forms and will become available to plants over time with the help of soil microbes. All this needs to be understood to realize the full value of livestock manure.

Sounds like you need a Ph.D. to manage livestock manure? Basically, it takes common sense and a lot of math. That's why Purdue developed AMANURE.

The program was developed for use on IBM-compatible personal computers with at least 512K of memory running on MS-DOS. Color graphics and a hard disk are not required. The program is distributed on a high- or low-density 3-1/2" or high-density 5-1/4" PC compatible floppy disk.

AMANURE is available from the Farm Building Plan Service ($15 to cover duplication, postage and handling) at Purdue University, 1146 Agricultural Engineering, West Lafayette, Ind. 47907-1146. For more information, call Kathy Brewer at (765) 494-1173.

Sources: Alan Sutton, (765) 494-8012; Internet,
Don Jones, (765) 494-1178; Internet,
Brad Joern, (765) 494-9767; Internet,
Gary Eller, (317) 566-3782

Writer: Steve Cain, (765) 494-8410; Internet,
Purdue News Service: (765) 494-2096; e-mail,

NOTE TO JOURNALISTS: Color photo of farmer Gary Eller available from Purdue News Service, (765) 494-2096.

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