sealPurdue News

July 1997

Hi-tech manure spreader latest precision farming development

WEST LAFAYETTE, Ind. -- A liquid-manure applicator under development at Purdue University can be incorporated into a precision farming setup that uses computer-directed equipment and satellite-oriented GPS (geopositioning) technology.

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The hi-tech manure applicator is the first of its kind in the nation.

This isn't a load of you-know-what.

Manure is unpopular stuff, even with farmers. It does provide valuable nutrients at an affordable price, but the packaging leaves something to be desired. As a result, many farmers have opted to use man-made chemicals instead of manure.

Stephen Hawkins, assistant director of the Purdue Agricultural Centers and co-developer of the precision manure applicator, says many farmers have avoided zeroing in on manure application for a variety of reasons. "The fertilizer dealers don't want to mess with it. There is a large amount of government regulation. And misapplication can damage crops and the environment," he says.

Dan Ess, associate professor of agricultural engineering and one of the developers of the precision manure spreader, says the lack of equipment played a role in this situation, too. "Proper manure management has been ignored by many farm producers because the equipment hasn't been there to make it part of a high-speed, high-acreage operation," he says.

Proper record keeping on manure is also important because, unlike chemical fertilizer applications, manure releases its nutrients slowly as it degrades. "What we're trying to do is to make sure the nutrient value is properly credited," Ess says. "The nutrient value for the field will increase after the manure is applied, but it will also be increased to varying degrees the second and even the third year after application because of the gradual decay and release of nutrients by the organic materials." The complexities of manure application mean that proper accounting of nutrient values and the application locations are critical information that needs to be captured.

Moreover, several states now require that farmers prepare management plans for chemicals and manure to avoid contamination of the environment. Current manure handling equipment makes such paperwork difficult. "It used to be that a farmer would go out and apply 20,000 gallons of manure without having records of where he put it," Ess says. "That doesn't work for a comprehensive nutrient management plan."

The Purdue team, which also includes research assistant Keith Morris, addressed this problem by converting a standard liquid manure spreader into a hi-tech piece of equipment that will fit into today's highly computerized and highly regulated farm. They began by taking a standard liquid manure application wagon and adding some additional parts, such as a vacuum pump (which is in addition to the original slurry pump), an agitator, and, the key piece of equipment, a flow measurement system.

"The meter is a rugged electromagnetic device with no moving parts. It's a common piece of equipment in municipal sewage treatment plants," Ess explains.

According to Hawkins, the conversion will be simple enough that any farmer who is interested in precision manure application will be able to make the system work. "You add $5,000 worth of equipment to a $12,000 to $15,000 manure applicator," Hawkins says. "If you've already got a precision farming setup -- including an electronic applicator controller -- and a tractor, you're in business.

"If a farmer has GPS equipment, this is a way to spread the cost of precision farming over another operation. The economists here will tell you, precision farming will work better economically if you can spread the expenses across more parts of your farming operation."

Precision farming is a collection of technologies that links geopositioning equipment, computers and variable-rate application farm equipment to deliver varying amounts of fertilizers or pesticides to different parts of the farmer's field, depending on the needs of that particular site. Now, with a manure applicator that can map the application location and rate, manure also can be included in precision farming systems.

Besides the relatively low expense, the researchers say the equipment necessary for the conversion is small enough to fit into the cab of a pickup. All the equipment is used in other applications, so it is available off-the-shelf. "It just requires minor physical modifications," Hawkins says. "Then you just need to spend one or two days in a shop welding it on."

Besides these modifications, the Purdue manure applicator has had the wheels set to accommodate 30 inch rows so that it is possible to side-dress standing crops. Also, so that the researchers could make sure that the electromagnetic flow meter worked in this application, they used a load cell and readout meter to precisely measure the weight of the manure. "So far the flow meter has been very accurate, more accurate than it needs to be, in fact," Ess says.

"It's important to realize when you see our applicator that we've added all of this testing equipment. What the farmer would end up with in the field wouldn't be nearly this complex."

Because of increasing environmental regulation, Ess says that the development of the equipment was important for farmers. "We're making sure that the farmers can do what they know they should do. That's the role of a land-grant university," he says.

Sources: Dan Ess, (765) 494-6509; e-mail,
Stephen Hawkins, (765) 494-8367; e-mail,
Keith Morris, (765) 494-1187; e-mail,
Writer: Steve Tally, (765) 494-9809; e-mail,
Purdue News Service: (765) 494-2096; e-mail,

Photo caption:

Purdue agricultural engineers have developed a precision manure applicator that uses computer-directed application and GPS technology. The hi-tech manure applicator will allow farmers to more easily control nutrient application and to keep records for environmental management plans. (Purdue Agricultural Communications Photo by Mike Gibson.)

Color photo, electronic transmission, and Web and ftp download available. Photo ID: Ess/Spreader

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