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5 Steps to Manage Manure

It’s a gold mine of crop nutrients, but know what you are putting down.

Liquid manure is one of your least expensive and most beneficial sources of crop nutrients. Sadly, it’s often applied to cropland as an afterthought, something to get rid of.

John Yoder, vice president of waste-handling equipment at Eldon C. Stutsman, Inc., in Hills, Iowa, offers these five tips for maximizing the value of livestock manure for crop nutrients.

1. Start with storage.

Before pumping, properly agitate the manure in your storage tank to make sure you get it as uniform as possible.

“Otherwise, you will be pumping water off the top and sludge off the bottom,” Yoder says.

It typically takes four to eight hours of agitation to get a consistent slurry before you’re ready to haul to fields.

“You want it as equal as you can get it in nutrient quality,” he says.

2. Have samples analyzed.

Yoder thinks you should send manure samples to a testing lab for N, P, and K analysis.

Ideally, you’ll take three samples: at the beginning of hauling out, in the middle, and at the end. That will tell you how well you agitated it into a consistent slurry.

The N, P, and K analysis will help you at the next haul out or next year. (You may not get results back in time to help immediately.)

3. Place it correctly.

Yoder advises putting the liquid manure 6 or 7 inches deep. If you can’t do that, at least cover it on the surface. That helps prevent evaporation and runoff, and it puts it closer to the root zone, where it’s most efficiently utilized.

Use GPS guidance to eliminate overlap in application, Yoder recommends.

4. Control the flow.

A flow-control system can even out application of the manure to a uniform rate.

If you only let gravity control the rate at which the manure slurry flows through the injectors, you’re not going to get even application rates,” Yoder says. “When the tank is full, it flows out faster due to head pressure, compared with when the tank is almost empty.”

A flow-control device takes care of this issue by using a flow meter and a hydraulic valve. “The valve opens as needed to keep the application rate even,” he says.

Flow-control meters and valves are not inexpensive. Yoder’s company sells one that mounts on the outflow line of the manure tanker. It adds about $12,000 to the cost. “It’s worth it,” Yoder says. “You’ll use that tanker 10 years or longer, spreading the cost over hundreds and hundreds of loads.”

5. Pick a nutrient.

Apply manure at a rate that achieves the full, desired rate of your most limiting nutrient – N, P, or K – without overapplying the others.

Say your goal is 50 units of P per acre. When you apply at that rate, you only get about 50% of the N and 25% of the K that are needed.

“Apply for the full P rate, then balance the N and K with other fertilizer sources,” Yoder says.

Biggest mistake: no control

John Yoder of Eldon C. Stutsman, Inc. doesn’t hesitate for a moment when asked about the biggest mistake he sees in applying liquid manure to cropland. “It’s no control,” the waste-handling equipment expert says. “People don’t know what rates they are applying.”

It happens for a variety of reasons, he says.

“Maybe they don’t get a tank to empty out completely on one load. Or they have a lot of foam on a load. Or for some other reason, they just don’t get the tank completely full. They apply as if it’s a 5,000-gallon load, but they actually only put out 4,000 gallons. They’re 20% off from the nutrient level that they thought they applied.”

That’s where a flow-control device on the tanker really pays off, Yoder says. With the device, the rig will always run with the same manure rate flowing out to the applicator bar.

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