Nutrient experts believe it’s only a matter of time before surface application of manure becomes a practice of the past.
To be ready for that day, the Prairie Agricultural Machinery Institute in Humboldt, Sask., is working on a way to inject solid manure directly into the soil.
“That’s the key to the prototype machine we’ve developed here at Humboldt,” said PAMI engineer Hubert Landry.
“Injection is novel for solids, but we have demonstrated last summer that it can be done.”
Landry said the goal is to develop a machine that will inject everything that will not flow in a liquid slurry system, including feedlot manure, poultry and municipal waste.
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“In 2007, we had good success injecting some very pasty, sludgy manure,” he said.
“Then we did some compost manure that was very dry and that worked well, too. We also did poultry manure, which was really dry and that injected very well. So this thing works.
“We had a little trouble sometimes if there’s a lot of straw. It’s a little tricky at the injectors, but the augers still force it all through OK. It handles everything from composted manure to fresh manure right out of the feedlot.”
Landry said fresh manure has more liquid but the density of the compost is higher, so compost actually weighs more than fresh manure. Fresh feedlot manure is lighter because there are more air pockets. He said PAMI’s machine injects both of them easily.
“Our prototype isn’t nearly as large as a commercial field unit would be. The tank on this machine handles between 3,000 and 4,000 pounds of solid manure.
“With manure fresh from the feedlot, it’s lighter in weight, so we can only fit about 2,500 pounds in the tank.”
There has always been an underlying assumption that solid manure cannot be injected into the soil and that it takes massive horsepower to handle solid manure.
As a result, not much research and development has been applied to the problem.
Landry said PAMI wanted to prove that solid manure can be manipulated to the same degree as liquid manure and that it does not demand significantly high horsepower.
The floor of the bulk container has four hydraulically driven, open augers that push the bottom layer of solid material toward the rear of the box. The 12 inch augers run at the slow speed of 10 rpm. Together, they consume only 20 hp.
The four floor augers are driven at the front of the machine, while the four pillow block bearings at the rear of the box indicate their close proximity to the tank floor.
When manure reaches the rear, it drops through the first of two adjustable flow control gates. This first gate regulates the overall rate of material injected into the soil by controlling the total volume being dispensed.
The material drops through that gate onto a transversely mounted 12 inch transfer auger, which pushes the material left and right toward the far ends of the auger tube.
The bottom of the transfer auger tube has six ports, each one six inches in diameter. Each of these ports has its own adjustable galvanized steel slide gate to regulate the flow for that particular port.
“This is one of the strong points of our machine,” Landry said.
“It is amazingly uniform. We get equal distribution through each of the six openings because we adjust those galvanized baffles. They’re very quick to adjust.”
He said PAMI’s research has disproved the myth that it’s impossible to achieve uniform application with solid manure.
Moving the solid manure into position ready for injection was the easy part of the project. Figuring out how to inject it was a little more complicated.
Each of the six ports forces the manure into a sharp right hand turn, sending it back to the cultivator component. The manure squeezes through a cone that reduces the tube diameter from six inches to three.
“These cones sort of pressurize or compress the manure. Now that it’s in a three-inch pipe, we can inject it into the soil without being too invasive. The output ends of the cones are attached to flexible steel pipes that lead down to the soil.”
Landry said moving the compressed manure through the ripple walled flex hose was not easy without internal augers. It was possible, but required high horsepower.
“By pushing it through the three inch flex pipe, we were basically extruding the manure. It was sometimes binding up and it required tons of power. It just wasn’t feasible. So we tried flexible two and a half inch augers inside the three inch hoses. Now we had positive-driven manure and that worked.
“At first we had flexible augers on a cable that followed inside the flex hoses. Now we’ve straightened the flex hoses a little bit so we have our augers on straight steel shafts with universal joints where they bend. That works better.”
Landry said it may be a misnomer to call it true injection, which implies it is pressurized and blasted into the soil. Although the manure exits the three-inch tube with force, he said it falls into a trench opened by the 24 inch diameter disc.
“It’s maybe more technically correct to call it sub-surface application. We make a big trench, drop in the manure, then cover it all up right away with the 18 inch closer wheel.”
If the PAMI prototype proves that solid manure can be effectively inserted into the soil on a large scale without requiring high horsepower machinery, it paints a potentially brighter future for feedlots.
The project started in 2001 in conjunction with the University of Saskatchewan. The machine had been in the design and construction stage for two years and was tested for the first time in the spring of 2007 west of Humboldt.
The three-year field test will continue using a variety of solid manure, comparing the injector system to broadcast and broadcast with incorporation. Agronomic results will be released when available.
For more information, contact Landry at 306-682-2555, ext. 266 or e-mail HLandry@pami.ca.
