Novel rig sidedresses manure

12/15/2010 @ 10:17am

Hog manure is hard to handle, but it’s a very good source of crop nutrients. That keeps growers like Adam Wirtz searching for new and better ways to apply it.

Wirtz is the farm manager for a family-owned operation near West Bend, Iowa, that grows crops and raises hogs in confinement buildings. They plan to switch one of those buildings to organic hog production in the near future. Because they like to grow their own corn for their hogs, they have already started raising 200 acres of organic corn each year.

They can’t use commercial nitrogen to raise organic corn. Consequently, hog manure is a key part of their production system. The organic corn is raised in rotation with oats and clover.  After the oats are harvested, the clover grows up through the stubble. The clover is not harvested. In the fall, Wirtz applies hog manure to the clover and then rips the ground. Organic corn is planted the next spring.

Wirtz only applies a two-thirds rate of hog manure in the fall, however. “We feel like we lose some,” he explains. “We get a way bigger kick with that last one third if we wait and put it on in the summer.”

Three years ago, Wirtz modified a 16-row Hiniker cultivator to sidedress liquid hog manure in every other row middle. It was a fairly straightforward conversion. He cut the ends off the cultivator sweeps to make them less aggressive. They are now about 7 inches wide. 

“We didn’t want to move a lot of dirt,” Wirtz explains.

He also modified the folding mechanism so the cultivator wouldn’t hit the top of the tank when folded for transport. And because other nearby organic growers also use the sidedress rig, he built it so the outside sweep on each side can be removed to sidedress 12 rows instead of 16. It’s used on 1,500 acres each year.

Because of concerns about compaction, the family bought a relatively small 4,800-gallon tank and had the dealer install LandLuvr tracks. Those tracks are 12 feet long and 18 inches wide, so they really spread out the load. Wirtz uses tracked tractors, also.

The first year he had the sidedressing machine, Wirtz and his crew did it themselves. “But we just didn’t have the equipment it took to keep it running in the field,” he says. “We just had one small tank that could nurse it. And in addition to that, we were trying to spray and sidedress anhydrous ammonia on our conventional ground.”

In 2009, he turned the task of sidedressing over to Mike, Calvin, and John Bruellman, who run a custom manure application business at Ottosen, Iowa. The crews often run around the clock both in the fall and before spring planting, but they have a summer lull. “Since they had the equipment and the people, we let them take it over,” says Wirtz.

Bruellman has several 7,300-gallon tanks that he uses to nurse Wirtz’s applicator. For sidedressing, he widened the wheel spacing on a big John Deere wheel tractor to 120 inches to match Wirtz’s sidedressing rig and other field operations.

“Weeds will grow wherever you have compaction,” says Wirtz. “So weeds grow in our wheel tracks. We didn’t want an extra set of wheel tracks out there.”

Wirtz typically applies about 2,000 gallons of liquid hog manure per acre at sidedressing. He figures that supplies about 60 to 80 units of nitrogen.

“We tried 1,000 gallons, but with the 40-foot span, the application wasn’t as even as we would like,” says Wirtz. “There wasn’t enough volume for what we were trying to cover. When we bumped the rate up to 2,000 gallons, we were able to keep the tubes full and get a little more uniform coverage.”

The sweeps run 2 to 3 inches deep. “We’re just trying to cover the manure,” says Wirtz. “Because it is fairly dry then and because we are putting on such a small amount, it pretty well soaks right in.”

Even with good equipment, it’s still a big job.

It typically takes two nurse tanks to supply the applicator if they are working within 2.5 miles of a hog building site. Beyond that, it takes three nurse tanks. The Wirtz operation has enough hog sites that they rarely haul more than 3 miles.

Bruellman usually limits sidedressing to daylight hours, although the equipment was outfitted with an RTK guidance system after the 2010 season. That may make it more feasible to sidedress after dark.