“Edible” bunker silos may enable Wisconsin livestock farmers to save labor and money when storing and feeding forages.

University of Wisconsin-Madison researchers devised a low-cost system for storing corn silage and hay during a research and demonstration project at the Hayward Agricultural Research Station. The five-year project focused on labor and cost-saving practices farmers could adopt to maximize profit on a beef/sheep and forage farm. The primary goal was to determine if such an operation could support a family in northern Wisconsin.

The problem of storing surplus silage

During the past 40 years, Wisconsin farmers have learned that storing forage crops such as corn silage and hay reduces weather and field losses while preserving yield and quality. In addition, farmers often have more silage than their conventional storage structures can hold.

Across the United States, forages make up 93 percent of the rations for beef cows. Twenty percent of that amount comes from stored forages. Hayward researchers budgeted 50 percent of feed from stored forage.

“Storing forage crops in edible silos is a short-term insurance practice that will provide adequate and quality forage for livestock,” says Dwayne Rohweder, UW-Madison emeritus professor of agronomy. “This storage-feeding system greatly reduces the amount of labor used in feeding the herd.”

Emeritus UW-Madison animal scientist Art Pope directed the project, which ran from 1985 to 1990. Day-to-day operations were carried out by Deb and Bob Huntrods, with consultation from Rohweder and Rudy Erickson of UW-River Falls. UW-Madison emeritus agricultural economics professor Bob Luening conducted the project’s farm business and financial analysis.

Corn silage was used as the beef cow’s major winter food supply. The researchers planted 40 to 60 acres of corn for silage each year in the fields designated for renovation or re-seeding.

Cones and bunkers: low-cost handling alternatives

During the project’s first year, silage was piled up in cone-shaped stacks using a 50-foot grain elevator. The silage was not packed. By spring, each stack had six to eight inches of spoilage around the outside. Beef cows ate some of the spoiled silage, but about 10 percent was wasted. Farm operators had to feed silage and hay daily.

In subsequent years, the Hayward researchers stored corn silage in bunker silos between two long rows of 1400-pound round bales. The big bales were draped with plastic, which extended several feet onto the ground inside the bunker.

The work crew packed the silage with a tractor and wagon as they filled the silo. The first silo was 24 feet wide; later silos were 35 feet wide, which made packing easier and safer. The crew filled and packed rapidly, then covered the silage with plastic weighted down with tires to reduce spoilage.

“Livestock producers can change the proportion of legume hay to corn silage in the ration by increasing the rows of bales in the side walls,” Rohweder says. Later silos used two rows of bales on one side of the silo to get more grass-legume forage in the ration.

The crew stored the silage in a protected area on a pastured field with a sloping, well-drained soil. The design permitted cows to be kept in the open and to feed right out of the bunkers, saving labor and money. Manure was kept in the open where it could more easily be spread on pastures.

The crew stretched an electrified barbed wire attached to a wood feeding gate across each end of the bunker. They moved the gate as needed, usually every two to three days. Self-feeding started in November and was completed by early March while the ground was still frozen. Wastage averaged about 10 percent, more on the up-slope than the down-slope.

Researchers at the Spooner Agricultural Research Station have developed a more permanent silage storage system. They store fall-harvested legumes and corn silage by blowing the forages into the front of treated wood trench silos. The crew tries to keep silage from each load as level as possible, using a small tractor to pack the silage after each load. Black plastic held in place by fence posts covers the silo. The crew feeds silage daily in feeders to ewes.

Low-capital corn silage handling recommendations

Rohweder offers the following recommendations on storing and making quality corn silage:

• Construct and size horizontal silos to seal the sides and provide the amount of silage needed each feeding period. Silage must be filled rapidly, packed well, sealed carefully, and immediately covered to reduce spoilage losses. Silage inoculates in the top 1 to 2 feet help reduce spoilage and extend silage bunk-life. Store silage in bunker silos at moisture contents of 62 to 68 percent.
• To produce top quality silage, plant a hybrid that will mature in your area. Farmers can increase silage feed value by 5 percent by leaving an additional foot of the lower stalk in the field when chopping.
• The best grain hybrid is not necessarily the best silage hybrid, says Rohweder. Silage quality varies partially because of the grain. Stover also varies widely in fiber content and digestibility. For operations that desire high animal performance, select a hybrid having high forage digestibility and intake potential.
• Match plant population to soil fertility and water-holding potential as well as fertility supplied to the crop. UW-Madison trials with corn populations up to 30,000 plants per acre did not change silage quality.
• Harvest silage in early dent or at half-milk line. Chop at one-fourth to three-eighths theoretical cut for best packing and for the rumen to function properly. You can improve the quality of big bales used as side walls by storing or placing them on gravel or concrete. Studies show this will reduce storage losses by 25 percent.

The Hayward project showed that a beef/sheep enterprise is not competitive under most Wisconsin conditions. However, such a farm can provide a modest source of supplemental income if the farmer keeps debt low, manages carefully, and is willing to work for modest wages.

Contact CIAS for more information about this research.

Published as Research Brief #8
February, 1993