In 2016, this dairy silo collapsed in southwestern Missouri. Following drought last year, many silos are empty, providing an opportunity to inspect silos, says University of Missouri Extension dairy specialist Reagan Bluel. (Photo courtesy Murray Bishoff, The Monett Times.)

Many dairy producers are starting the silage season with empty silos this summer, says Reagan Bluel, dairy specialist for University of Missouri Extension. That presents a good opportunity to inspect those silos for problems.

Producers turned to silage stockpiles this winter to feed cattle after the drought of 2018.

Tower silos, designed to store chopped fermented silage, are at risk due to age and use. Concrete and steel corrosion compromises the structural integrity of the silo. “As a result, tower silos in disrepair may collapse because they can no longer carry the design loads caused by the stored forage,” says MU Extension agricultural engineer Joe Zulovich.

Empty silos are easier to inspect for structural damage than those being topped off, says Bluel.

“Now is the time to make a visual check of the entire exterior for cracks and settlement,” she says. “Additionally, check interior sidewalls for cracks and degradation. If you can see daylight through a tower silo wall, you have a tower silo that is likely structurally compromised.”

Check the silo discharge door, roof and wall openings for sagging, she adds. Roofs can receive damage from overfilling, vibrations and the environment. Check regularly.

Climb into the silo and inspect sidewalls for cracks and bulges. Wear a mask to prevent breathing issues in the confined space.

Immediately make a plan if you find faults. Consider treating surface problems to prevent collapse, or using alternative storage for the 2019 silage crop. Perform regular preventive maintenance.

During her work with dairy farmers in southwestern Missouri, Bluel finds that leaning silos usually collapse within 24 hours. This puts lives and crops at risk. Proactive inspections reduce the likelihood of injury and costly cleanup. Zulovich notes that many silo failures are not included on insurance policies.

Be sure to harvest corn silage at the correct moisture, Bluel says. “If harvesting forage when it is juicier than ideal, as the feed ferments, the excess leachate containing acid from the silage will eat away at the concrete walls and foundation and weaken silo structure.”

Bluel says it is important to train new workers on the correct way to blow silage or green fodder into the silo.

Teach workers to blow silage using a silo forage distributer to evenly spread forage or blow forage exactly into the center of the silo to evenly load silo walls. Uneven loads on a tower silo wall will likely cause the silo to collapse. Teach workers how to properly unload the forage wagon and monitor the silo blower. Use fall protection and work with a partner, particularly during harvest season, Bluel says.

Bluel recommends “Deterioration of Concrete Tower Silos,” a fact sheet from the Ontario Ministry of Agriculture, Food and Rural Affairs, available for download at omafra.gov.on.ca/english/engineer/facts/08-057.htm.

(1) comment

John Carson

While I agree that inspecting a tower silo while it is empty is preferable to doing so when it has silage, grain or some other bulk solid inside, the advice given by the author is so superficial that it could result in personnel being placed in danger of serious injury or even death. First, a tower silo is almost always a “Confined Space” as defined by OSHA 29 CFR1910.146, i.e., a space that has adequate size and configuration for employee entry, limited means of access or egress, and is not designed for continuous occupancy. Although a farm that employs ten or fewer workers and does not maintain a temporary labor camp is exempt from OSHA regulations, it’s wise to pay attention to what they require for larger farms and industrial facilities. A permit-required confined space (“permit space”) presents or has the potential to present an atmospheric hazard, an engulfment hazard, a configuration hazard, and/or any other recognized serious hazard. Simply donning a mask to prevent breathing issues, as the author recommends, is not sufficient. General requirements for a permit-required confined space include:  Posting danger signs  Developing and implementing a written permit space program that includes: o Preventing unauthorized entry o Identifying and evaluating hazards before employees enter the permit space o Developing and implementing means for safe permit space entry o Providing and maintaining testing and monitoring equipment, communications equipment, PPE, barriers and shields, equipment for safe ingress and egress o Rescue and emergency equipment Second, a silo may be structurally compromised even though one cannot ‘see daylight’ through its walls. Furthermore, a leaning silo may collapse sooner than 24 hours, or it may stand for weeks or months. In addition, it may take more than “treating surface problems” to prevent silo collapse. Each year hundreds if not thousands of individuals are severely injured and many are killed when working in and around bulk solids storage and handling facilities. While this represents but a small percentage of all fatal occupational accidents reported by OSHA and other government agencies, these accidents often receive more press coverage and, in many cases, are avoidable for reasons explained in a recently published paper that I co-authored. (“How to reduce safety risks when storing and handling bulk solids”, Powder & Bulk Solids, March 2019, pp. 12-16) Tower silos must be treated with respect, and, as stated in the article on deterioration of concrete tower silos referenced by the author, “If you suspect that your silo has structural problems, do not fill or empty it before having a professional engineer on-site to evaluate the situation.” Furthermore, “do not undertake [converting a silage silo to dry grain storage] without professional advice." John W. Carson, Ph.D. Chairman of the Board Jenike & Johanson, Inc. 400 Business Park Dr. Tyngsboro, Massachusetts 01879 978/649-3300 jwcarson@jenike.com

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