Throughout the forage growing season many producers are putting up silage piles. To this point they have been predominately forages such as haylage or small grain silage; however, we will soon be moving into corn silage cutting season. This can become an extremely stressful and busy time of the year for producers, as they work to secure a high quality forage-based feedstuff during a narrow window of time. While quality is of utmost importance, making a pile that is safe for access should also be top priority.
Appropriate Size & Slope
As end product users of corn silage we know the ideal moisture content (60-70%) and particle size (1/2-3/4 inch) for adequate packing. What about the size and slope of the pile as we work to pack and build it? Many producers have made drive-over silage piles, although there are still those that prefer walled bunkers or upright silos. When considering the height of a bunker or drive-over pile, do not build it any higher than the unloading or defacing equipment can reach (typically 12-16 feet). Some payloader silage rakes however may reach a height of 28 ft. It is also important to maintain a minimum slope of 3 to 1 on the sides and ends of a drive-over pile (Figure 1).
This means that for every 3 feet of width there should be no more than 1 foot of height. To determine the size of pile needed for a drive-over the University of Wisconsin, Extension Forage Team offers an excellent Silage Pile Sizing Calculator spreadsheet for sizing your pile. There are a couple of reasons that this slope is important. First, this slope will minimize the potential for tractor rollovers. Secondly, it allows for better management and preservation of a large amount of forage by improving packing density and management at feed out. Lastly, there will be less spoilage loss as the sides and end are packed better.
Silage piles have become more dangerous as their size has grown progressively with larger livestock operations, which need larger quantities of forage available. Along with the slope of the pile there are also other danger areas that need to be considered when building silage piles or filling silos.
Figure 1. It is important to maintain a minimum slope of 3 to 1 on the sides and ends of a drive-over pile.
Equipment & Machinery
First, make sure that all packing tractors are equipped with rollover protective structures (ROPS) along with operators wearing seat belts. The ROPS and seat belt used simultaneously will help prevent the operator from being crushed and the operator being thrown in a tractor rollover situation. If a bunker silo is being used it is important that a guard rail be installed above the wall, and that it is visible to the pack tractor so that they do not go over the edge of the wall. Lighting is also recommended for bunker walls if packing is going to occur during the night. On steep slopes, tractors should be backed-up to prevent rollbacks or overturns. Four wheel drive tractors with push blades are recommended, with well lugged tires (typically dual tires) placed widely apart under the tractor, and weights placed on both the front and rear ends of the tractor. If a front end loader is used the loader should be kept low when full to help lower the center of gravity when moving silage.
Secondly silage packing is typically very chaotic and people can easily be run over or entangled in the equipment. There are many moving parts such as chains, PTO’s, belts and gears therefore personnel should not wear loose fitting clothing that could become easily entangled. Operators should always be mindful and not complacent of people who are in the area and account for everyone before taking off with dump trucks or push tractors or starting-up equipment. Children should never be allowed in the silage making area. If two or more pack tractors are in use establish a driving procedure to avoid collisions.
As silage piles are finished and employees work to cover piles the risk of falls increases due to the height of the piles and slippery surfaces from the plastic, especially if weather conditions turn wet. Care should be taken when placing tires and plastic on piles, working towards the edges from the center of the pile outwards. Extra care should be taken around edges as the risk of a silage collapse is greater in these areas. Workers should never be allowed to ride in loader buckets as piles are built or accessed at any time.
Avalanches are a serious risk when accessing the face of a silage pile as many people have been killed or injured when a silage avalanche/collapse occurs. It is very important to follow this rule of thumb: stand no closer to the front of the pile face than 3X its height. For example, if a pile is 15 feet high, you should be no closer than 45 feet from the front of the pile. Silage pile avalanches/collapses often occur when the pile has been improperly managed and silage is removed from the bottom up instead of the top down, resulting in an undercut and overhang in the pile. These overhangs can collapse at any time and workers or people accessing the pile should not be complacent regarding avalanche risks. Samples should only be taken from silage that has been recently removed from the pile in a loader bucket or a fresh silage pile that is located a safe distance from the face of the pile. It is recommended to place warning signs regarding the avalanche/collapse risk for silage piles along with possibly fencing off the area to limit access to this high risk area.
Gases are produced during the silage fermentation process and can be present for up to three to four weeks or more after the ensiling process is complete. The most dangerous gas produced is nitric oxide which changes to nitrogen dioxide (NO2) when it comes in contact with oxygen. Nitrogen dioxide is an extremely toxic gas which can cause death. It is a strong acid which when breathed in burns the lung tissue stopping the flow of oxygen to the body. Its presence can be noted by burning sensations in nose, throat and chest. This gas is often found in higher concentrations in upright silos and is often referred to as “silo gas”. It is recommended to ventilate a silo when first opening it after harvest to release the gas present. It is recommended to use the buddy system (working in pairs) when working around silage piles, especially those being accessed for the first time.
The Bottom Line
Accidents involving silage piles are often preventable. Workers need to be trained how to properly use machinery when building and accessing silage piles or putting silage in silos. We cannot risk becoming complacent in this high risk area but instead need to always be vigilant and aware of the potential risks regarding silage piles and silos used for feed storage.