Guard against silo gas dangers


GREEN BAY, Wis. – While the tower silo offers many benefits, there are also some inherent dangers that need to be minimized.

Of these, silage gases may be the most hazardous. People and farm animals have died from the poisoning of nitrogen dioxide, the most dangerous of silo gases.

Lethal gas.

Nitrogen dioxide is a lethal gas with a yellowish-brown color and smells like some laundry bleaches. When this gas achieves further oxidation and is then combined with water it becomes a highly-corrosive nitric acid. Since oxygen and water are highly available in the body, this gas can be extremely dangerous when inhaled.

Nitrogen dioxide is heavier than air and will remain at the bottom of the air mass over the silage. It can also settle down through the chute or the drain at the base of the silo. It often concentrates in the feed room and moves into the barn.

It may leave a yellow stain on silage, wood or any other material it contacts. Other indicators include dead cats or mice on the feed room floor, or dead birds in the silo.


There are several factors that affect the silage’s ability to produce nitrogen dioxide. Prolonged summer droughts followed by rain just before harvest, high levels of nitrogen in the soil, unfavorable growing temperatures, prolonged cloudy weather, and root damage all increase the likelihood of nitrogen dioxide problems.

Some of these causes are unavoidable particularly during drought. However, proper fertilization, combined with proper weed, insect, and disease control measures, will reduce the chances of producing excessive nitrogen dioxide at the time of ensiling the crop. Because most nitrates are stored lower in the stalk, cutting higher than normal, 10-12 inches for corn, can reduce the amount of nitrates.

Take precautions.

The majority of the gases will be produced in the first 5-8 days and there are several precautions that should be taken. First post warning signs near places like the silo chute, feed room door, or outside ladder.

If these signs are not presently in place, they are available from your local International Silo Association member company. Also, ventilate the feed room in case gas spills out of the silo doors, or is blown out by the unloader. Keep the door between the feed room and the barn closed to prevent nitrogen from killing livestock. If the silo must be entered, do not enter it the day after filling, instead do so immediately after last load is finished, and be sure to ventilate the silo properly.

For complete instructions on proper ventilation, contact your local tower silo dealer, or see your silo operator’s manual.

The risks involved with the use of tower silos do not out weight the benefits of low storage losses and ease of operation. Many elements on the farm present dangers, and we accept them. Using proper precautions and having knowledge of the problems that are presented in each situation can help to minimize the dangers.

For more information regarding silo gases, contact your local ISA member or the ISA office at 630-258-7206.

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Preventative silo maintenance

GREEN BAY, Wis. – At first glance a tower silo may look indestructible, but this is not the case.

However, if the silo is properly taken care of it will likely remain an extremely helpful element on your farm for years. The following are preventative maintenance tips that should be performed regularly on your tower silo.

1. Clear away any debris that may have accumulated around the base of the silo.

2. Make sure all silo drains are open.

3. Make sure any drainage effluent does not enter any surface waters, waterway, or field drainage system to cause a pollution problem.

4. Check the condition of the exterior wall surface for cracks, holes, seepage erosion, etc.

5. Check for erosion of the top of the foundation wall.

6. Check the condition of the interior wall surface: softening and pitting, holes, etc.

7. Check the condition of the door jambs.

8. Check for loose, corroded or broken hoops. Have the hoops retightened at regular intervals.

9. Check for corroded tie rods or bars across the doorway.

10. Check the condition of all ladders and the means of fastening in place.

11. Check the condition of the safety cage and platform.

12. Check to make sure the fill-pipe is straight, tightly fastened and in good condition.

13. Makes sure the silo roof is sound, straight, tight, and properly fastened in place: top hoop and clips all tight.

14. Check the distributor for wear, lubrication and adjustment.

15. Check the condition of the unloader lifting winch and cable.

16. Check the condition of the silo chute.

17. Check to be sure unloader is properly greased and follow all safety instructions when performing maintenance.

18. Check the condition of all silo doors and door related hardware: hooks, latches, etc.

Performing the above maintenance checks should keep your silo in good working order, as well as provide safe working environment for those who work in and around the silo. If you have any other questions on routine maintenance contact your tower silo contractor or the ISA office at 630-253-7206.


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