Grass and Legume Silage Tips

There are many potential reasons why grass silage may end up with an undesirable fermentation. Below is a list of common issues that arise during the process of making grass and legume silage and potential causes and solutions.

Reheating/mold immediately underneath the film

Holes in the film e.g. caused by animals or weather
Plastic with insufficient oxygen penetration protection
No oxygen barrier
No large tires or sandbags on plastic edges

Silos should be wide enough to allow parallel unloading and packing of loads.
Silos without side walls need to be designed wider, as the silage pile becomes narrower towards the top.
Fill by layers. Each layer should not be thicker than 6 inches, as greater thicknesses make it more difficult to pack the silage efficiently.
Avoid unloading silage in piles in front or on top of a silo as it makes adequate packing particularly difficult. The extra time needed for spreading the large piles out can then be used for additional packing.
Ensure that packing is performed as evenly as possible across the full surface. Having another tractor and driver available for pulling vehicles on top of the silage can be particularly useful.

Reheating/mold at the upper silo face

Inadequate packing and compaction
Improper packing (chop length, deposited layer sizes) and silo geometry do not match

Improve packing and compaction, including chop length, pile planning, and depth of layers being packed
Improve face management

Reheating/mold about 6-8 inches below the surface

Excessively deep layers deposited at the top during packing
Silage layer excessively contaminated with soil and dirt
The top layer can be unaffected due to it being too cold for molds and yeast to grow

Max 6 inch layers during packing
Maximize compaction and increase packing density
Avoid bringing in more ash (soil and manure) from the field.

Reheating/mold in the middle of the silage

Excessively high DM layer, or old excessively wilted material
Excessively deep layers deposited at the top during packing
Insufficient chop length

Max 6 inch layers during packing
Avoid introducing over-mature and/or excessively wilted material into the middle of your silage: instead ensile separately or deposit in thinner layers at the very bottom of the silo

Reheating/mold randomly distributed

Insufficient chop length or distributed over-mature material (in combination with inadequate packing)
Inconsistent silo filling and/or presence of cavities (trapped air)
Harvesting residue from a previous cut – inadequate management

Chop overly mature material shorter
Fill silos evenly and avoid air pockets or “cavities”
Avoid picking up material from previous cuttings

Reheating/mold around the edges

Incorrect filling of silo bunks (sloped outside edges)
Poor compaction along edges

Pack right up to the silo wall
Use sidewall and oxygen barrier plastic

Silage smells of butyric acid

High contamination of ash (from soil and manure)
Improper fertilization: a shortage of nitrate in plants as a natural inhibitor of clostridial growth during the ensiling process

Improve harvesting hygiene, reduce soil and manure contamination
Adjust fertilization
Review silage additive use

Rotten, slimy layer on the surface

Holes in plastic film, e.g. caused by animals or weather
Long delay in covering silage
Pockets of air between the plastic and silage

Cover the silage as soon as packing is finished
Use an oxygen barrier
Use a thicker main plastic
Use silage netting or tarp to protect against mechanical damage