Maize for Silage
Insight 311


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The optimum drymatter percentage for ensiling maize silage is 30 - 38%.  However weather conditions in some seasons mean that in practice, some crops will be harvested at above 38% drymatter.  This can have implications on both maize silage quality and how easy the crop ensiles.

The effect of increasing maturity on the yield and quality of maize silage depends on a large number of variables including the hybrid, the plant population and the growing environment.  We know that:

  • Maize grain yield increases up until the plant reaches physiological maturity (also known as black-layer).  The whole plant drymatter at black-layer depends on the stover drymatter and the cob-to-stover ratio however it is normally around 42-44%.  The increasing grain content has a positive effect on starch levels and the crop’s feed value.
  • As stover (stalk plus leaf) drymatter increases, feed value of stover slowly decreases due to the decrease of cell wall (NDF) digestibility.
  • Somewhere between 38% and black layer, the increase in feed value due to the accumulation in grain is partly offset by the decrease in stover feed value.
  • After black layer, feed value and yield decrease due to a loss in the quality and quantity of stover.

The main point to remember is that maize silage feed value changes gradually and a well-managed dry crop can still have an excellent feed value.  One of the main problems with a dry crop is achieving adequate compaction to ensure a good fermentation and minimal aerobic (oxygen present) spoilage at feed-out time.

It is important to determine the cause of the high drymatter. If the plant is dying due to disease, frost or drought it is likely that the high drymatter is a result of a dry plant. Chop length will need to be shortened to account for the dry plant.

If, however, the season results in a lot of grain being produced, the dry matter of the silage will be higher and the quality of the silage is likely to be excellent due to the high grain content. In this case there may be no need to adjust chop length, but it is likely that there will be a need to adjust the kernel processor gap.


The following guidelines will aid in achieving a successful fermentation of dry maize silage crops. 

Reduce chop length

A fine chop length releases more plant fluids. Crops that are drier will need to chopped shorter. Use the squeeze test to determine the correct chop length.

The “squeeze” test

A good method of testing whether the chop length that you are using is correct for the moisture level is to take a handful of the maize silage and squeeze it. The palm of your hand should feel moist after applying pressure. If you can squeeze water out of the silage, you are almost certain to have run-off from your stack. Request that the chop length is increased and the processor backed off, then retest. If no improvement is gained when the machine is set to maximum chop length, either cease harvesting and wait for the crop to mature further or contact your local Pioneer representative toll-free on 0800 PIONEER (0800 746 633) for information on ensiling a wet maize silage crop.   

If there is no moisture evident when you squeeze a handful, and when you release the material it does not stay compressed, the maize is too dry and/or the chop length is too long. Request that the chop length is shortened and the processor gap is checked. If the machine has reached its minimum settings and no improvement is gained, special steps must be taken to ensure a good fermentation takes place. Contact your local Pioneer representative toll-free on 0800 PIONEER (0800 746 633) for information on ensiling a dry maize silage crop.

Ensure your contractor runs a plant processor

As the kernels become more mature, they are more likely to pass through the cow undigested.  Plant processing improves kernel starch digestibility by breaking the hard exterior of the kernel, increasing the surface area and allowing better access to the rumen microbes.  Aim to have 99% of the kernels cut into quarters (with a target of min. 80%).

Use a Pioneer® brand silage inoculant.

Dry crops often have higher levels of mould and yeast spores and they are harder to compact leading to an increased risk of a poor fermentation and heating at feed-out

time. Applying Pioneer® brand 11C33 maize silage inoculant at harvest time will help ensure the silage ferments well and remains cool for longer at feed-out time.

Maximise compaction

As drymatter increases a greater consolidation effort is required to achieve a good compaction.  The use of more vehicles, heavier vehicles, a greater rolling time or a combination of these factors is recommended.  Make sure that the maize silage is spread into thin layers, which are easier to compact.

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The information in this publication is general in nature only. Although the information in this publication is believed to be accurate, no liability (whether as a result of negligence or otherwise) is accepted for any loss of any kind that may arise from actions based on the contents of this publication.

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Revised: Jan 2020
Expires: Jan 2022