Farmers and agronomists joined forces recently at Echuca to discuss management strategies to optimise the quality of winter cereal silage.
Speaking at Murray Dairy’s Accelerating Change Successful Winter Cropping workshop, agronomist Luke Nagle and silage consultant David Lewis highlighted the agronomic considerations for the end of the season and the importance of good decision-making and management to maximise return on investment and the quality of the end product.
Mr Nagle emphasised the importance of maintaining good management after the final grazing of cereals, keeping in mind the likely return in yield and quality for your investment.
It is critical to stop grazing before stem elongation and grazing after this time can reduce silage yields by up to 50 per cent.
After the final grazing is a good time to revisit your crop nutrient and water requirements and monitor the seasonal conditions and irrigate prior to stress for the best return on water.
Cereal plants are particularly prone to stress during pollination and flowering which can have a significant impact on grain yield and quality.
As you are coming to harvest, consider fungicide requirements for whole crop silage or hay, bearing in mind any withholding periods. Work with your agronomist to get management right, ensuring that you avoid any mistakes at the last minute that could compromise the final product.
Timing of harvest
Mr Lewis spoke about the importance of planning for timing of harvest right from the beginning.
Being really clear on what product you are trying to achieve and how this fits into your feeding system before you put anything in the ground is critical to ensure you get what you want at the end.
There is a compromise between feed quality and yield, and protein and starch, so knowing what you need in your feed budget will ensure you can utilise the end product most effectively.
Both Mr Lewis and Mr Nagle highlighted the importance of selecting a species and variety that is going to fit your end goal.
Think about the end goal for the crop, how much growing season you expect to have, and select early, mid or late cultivars accordingly.
Whole crop cereal silage can be cut at two stages of growth:
1. Flag leaf-boot stage: Lower yield, generally higher metabolisable energy (ME) and crude protein (CP).
2. Late milk-soft dough stage: Higher yield, high starch, variable ME, lower CP.
Timing of harvest needs to be matched to which of these silage products you are trying to achieve, what seasonal conditions are like and actual development stage of the crop.
Worst case scenario is if both windows are missed and crops are cut somewhere in the middle. This can lead to a compromise on yield as well as quality.
Once target growth stage has been selected, each silage type must be managed accordingly.
Flag leaf-boot stage silage needs to be wilted similar to pasture silage. Dry matter targets should be around 33 to 40 per cent for a stack or pit.
This can be difficult as this growth stage is early in the season. Big, wide, fluffy windrows can assist to achieve the right level of wilting. Silage additives are essential if the crop is not wilted enough.
Late milk-soft dough silage can be directly cut without wilting as it can, pending seasonal conditions, dry to an appropriate level standing.
Dry matter should be around 36 to 42 per cent. Direct cutting can be advantageous, particularly if it is dry, to reduce dust and if cereals have been sown into cloddy paddocks.
Responding to seasonal conditions
Even if you have clearly defined goals from the start, harvest timing doesn’t always go to plan. Particularly in northern environments, harsh climatic conditions can mean crops run out of moisture sooner than planned.
As the season progresses, keep checking back and considering crop development. Can you still achieve your goal? If you are aiming for late milk silage, will the crop make it? Assess and manage accordingly.
Mr Lewis spoke about the need to proactively monitor the dry matter of the crop.
In the Murray Dairy environment, moisture content can change very rapidly, particularly if there is a run of hot north-westerly winds.
As cereal crops run out of soil moisture they begin to draw moisture from the bottom of the plant to fill the head. To check moisture content, break open the stems of mature crops. They can be hollow and dry, even if the crop still looks green from above.
In particularly dry years, parched grains won’t soften and are hard to process as the soft sugars are all converted to starch. It is important to time harvest of wheat and barley to avoid this, and not go in too late.
This window can close very rapidly, within seven days for barley. In dry years you may need to strike a balance between whole plant moisture and grain filling.
Pack and seal immediately
Mr Lewis highlighted the need to pack and seal immediately to ensure silage quality. Whole crop silage expands very quickly, much more so than pasture. This is because it has drier, hollower stems than pasture.
It needs to be rolled and sealed as the pit is being filled so that it doesn’t expand and take on air. Also be aware that cereals can be over-rolled. If this has occurred cereals will slip out the bottom of stacks and it is extremely difficult to get them back in.
Silage density has a big impact on fermentation, so getting it right is critical to optimising quality. As well as packing it right, density is also related back to dry matter percentage at cutting time.
A lot of dry, hollow stems will make the silage spongy and difficult to compact. A sign that the silage may have been too dry at packing time is if it feels wetter than it should
in the stack at feed-out.
This is a possible sign of yeast activity in the stack, as water is a by-product of their action. The silage will also have a sickly sweet smell to it.
Harvesting at the best dry matter possible for the season, and packing and covering it quickly, will give the crop the best quality when it comes out of the pit.
Monitor and measure to get it right
When it comes to ensiling, monitoring and measurement is the only way to accurately know if you are on track to achieving the product you want, and can help you fine tune your management decisions in-season or for next season.
Mr Lewis provided techniques for measuring dry matter and stack density and emphasised the value of checking crops during growth and at harvest.
Checking stack density as you build will allow you adjust processing as required to achieve a better result.
If packing density needs to be increased, try:
- a shorter length of cut;
- adding more packing tractors;
- increasing tractor weight;
- reducing layer thickness; or
- slowing the rate of harvest.
Keep records of what is going into the stack. A diagram will assist you to know exactly what is coming out of the stack when feeding out, and what rations may have to be adjusted to compensate for differences in quality.
For the optimal result when it comes to winter cereal silage, plan ahead, manage for your feedbase needs and get out into the paddock to check your crop regularly.
Measure your crop performance and silage quality rather than guessing it. Work with an agronomist and maintain good relationships with your contractors to ensure that you end up with the best feed for your herd.
More information and resources from the workshop are available at: www.acceleratingchangeproject.com
• By Amy Fay and Harriet Bawden, Accelerating Change, Murray Dairy