May is generally a time when a lot of first-cut silage is saved. However, the weather has succeeded at putting that job on the backburner on many sheep farms.

Grass growth isn’t where it should be for this time of year and, for many, silage ground hasn’t been closed when it normally would be – and in some instances, silage ground has had to be regrazed.

However, the weather is out of our control, so all we can do is focus on what is within our control.

The words ‘good quality’ are thrown about a lot when it comes to silage and for good reason. Good or top-quality silage has been shown to reduce meal bills on farms – which is always one of the biggest operating costs.

So if we can make that extra effort when it comes to silage-making, we can go about reducing that meal bill next winter.

What can we do?

When closing paddocks for silage, it is important that paddocks or fields are grazed out properly, preferably down to a residual of 4cm to remove any dead material.

If ground is uneven, which is likely after the wet spring, it would be best to go in and roll closed-up silage ground, as well as anywhere on the farm that needs to be rolled for that matter.

This (rolling) is critical in terms of animal health for sheep. If clumps of soil make their way into silage, whether it be pit or baled, this will increase the risk that sheep that are fed this silage can ingest bacteria that causes listeriosis.

In terms of management of these closed areas for silage, it is vital to maintain soil pH, phosphorus (P) and potassium (K) at optimum levels.

In terms of fertiliser application, it is advised to apply up to 100-120kg/ha nitrogen (N) in the form of an appropriate compound or protected urea, allowing that about 30% of N previously applied for grazing will still be available to the plant.

Teagasc recommends not overdoing it with chemical N as this can cause lodging of the crop pre-harvest which will negatively impact digestibility.

When to cut grass

The ideal cutting date for silage would generally be mid-to-late May. However, this may not be possible on many farms this year with silage ground in some cases having to be grazed again.

Although, in spite of the weather this year, dry matter digestibility (DMD) silage can still be saved by cutting at a later date.

The target for cutting should be six to seven weeks after fertiliser application.

To best judge when grass is fit to cut, is by regularly inspecting it. What we want is to be harvesting grass when it is leafy before it heads out, and before the base of the sward starts to decay.

Delaying harvesting for too long will have a negative impact on quality as Teagasc says research has shown that for each week harvest is delayed, digestibility goes down by 3% units/week.

Keeping an eye on the weather is a must. Ideally, we want to mow grass on a sunny, dry day.

Going back to the point on the risk of listeriosis, don’t cut too low to the ground to avoid the risk of soil contamination.


The advice is to allow for a wilt period of 24 to 36 hours after mowing. Wilting for longer than this will reduce DMD by 0.5 to 2.0%, Teagasc says.

Teagasc also recommends to target 25% dry matter at ensiling for pit silage, and 30% dry matter for bales.


Ensuring the pit is covered properly and silage bales haven’t been damaged is of utmost importance.

In terms of the pit, ensure that it is fully covered and sealed as soon as possible after all the grass is stored.

Despite the increasing cost of bale wrap, extra layers of wrap, along with proper care handling while storing, will help to exclude air completely from the bale.

Damage to bales while transporting from the field to the yard is likely, so repairing as soon as possible is a must.

After silage is saved

Once silage is lifted and stored, it is important not to forget the impact that this has on P and K levels in that field.

A crop of silage can remove as much as 4kg of P and 25kg of K/t of grass DM harvested, according to Teagasc.

Therefore, replacing what P and K are lost with slurry and/or chemical fertiliser is a must.