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Grow the future | Grassland Sulphur Grow the future | Grassland Sulphur

Spreading nitrogen and sulphur at the same time means more grass

Applying fertilisers containing nitrogen and sulphur means the grass uses nitrogen more effectively, you get more kgs of dry matter per kg of nitrogen that you apply

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Fertiliser application advice for first cut silage crops

Remember grass will start heading out at the same time as usual, so allowing a longer first cut growth period might be okay to increase grass silage yield for some but the quality of this silage will be lower. Also, the second cut regrowth will be slower, so while you might gain extra yield on the first cut, you will lose out on first cut quality and second cut yield.

When it comes to early May, check the base of the sward for dead/decaying leaf and stem. What happens at the base of the sward has as great an effect on feed value as seed head emergence. This dead decaying material might be as a result of water logging or just the wet conditions especially where there were heavier covers of grass on fields and in some cases this grass has lodged whereas in other years it mightn’t have. If there is dead material at the base, then consider cutting sooner rather than later.

There are a couple of first cut scenarios being faced by farmers presently:

1. Fertiliser and slurry have been applied, but the grass looks backward and isn’t a lush green colour.

Grass growth has been affected by wet soil conditions and overcast weather. Nitrogen losses to leaching will have been greater due to the above average rainfall this spring, but putting a figure on this is very difficult. Should more nitrogen be applied in this case? It will depend on when the slurry and fertiliser was applied. If slurry applications were applied in Jan/Feb and fertiliser was applied before the 20th of March, then an application now of 125 kg/ha of YaraBela Nutri Booster (1 cwt/acre) is justified if the anticipated mowing date is circa 20th of May.

2. Slurry has been applied but not the nitrogen fertiliser.

If applying nitrogen or an NPK fertiliser, apply as soon as possible. Have the fertiliser in the yard ready for spreading. If slurry was applied a minimum of 2 weeks ago, then the silage crop will utilise 2 units/acre of nitrogen per day from the date of fertiliser spreading to the anticipated harvest date. A nitrogen product such as YaraBela Nutri Booster or an NPK such as YaraMila Silage Booster would be ideal in this situation.

3. Nothing applied to date.

Be very careful applying slurry on first cuts at this late stage. Only apply if there are light grass covers (<2,250 kg DM/ha) and the slurry is dilute and is being applied by trailing shoe or dribble bar. Otherwise, delay slurry applications until after harvest because of the risk that residues from the slurry will persist on the grass up to harvest or that these residues are picked up off the soil surface at mowing/raking/picking up.

As for the nitrogen rate, calculate the number of days from when the nitrogen fertiliser is applied to the anticipated harvest date and then use the 2 units/acre of nitrogen per day rule. If slurry is being applied, account for the available nitrogen in the slurry when calculating how much nitrogen fertiliser is required. If slurry is not being applied, and soil P & K indices are index 2 or less then use an NPK fertiliser such as YaraMila Silage Booster.

Another option that some farmers might be considering for this scenario might be to cut in the next two to three weeks if field conditions allow and then focus on the second cut. If this is the strategy you choose, then only if good ground conditions exist at harvest to minimise soil contamination. This late April/early May mown grass is more likely to have lower sugar levels, so this would need to be considered at mowing. Achieving a good wilt and using a silage inoculant could help counteract sub-optimum sugar levels.


Can you identify grassland nutrient deficiencies?

Identify and diagnose if your grassland is suffering from nutrient deficiencies and learn more about the symptoms and causes and how to control or correct the deficiency

Nitrogen deficiency
Nitrogen deficiency





Phosphorus deficiency
Phosphorus deficiency





Potassium deficiency
Potassium deficiency





Sulphur deficiency
Sulphur deficiency





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