Silage 2024 - quality and quantity needed
Recent weather reinforces the need to have quality silage reserves. Do not delay first-cut silage in order to bulk up the crop and replenish diminished silage stock.
Delaying is likely to have a negative effect on silage quality, as well as reducing the total yield for the year. Delaying the first cut beyond late May is likely to result in lower total dry matter yield between the first and second cuts. Silage crops will lose one unit of DMD for every two days cutting is delayed after heading out. Harvest the crop at the right time to reset the grass plant and get it back producing digestible material.
Use the options available A concern this year will be allowing enough time for late applications of fertiliser N to be used up by the grass plant. The rule of thumb is that two units of N will be used on average every day; however, the only way to be sure of the N levels in the crop is to have a sample tested. Where adequate sugars are available, grass can be successfully ensiled with nitrate levels in excess of 600ppm. Discuss test results with your advisor and use options such as wilting the crop or using additives if needed.
Digestible yield is limited by changes to grass quality post heading.
Nitrogen fertiliser for grass and clover swards
In the summer, when sward clover content is sufficient (≥20%), nitrogen (N) fertiliser application can be reduced. Suggested N application strategies for grass-clover swards with a range of sward white clover content are outlined in the table below.
Nitrogen fertiliser application strategy for a dairy farm on a range of sward clover contents assessed in April.
| April average sward clover content1 | Feb | March | Apr | May (two rotations) | June (two rotations) | July (two rotations) | Aug | Sept | Total |
| kg N/ha | |||||||||
| Grass sward | 24 | 36 | 20 | 32 | 28 | 28 | 21 | 23 | 212 |
| 5%2 | 20 | 35 | 20 | 20 | 20 | 20 | 20 | 20 | 175 |
| 10%³ | 20 | 35 | 20 | 15 | 15 | 10 | 15 | 20 | 150 |
| 15%4 | 20 | 35 | 20 | 15 | 10 | SW6 | 10 | 20 | 130 |
| 20%5 | 20 | 35 | 20 | 15 | SW | SW | SW | 15 | 105 |
1. April average sward clover content (%) – clover content determined in April. 2. 5% clover content in April = 10% average annual sward clover content. 3. 10% clover content in April = 20% average annual sward clover content. 4. 15% clover content in April = 25% average annual sward clover content. 5. 20% clover content in April = 30% average annual sward clover content. 6. SW – soiled water – soiled water should be applied when chemical N fertiliser is not spread.
This article by Dr Joe Patton first appeared in the Teagasc Dairy Advisory newsletter for May. Read the full Teagasc Dairy Newsletter for May.