In this article, CAFRE dairy technologists, Robert Patterson and Aidan Cushnahan, discuss planning for first cut silage.
Reducing fertiliser applications below recommended levels may reduce costs in the short term but may also result in significant reductions in grass yields, which you will have to supplement with the purchase of more expensive alternatives.
With most farmers having applied slurry to their silage swards, thoughts now turn to fertiliser applications.
The increase in fertiliser price and concerns about product availability have caused many producers to question the most appropriate course of action.
You should take the following steps to optimise the use of this resource.
Fodder budget
Carry out a fodder budget to assess the amount of silage required for your herd.
You can use the figures we have quoted in table 1 to achieve this. Remember to allow 10 – 15 % extra for field and in silo losses.
Crop Nutrient Management Calculator
Use the DAERA Online Crop Nutrient Management Calculator to match the nitrogen (N) supply according to requirements for first cut silage (120 kg N/ ha).
This will allow you to:
- Accurately account for slurry you have already applied;
- Estimate how much additional N you require;
- Establish where is the need for extra phosphorus (P) and potassium (K).
Remember that you will obtain optimal grass growth responses to fertiliser N in the period leading to and around cutting grass for first cut silage.
Therefore, where possible, try to match the amount of fertiliser applied to crop requirements.
Remove non-productive livestock
Furthermore, remove all non-productive livestock from your herd as soon as possible.
Reduce the herd’s demand for silage by:
- Carrying out a critical review by identifying the livestock that are not contributing to your business;
- Removing them earlier rather than later.
For example, six ‘problem’ dairy cows can consume up to 50 t fresh silage over a six-month period.
Removing these animals now could be equally as beneficial to fodder supplies over the year as removing significantly more animals next winter.
Calibrating your spreader
Ensure your spinner is calibrated appropriately for the product you are applying. Also, consider the benefits of split applications when applying fertiliser for first cut silage, to minimise the risk of losses.
What impact could reducing fertiliser inputs have?
If you are planning to reduce fertiliser inputs for first-cut silage, it is important to note that any savings in fertiliser may be offset by later having to source more expensive alternatives to address potential reductions in grass dry matter (DM) yield.
For example, in a recent scenario generated for a 100-dairy herd plus followers at a stocking rate of 2.0 CE/ ha, it was estimated that reducing applications of CAN by 20 kg N/ ha per cut over a 3-cut silage system could reduce the amount of fertiliser applied by 7.4 t leading to a saving of around £6,500.
However, the reduction in yield may result in a reduction of around 200 t silage (60 t DM) to the resulting fodder stocks on the farm than in previous years.
Replacing this with purchased silage at £40/ t could result in a cost of £8,000.
Alternatively, replacing the deficit with concentrates at £400/ t could cost around £27,000.
The impact of this scenario will vary according to a range of factors, including:
- Stocking rate;
- The productivity of your silage swards;
- Cost of alternatives;
- Existing stocks of silage on your farm.
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