Due to the increased cost of chemical fertiliser in 2022, Teagasc has altered the recommended fertiliser application for silage fields.
Mark Plunkett, a tillage specialist with Teagasc speaking on the Precise Application of Fertilisers webinar and a recent Teagasc podcast, said that the recommended application rates of fertiliser from Teagasc have changed.
In previous years, Teagasc had recommended an application of 125kg nitrogen (N)/ha to obtain yields of 5t of dry matter (DM)/ha, but that has been altered this year to a rate of 100kg N/ha.
Noting that due to the increased cost of fertiliser in 2022, the extra 20kg N/ha does not pay.
Mark Plunkett recommended that farmers, when planning their application for silage ground, should use:
- 100kg N/ha or 80 units/ac;
- 20kg phosphorus (P)/ha or 16 units/ac;
- 125kg/ha or 100 units/ac of potassium (K), to total 90kg prior to cutting and 35kg after silage has been cut;
- 20kg of sulphur (S)/ha or 16 units/ac.
Fertiliser application
Mark stated that slurry will play a key role on farms this year as a fertiliser and that if used correctly, could account for up to one-third of your fertiliser requirement for silage.
Using a 6% DM slurry at a rate of 3,000 gallon/ac will make up nearly all the P and K requirements and a third, or 30kg of the N requirements.
Meaning urea, or protected urea and S can then be used for the remaining N requirements of 70kg/ha.
Mark recommended that the slurry is spread at closing and that the urea or protected urea and S is spread about a week later.
Where slurry is not available, Mark suggested that farmers use a chemical fertiliser such as 10-5-25 at a rate of three, to three and half bags to ac.
This will supply all the P and K for the crop at closing. A week later the crop needs to be topped with N. This can be the same form of urea or protected urea and S.