After a devastating year of extreme weather, from ‘Beast from the East’ to ongoing heatwaves, farmers’ silage stocks are sadly depleted. Whilst we can’t control the weather, we can respond by optimising spring nutrition to take control of spring grass growth so maximising silage yields and helping replenish dwindling reserves.
By focusing on early spring nutrition, you’ll have twice the benefit:
As soon as your soil is at 5°C and increasing, you should be applying nitrogen.
Specifically, for silage, you should be applying your fertiliser six or seven weeks before your expected harvest date. Any delay will greatly reduce your grass growth rates; it’s simply not wise to wait.
Grass response to nitrogen is highest in April and May, therefore the economic return on nitrogen is greatest on 1st cuts.
For grazing, spring will deliver a gradual increase in dry matter production per day. But there needs to be a readily available source of nitrogen to achieve this. Once soil temperature is at 5°C (often in February) the best approach to secure a continued availability of nitrogen is to put on small applications throughout the growing season.
According to our trials work, the optimum nitrogen rate is 120-130kg/ha for 1st cuts.
Using this rate of application and timing it accurately you’re likely to see a healthy six tons of dry matter per hectare.
Nitrogen is important for driving growth but without phosphate, potash and sulphur you will not get the best response from nitrogen and will loose yield.
Phosphate availability in spring limits growth
Phosphate is a key nutrient for spring grass, and its role in energy supply, root growth and tillering makes its availability crucial for grass growth in the spring. The plants requirement for phosphate is small when compared to nitrogen but its availability is essential.
Phosphate availability is reduced at low temperatures in spring but grass uptake in April and May can reach 0.25 kg P per day. At this rate of uptake the release of phosphate from the soil reserve is not sufficient, therefore mineral phosphate is necessary to top-up soil available phosphate to maximise yield and herbage phosphate concentration.
Sulphur and nitrogen should always be applied together
Recently we have been seeing significant responses to sulphur, particularly on intensive silage swards. Sulphur is needed for the applied nitrogen to be converted into grass protein which has the double impact of improving dry matter yield and reducing nitrogen losses to the environment.
The only sure way to avoid sulphur limiting nitrogen response is to apply both nutrients at the same time. Typically the yield response to sulphur will be about 10% although on lighter soils with low organic matter this can be nearer 20%.
Potash offtake by silage crops must be replaced
Potash should not be forgotten either, potash offtake at 25%DM is 6kg/tonne fresh grass, so a 20t/ha (8t/acre) crop will remove 120kg/ha (96 units/acre) and this must be replaced.
The following YaraMila compound fertilisers all contain combinations of nitrogen, phosphate, potash and sulphur (NPK+S) in appropriate ratios to maximise spring grass growth.
Yara supply our branded fertilisers and crop nutrition products to the Irish market through a network of local merchants and co-ops Use our interactive map to locate your nearest suppliers.