15 June 2025

Summer Grassland Management

Vincent Ronayne, Drystock Adviser with Teagasc Claremorris, shares key advice on managing grassland and silage after a dry spring, focusing on grazing, fertiliser use, silage planning, and weed control for summer 2025.

Following the recent extended dry spell from early March to the last week of May, the grassland management plan for grass and silage stocks may need to be reassessed on many farms.

The fine weather facilitated the earlier-than-usual release of cattle from sheds here in the west. Additionally, the mild conditions improved mid-season lamb performance on most sheep farms. With good-quality grass and warm temperatures, stock have thrived over the past eight weeks. However, the prolonged dry period negatively affected grass growth in late May and early June, particularly on drier fields. While recent rainfall has helped, higher-stocked farms must now address this reduced growth to prevent a shortage of grass through the summer. Grasses appear to have headed out earlier than normal this year, and fields that are not usually topped until mid to late June would now benefit from topping post-grazing to encourage continued vegetative growth into the month.

Phosphorus (P) and Potash (K) requirements should have already been applied. A top-up of Nitrogen (N), combined with the current mild rainfall, will support grass growth. At this point, due to fertiliser regulations and costs, all farms should have recently taken soil samples in order to make informed decisions on the nutrient levels required for each field. Any slurry remaining in tanks should be applied to harvested silage ground as early as possible to maximise its nutrient value, as much of the Nitrogen content is lost as the year progresses.

Lime is often overlooked on many farms, yet it is possibly the most cost-effective long-term fertiliser available. For example, where land requires 2 tonnes of lime per acre, the resulting loss in nutrient availability can be equivalent to around 33% of fertiliser used. That means one bag out of every three is effectively wasted. A simple calculation shows that with a 50 kg bag of 18-6-12 fertiliser costing €25 and lime at €35 per tonne spread (lasting 4–5 years), the potential savings are clear.

This year, due to the dry spell, many farmers made silage earlier than usual in mid-May. These farmers would typically cut in early June, and so the yield in bales per acre is lower than in previous years. The main advantage of this early-cut silage is its likely high quality and excellent feed value. However, the lower yield will require an additional cut, which may not have been initially planned. It is essential to calculate requirements to ensure that enough bales are made to carry stock through the winter and account for the possibility of a difficult spring in 2026. For those who have already completed their first cut and need to make up a shortfall, it is important to fertilise promptly to allow for a second cut by late July.

Finally, a note on weed control in grassland. Docks and thistles have become particularly prevalent on many farms this year. To maintain productivity, these weeds must be managed. Topping can help keep them under control but will not eradicate them. When spraying or using lick treatments, it is vital to follow the manufacturer’s instructions, especially with dilution and application rates. A common misconception is that using more spray than recommended leads to a better kill. This is not true. Chemical companies invest millions in developing products that work optimally at specific rates. Applying too much can cause the leaves to die off quickly, allowing the roots to survive and regrow. The best approach is to always follow the manufacturer’s guidelines.