After a cold, slow start in May, grass growth has finally taken off across the UK and Ireland, with most farmers reporting healthy growth on the back of some very welcome rainfall. But that growth has brought a much less welcome development: grass quality is starting to slip. Decisions taken now will determine performance in the paddock and in the clamp right through to autumn.

Philip Cosgrave, Yara's country grassland specialist, has been listening closely to farmers and closely studying the data too. "Grass seems to be growing well at the moment," he says. "Most farmers I've been talking to are happy enough with growth. We've had enough rain – maybe too much in places. But the issue now is grass quality, not quantity."

Grass quality is in decline

The concern, flagged by farmers and both AHDB's Forage for Knowledge project and the Grass10 programme in Ireland is that quality is deteriorating just as growth accelerates. "Later-heading varieties are running to seed, pre-grazing yields are climbing higher than is ideal and growth is outpacing demand on many grazing platforms. That's when quality can drop," Philip explains. 

The impact is significant. According to recent Forage for Knowledge analysis, a 0.75-unit drop in metabolisable energy in cattle eating around 17kg of grass dry matter, is equivalent to a loss of two litres of milk a day. Managing sward quality now has a direct bearing on milk yield and liveweight gain.

Philip's advice is to act early. "Taking out paddocks early increase stocking rates on the remaining paddocks and resets grazing height on those paddocks cut for silage," he says. "I'm not advocating pre-mowing as standard practice, but in some instances, it may be necessary to reset that post-grazing sward height. For some farmers it'll be topping."

Don't forget P, K and sulphur on grazing ground

This is also the point at which phosphate levels in grass naturally begin to fall, making it a sensible time to top up where soil analysis shows a requirement. "With paddocks coming out of the rotation for silage, replacing offtakes matters," says Philip. He suggests parlour washings are a useful low-level source of nitrogen, phosphate and potash on grazing paddocks, particularly where clover content is higher. "On white clover swards during the middle of summer, it's still worthwhile applying around 10 to 11kg/ha of nitrogen wafter every round of grazing, without impacting the clover," he suggests.

Clover swards need particular attention. "Clover is very sensitive to low P and K fertility," Philip notes. "Keeping up with P, K and sulphur applications will improve clover persistency and nitrogen fixation." 

Build contingency now for a dry spell later 

First and second cuts are now in across many areas, but Philip is hearing mixed reports on yield. "Farmers have been disappointed with first-cut yields, early or late," he says. "That's not surprising given the spring we've had but again steps can be taken now to improve later cuts."

Last year's drought is still being felt on many farms. Philip cites one example where the additional cost of bought-in forage, compared with the previous winter, came to almost £40,000. His advice is for farmers to review where they stand after first and second cuts and build in contingency for a dry spell later in summer or an early, wet move to housing in autumn.

That means making sure later cuts get the nutrition they need. "Nearly half the soil analysis results coming in across the UK and Ireland show suboptimal soil potash levels," Philip warns. "A tonne of grass dry matter removes somewhere between 25 and 30kg of K₂O. Work that up across a five-tonne first cut and you're looking at substantial offtake." 

Rather than defaulting to straight nitrogen and sulphur for later cuts, Philip recommends calculating what's already been applied and whether an NK sulphur product – such as YaraMila NK SULPHUR (or YaraMila ZERO P CUT in Ireland) is the better fit to balance offtakes.

Phosphate rules are tightening

Phosphate policy is under increasing scrutiny. In Northern Ireland, discussions are ongoing on the next Nutrients Action Programme (NAP), with stricter controls expected on both organic and inorganic phosphate sources. "This is leading to recommendations being reduced, or to more careful nutrient accounting being needed," Philip says. He recommends farmers assess phosphate use against a nutrient management plan to ensure compliance, rather than working without one.

Soil analysis has its limits too. "It's not guaranteed that what soil analysis shows is necessarily available," Philip cautions. "Other factors, like soil pH, come into play as well." 

Three priority actions for mid-season

Philip's key messages centre on three areas. Firstly, for grazing, reset sward quality – through earlier grazing, pre-mowing or taking out paddocks to lift stocking rate elsewhere. Second, review what's already been applied and act now: phosphate applied in August through a 27-5-5 product arrives too late for swards that need it now. Third, on silage ground, balance offtakes properly rather than defaulting to nitrogen and sulphur alone, particularly where potash is in deficit.

"It all sounds simple," Philip says, "but like everything else, it needs to be done properly, with attention to detail. But after a tough spring, it will really help to improve sward quality and grazing right the way through until autumn."