Teagasc has warned farmers not to spread fertiliser if grass growth drops below the critical threshold of 35kg DM/ha, as doing so could waste costly nutrients while putting water quality at risk.

The warning comes as PastureBase Ireland figures put much of the south, east and midlands down to witness sluggish grass growth rates for the coming week as the slow arrival of rainfall delays a return to more typical late summer grass growth rates.

Farmers have been advised by Teagasc’s Grass10 campaign to not spread fertiliser until one week to 10 days after receiving rain, as dry spells bring a release of soil nitrogen as a result of mineralisation.

Fertiliser application should, instead, wait until consistent growth rates in excess of 50kg DM/ha per day are seen, Teagasc said. It added that some farms, particularly those in the northwest, may continue to spread fertiliser as grass growth rates are tracking on par with previous years.

Huge variations in rainfall have been seen across the country in the week up to Tuesday.

While Athenry, Moorepark, and Ballyhaise all received more than 25mm of rain in the week up to Tuesday, Grange, Co Meath, Dungarvan, Co Waterford and Clonmel, Co Tipperary, all saw less than 20mm.

Minister for Agriculture Martin Heydon noted that Teagasc’s annual fodder survey is currently underway, with results expected by mid-August.

“As in previous years, the survey will assess fodder stocks ahead of the winter and will provide farmers and wider industry with an overview of the national and regional fodder situation,” he said. He said that the current year’s grass growth up to 21 July was just over 0.5t DM/ha ahead of the five-year average, but that reduced soil moisture was beginning to eat away at this lead.

Teagasc’s head of dairy knowledge transfer also signalled last week that the drought had hit at least 70% of the country’s dairy herd, either through restricted grass intakes or by farmers’ need to feed out silage and additional concentrates.