Get spreading now if planning March turn-out
By Emma Penny
FERTILISER should be applied now, regardless of T-sum, for those producers in the west of the country planning to turn-out cows in mid to late March.
Willie Murphy, grassland expert with Irish advisory service Teagasc, says that waiting until T-sum 200 is reached is often too late in the west of the UK.
"In the west, growing conditions are unpredictable. T-sum presupposes that theres no growth until 200 is reached, but in milder areas theres often potential for about 200kg/ha dry matter grass growth in spells of mild weather.
"Id recommend producers apply nitrogen as early as they can on dense swards. There is a danger of run-off, which is a greater risk than leaching, so Id avoid applying fertiliser within 48 hours of rain – its a waste of time and money."
Some producers may be concerned that T-sum 200 has not yet been reached in their area, but T-sum is a guide rather than a definite deadline, says ADAS fertiliser specialist Peter Dampney.
"Theres a three-week window for applying fertiliser, which T-sum 200 usually falls into. As long as its mid-February onwards there should be little problem applying fertiliser before T-sum 200."
Wilts-based Genus consultant Neil Adams agrees that producers turning out early should aim to apply nitrogen by late February. "About 50 units/acre of urea, ideally, or ammonium nitrate, would be appropriate where mid to late March turnout is the target."
But when it is too wet, or on light, sandy, leaching-prone soil, Mr Dampney suggests waiting.
"The dry autumn and winter means theres likely to be higher than average levels of residual available soil nitrogen, more than enough to cover the demand of 10-20kg N/ha until March. Producers who cant get on the land shouldnt panic. There should be enough N in the soil to keep grass growing in the meantime."
In cooler, more upland areas, which tend to be wetter, with slower grass growth, application should be delayed until early March when T-sum 200 will be reached, he says.
And IGER Bronydd Mawr scientist Arthur Davies says that producers should wait even longer. He suggests waiting until soil temperature has reached 5.5C (41.9F) for five to seven days.
"Then at least you know the grass is growing – any earlier and theres little response. On average, T-sum 200 is reached 33 days before soil temperature reaches 5.5C here in mid-Wales."
• Apply now for early turnout in west.
• Apply about 60kg/ha fertiliser.
• In uplands, wait until March.