Apply with care and earn profits from N
ACCURATE and even spreading of nitrogen fertiliser at the right time is important to maximise profits and protect the environment.
That was the message from Kemiras George Mackenzie at a Fertilisers for Grassland conference in Exeter this week.
"Often fertiliser spreaders put the correct amount of N on the field, but in some areas applications may be 20% below and in others 20% above the required rate," he said.
Kemira trials show that on every acre where N is unevenly applied, silage yields may be cut by 0.8t/ha (0.32t/acre) for a 20% dry matter crop. When silage is valued at £16/t that amounts to £12.65/ha (£5.12/acre), said Mr Mackenzie.
"The simplest way to avoid yield losses is to have spreaders calibrated by the maker or an independent engineer, with a test tray. To spread accurately the machine must also be well maintained.
"Despite the cost of fertiliser and spreaders, all too often the spreader is left out until the day of spreading." But aiming to compensate for inaccurate spreading by increasing nitrogen rates should be avoided since the risk of run-off or leaching is high, he warned.
Mr Mackenzie advised using a quality fertiliser especially when the spreading width is 24m (80ft). In that case an SP5-rated product is needed. He also recommended applying nitrogen according to T-sum 200. For grazing all nitrogen can be applied at T-sum 200 and for grass silage half should be applied at T-sum 200 and half six weeks before cutting.