Now is not the time to skimp on fertiliser

The rapid rise in fertiliser price, particularly for fertiliser N, is causing some farmers especially those stocked at lower levels to question the economics of spreading Nitrogen this year. George Ramsbottom Dairy Specialist advises farmers to fertilise to maximise grass growth in April/ May

Teagasc issues guidance on application rates for fertiliser N throughout the year. Higher stocked farms are advised to apply greater quantities of fertiliser N on average than their lower stocked counterparts. The range in recommended fertiliser N application rates for grazing varies from 30-50 kg per hectare in the April and May period. The rapid rise in fertiliser price over the past number of months, particularly for fertiliser N, is causing some farmers especially those stocked at lower levels to question the economics of spreading Nitrogen this year.

Research from Teagasc Johnstown Castle has shown a recovery rate of between 80% and 100% of the Nitrogen applied in the April-May period (assuming adequate pH, P and K indexes). Recovery of fertiliser N increases with increasing soil temperatures which usually occur at this time of the year and coincides with the time of greatest grass growth rate as pasture moves from the vegetative to the reproductive phase of its life cycle.

The response in terms of plant dry matter and the Nitrogen costs per additional grass dry matter grown are presented in the following table following the application of one tonne of CAN.

• [1] Each kilo of plant protein contains 160 grammes of N. April May grass typically contains approximately 20% protein. 
• [2] A cost of €1,000 per tonne of CAN is assumed in this example.

This analysis shows that even at a cost of €1,000 per tonne, the response to fertiliser N achieved in April/May is economic relative to the cost of other feedstuffs available to feed livestock.

The message is to make the most of the opportunity of the rapid grass growth rates occurring at this time of the year. Capture the surpluses that arise in the form of silage for the winter ahead.

Read more here about Grassland and fertiliser

The Teagasc Dairy Specialists issue an article on a topic of interest to dairy farmers every Monday here on Teagasc Daily.