National Dairy Conference Questions Answered: Spring Nitrogen recommendations

Teagasc Dairy Specialists and farmer speakers answer questions from the National Dairy Conference, which were unanswered on the day, due to the volume of questions asked, here on Teagasc Daily this week. Today's question is on Spring Nitrogen recommendations answered by Michael O’Donovan, Moorepark

With the recent increases in fertiliser cost many questions were asked at the Dairy Conference about Teagasc’s recommendations on early Nitrogen. 

According to Michael O’Donovan, Teagasc Moorepark, ‘Lack of nitrogen (N) supply in the soil can limit spring grass growth. Research has shown a large range in grass response to early N. The range can be between 5 to 18 kg DM/kg N applied. While the appropriate application of early N is beneficial, the incorrect application of early N is wasteful, costly, pollutes water and increases greenhouse gas emissions’. His recommendations included applying fertiliser N (ideally protected urea) where soil temperature is greater than 5°C and rising on fields with good soil trafficability. No more than 29 kg N/ha (23 units N/ac) chemical N fertiliser should be applied in February. Fields most likely to respond to an early N application will have a high perennial ryegrass content, a cover of greater than 400 kg DM/ha with optimum soil fertility, i.e. good P and K status, pH > 6.2.

Making best of use of slurry means getting more area covered at moderate rates in spring and targeting the slurry to high demand areas e.g. silage ground and low P and K grazing ground. He believes that farmers should apply cattle slurry instead of chemical N fertiliser on approx. 50-60% of the whole farm area in spring using LESS (low emissions slurry spreading) techniques.

Michael suggested that farmers spread slurry applications to fields with low P and K levels and low grass covers (<1,000 kg DM/ha) at rates of no more than 25 m³/ha (2,500 gals/ac) to supply ~25 kg/ha (20 units/ac) of available N.

See more on the Virtual Dairy Conference 2021 here.

The complete Dairy Conference Proceedings can be viewed here and the individual articles were published on Teagasc Daily throughout last week. See Teagasc Daily - Dairy for more.