Now that the closed period is over… should I spread?

Just because the closed period has ended for all farmers in Zone A, and soon to end for other farmers, this doesn’t necessarily mean that this is the best time to spread nitrogen (N) fertiliser.

It is a well known that the lack of nitrogen (N) in the soil can limit spring-grass growth, but the timing and rate of fertiliser N application are key decisions that need to be taken into consideration by every livestock farmer.

Research, Teagasc says, has shown a large range in grass response to early N applications – between 5kg of DM and 18kg of DM/kg of N applied. 

While the appropriate application of early N is beneficial, Teagasc says the incorrect application of early N is wasteful, costly, pollutes water and increase greenhouse gas (GHG) emissions.

For these reasons, Teagasc have released some key ‘do’s’ and ‘don’ts’ to guide you in your decisions around early fertiliser application.

Teagasc have outlined the following ‘do’s’:
  • Check Teagasc guidelines on application of early N;
  • Check the weather forecast prior to making fertiliser N application decisions;
    • Check the soil moisture deficits (SMDs) for your area and only spread if SMD is greater than zero (check this on the Met Éireann website);
    • Only apply fertiliser N when soil temperature is greater than 5° and rising;
  • Target fields for early N that are most likely to respond to an early N application, such as:
    • Perennial ryegrass/recently reseeded paddocks;
    • Drier, free draining paddocks;
    • Paddocks with a cover of greater than 400kg of DM/ha or 5cm;
    • Paddocks with optimum soil fertility;
  • Replace chemical N fertiliser on approximately one third of the farm with cattle slurry. Target these applications to paddocks with low phosphorus (P), low potassium (K) levels and low grass covers;
  • Use protected urea (NBPT) for early N applications;
  • Apply up to 30kg of N/ha (24 units of N/ac) in first split in late January or early February and avoid fields that have received an application of cattle slurry;
  • Link your early N application strategy with spring feed budget for the farm;
  • Calibrate and maintain your fertiliser spreader in good condition.
Also Read: Slurry spreading season: When can you start?

Teagasc have also outlined the following ‘don’ts’:
  • Don’t apply fertiliser N before the end of the prohibited spreading period;
  • Never apply fertiliser on waterlogged or frozen soils;
  • Don’t apply fertiliser if a yellow rainfall warning is in place or is forecast within the next 48 hours;
  • Never apply fertiliser into buffer margins and know you buffer margins;
  • Delay N on bare fields (<400kg of DM/ha); instead spread on fields with 5cm (cover of 400kg DM/ha) grass cover or greater;
  • Don’t apply N fertiliser on fields that received slurry in the first round;
  • Don’t apply more than 30kg of N/ha (24 units of N/ac) in first split in late January/early February;
  • Don’t apply more than 90kg of N/ha (slurry N plus chemical N) in total up to April.

Teagasc have also advised farmers to follow, where weather is permitting, the N fertiliser application plan (see below) for the spring period.

Image source: Teagasc