Spring N is essential to boost grass growth

To get the best response to nitrogen (N) in spring, the soil temperature needs to be 5°C and rising (at 10cm depth). Pay particular attention to the weather forecast, soil conditions and grass cover in the paddock, prior to applying N fertiliser.

Do not apply fertiliser if heavy rain is forecast or if rain is forecast within the next 48 hours. Be aware that you need to maintain a 2-metre buffer zone (no fertiliser N applied) from any watercourse.

According to Teagasc, the rate of fertiliser will depend on the farm’s stocking rate and demand for grass. The target for an intensive dairy farm is to have 70 units N/ac applied by April 1, if weather and soil conditions allow.

This can be achieved with chemical fertiliser, or a combination of chemical fertiliser and slurry. This is generally broken down into 23 units N/ac in late January to February, followed by 46 units of N/ac around the first week of March.

Slurry should replace chemical N on a portion of the farm’s paddocks.

Splash plate slurry spreading will supply six units N/1,000gallons. Using low emission slurry spreading (LESS) will increase N content. Trailing shoe or dribble-bar slurry spreading will bring about an increase of nine units N/1,000gallons.

LESS slurry spreading makes better value of the N. Spreading 2,500 gallons/ac of LESS slurry will contribute 23 units N. This is the same type of N as chemical fertiliser.

23 units N/ac is sufficient N for the level of grass grown from mid-January to March 1 (to help reduce the usage of chemical N on your farm, use LESS).

The remaining 46 units N/ac can be applied as chemical fertiliser to achieve the 70 units N/ac by April 1. Aim to use protected urea because it is less prone to water losses than CAN.

If there is a need for phosphorus (P) or potassium (K) on your farm, apply compounds like 18-6-12 from mid to late March, when soil temperatures are greater than 10°C.