Grass grows 15kg/ha for every unit of Nitrogen applied in March – Teagasc

The average growth response from Nitrogen (N) applications in March is 15kg/ha every unit of N applied, according to Teagasc’s Brian McCarthy.

The Moorepark-based Research Officer spoke at a recent farm walk attended by over 50 farmers on James Kennedy’s farm in Nenagh, Co. Tipperary.

McCarthy said that N applications are critical to grow grass this spring, as growth rates on many farms have been lower than normal, due to the cold and wet weather over the past couple of months.

“The response to Nitrogen is higher in March than February due to the higher ground temperatures,” he said.

Soils definitely need a Nitrogen boost this spring.

McCarthy also cited research which shows that urea is the most effective fertiliser to use during the spring time, as it is less likely to be lost through leaching.

“Urea is the fertiliser to go with over Calcium Ammonium Nitrate (CAN) or a compound fertiliser such fertiliser such as 18:6:12,” he said.

However, for fields that are lacking in Phosphorous (P) and Potassium (K), compound fertilisers can be used to address the nutrient deficit, he said.

He said that farmers can apply 2 bags of 18:6:12 to address this issue, but they must be aware that the N component of compound fertilisers is CAN, which can be prone to leaching during wet weather.

“My advice would be to stick with the urea in March and then go with the compound fertilisers in April,” he said.

On farms where very little or N has been spread to date, McCarthy recommended that they spread at least 40 units of N per hectare.

He said that this application is necessary as high rainfall levels over the past couple of months have washed N out of the soil.

Farmers should spread any grazed fields with slurry as soon as possible, he said.

The efficiency of slurry is also six times greater in than spring than the summer due to the lower temperatures.