Growers need to understand how plants respond to nitrogen (N) when reducing rates due to high prices this season, according to Teagasc’s Dr Richie Hackett.

Hackett said that the biggest yield responses to applied N come from the lower doses.

Based on winter cereal research, he said that the first 50% of an N application typically gives 70% of a crop’s yield response.

He suggested that N rate reductions could range between 27kg and 35kg N/ha for winter barley and wheat crops, around 16%.

This could result in average yield losses of between 0.2t/ha and 0.3t/ha.

This figure is based on a crops break even ratio (BER), which is calculated by dividing the cost per kilo of N by the price per kilo of grain.

In turn, this is used to calculate the optimum rate of N, which will determine how much growers can reduce rates by.