Grass quality is vitally important on a dairy farm to maintain production and milk quality, while also reducing production costs.

During the panel discussion on day two of the National Dairy Conference over the past week, the issue of fertiliser prices was highlighted.

A question was put to the panel regarding reduced chemical nitrogen (N) fertiliser usage and sward quality. With such high fertiliser prices expected in the spring many farmers are looking for options to reduce their use of chemical N.

Clover is an option but takes at least 12 months to become established and slurry is another, which will be important but won’t replace chemical N fully.

Grass quality

Brian McCarthy, a Teagasc researcher based in Moorepark and Clonakilty in Co. Cork commented on sward quality from the clover trial at Clonakilty.

The trial has been looking at grass and grass clover swards production with different rates of N.

With the trial having four separate areas of study: Grass only low N (150 units), grass only, high N (250 units), grass clover, low N (150 units), and grass clover, high N (250 units).

The swards receive the same amount of N until June, when half the rate is applied to the low N areas.

Commenting on grass quality of low N grass only swards, Brian stated: “There are some preliminary results back, which showed no difference is grass quality of low N swards compared to high N swards.

“The organic matter digestibility and NDF were the same; the protein was only recorded in 2019 and it was the same.

“Now that could change over time, but those results are currently not available.”

Word of caution

Although grass quality is not impacted by the reduced N rates, yield will be reduced. So farmers that may be considering using lower N rates on grass only swards must keep that in mind.

Brian noted during the trial that the grass only low N swards, had a reduced amount of bales taken from the platform and silage was required to build covers in the autumn.

This increased the winter forage requirements on a farm that had a reduced amount of winter forage harvested.

This may lead to increased amounts of purchased feed being bought in, thus increased production costs.