Grass growth: Have no fear; the rain is here

Rainfall amounts have been very varied across the country in the past seven days, but it is expected that many areas will receive above average amounts of rainfall this week.

This will be a welcome sight for some, as soil moisture deficits (SMDs) are still very high in parts of Munster and across much of Leinster – ranging between 35mm and 45mm in these areas.

Although according to Met Éireann, SMDs “will decrease this week with many areas close to saturation point by the end of the week away from the south east”.

Where SMDs are high, grass growth is still being affected. Relatively high growth rates have been experienced elsewhere.

Image source: Met Éireann

In terms of average grass growth rates, AgriNet figures are showing 68kg DM/ha in Ulster, 68kgDM/ha in Leinster, 61kg DM/ha in Connacht and 62kg DM/ha in Munster.

However, these are just averages and grass growth is as low as 36kg DM/ha in parts of Leinster.

Building grass

As we are now in the month of August farmers need to start thinking about building grass on the farm for the end of the grazing season and next spring.

The figures below are the Teagasc target average cover/cow, at a stocking rate of three cows/ha:
  • August 15 – 250kg DM/ha;
  • September 1 – 330kg DM/ha;
  • September 15 – 370kg DM/ha;
  • October 1 – 380kg DM/ha;
  • November 1 – 65% of your grazing platform should be closed at this stage.

A rotation length target of approximately 25 days should be maintained in the month of August. This should be increased to between 30 and 35 days from about mid-September onwards.

Another option is to reduce the demand on the farm. This can be done through selling off empty cows, cows which are performing poorly or removing any young stock from the platform.

Applying nitrogen (N) – while staying within your limits – along with continuing to reach target residuals of between 3.5cm and 4cm.

Introducing meal is the most expensive option when building covers, but it is usually necessary at a high-stocking rate. Alternatively, highly-stocked farms can introduce high-quality bales if surplus is available.