The Grass Week: make the most of rising growth rates

The average growth rate recorded on Pasture Base Ireland (PBI) over the last seven days was 61kg DM/ha. This is up from 45kg DM/ha the previous week.

This increase in growth is expected to continue as most areas have got rain at this stage.

Predicted growth rates as we head into the weekend range from the mid-60s to the mid-80s across the country.

During our Irish Farmers Journal grassland management courses this week, we started to look at building covers for autumn grazing.

Extra days

Each extra day at grass is worth around €1.80 per cow, which is €180 per day for a herd of 100 cows.

While soil type and weather conditions have a big bearing on how long cows and cattle will be able to stay grazing, grass availability is something we can control.

The targets for autumn grass a dependent on stocking rate (SR). By mid-August (this weekend), the target average farm cover (AFC) and cover per livestock unit (C/LU) are:

Rotation length should also be extended to 25 days at this stage.

In the groups this week, grass availability was very variable. This was mostly down to rainfall over the last month.

Growth rates ranged from 44kg DM/ha to 83kg DM/ha between this week’s groups. This has also meant there are two very different situations on farms.

Grass deficit

Farms that have only recently got adequate levels of rain may be behind target. Low growth rates have resulted in falling AFC and C/LU.

Once growth starts to improve, the only option is to pull up the handbrake by increasing supplementation in the form of concentrates and/or good-quality silage.

Ensure fertiliser applications are up to date and make the most out of the good response to nitrogen in mid-August.

Monitor growth weekly and make informed decisions if reducing supplementation in the coming weeks.

Grass surplus

Where there is a surplus of grass on farm, now is the time to take out surplus bales.

Target cutting paddocks with poor-quality grass to ensure good-quality grass is available for the next rotation.

Building covers too early will result in very high pre-grazing covers in mid- to late-September.

Covers above 2,400kg DM/ha are very difficult to graze out correctly, especially when weather conditions in late September can be wet.

Poor graze-outs in the last couple of rounds will affect grass growth over the winter months and will also have an effect on grass quality in spring.