Building autumn grass on beef farms

It’s been an almost textbook summer on a lot of beef farms around the country in terms of grass growth and grassland management.

Early indications from the first of the BEEP weighings around the country suggest calf weight gain on suckler farms has been very good. Weight gain and animal performance has also been very good on finishing farms, with cattle coming fit quicker than usual.

While spring 2022 may seem a long time away, what happens on beef farms in the next six weeks will determine the turnout date next year.

The naysayers will point to the big snow of 2010 that decimated covers and say closing off grass early is a false economy.

While there is a risk of this, the benefits of trying it will far outweigh the negatives. We know that come next March it will cost over €2/day to feed a 350kg weanling inside while feed costs will come in at less than €1/day if that animal is grazing spring grass. We are facing into a winter of high feed costs so reducing the length of the indoor feeding period was never more important on beef farms.

The focus of autumn grazing management is to increase the number of days at grass and animal performance, but also to set the farm up during the final rotation to grow grass over winter and provide grass the next spring. There are two key autumn periods:

Generally, rotation length should be extended from 10 August. The focus of this period is to gradually build pre-grazing herbage mass, targeting covers of 2,000kg to 2,300kg DM/ha in mid-September.

Removing paddocks after the first week of September should be avoided if possible. A September harvest is too late as paddocks do not have enough time to re-grow to make any meaningful contribution in the last rotation. By achieving the right farm cover at the right time, decisions are easier to make. Many farmers fall into the trap of building cover too late and are pushed into harvesting excess grass in September.

On beef farms, grazing stocking rates are varied but generally low, which has a huge effect on feed demand. As the deadline date for chemical nitrogen application is 15 September, farmers must decide in late August/early September what level of N they will apply to ensure sufficient grass growth for the final rotations.

Farmers with a high grass demand in October/November, who have their N applications up to date by August, should consider a blanket application before the 15 September closing date.

The amount to apply may vary, and will depend on feed supply. Only blanket spread N if the farm is under target for grass. Spreading excess N in autumn is a waste of money as the soil is naturally releasing nitrogen.

Soil temperatures stay quite high in September and grass responses per kg N of between 10kg to 15kg DM/ha have been recorded under good growing conditions.

Swards with more perennial ryegrass will respond better to nitrogen and these should be targeted for building autumn grass. Swards on a long rotation with nitrogen applied have the capacity to achieve grass growth rates of up to 40 to 50kg DM/ha/day through September and October.

Autumn slurry

Timing of slurry application has little effect on P and K utilisation from slurry, provided application does not take place in periods of heavy rainfall that might cause significant run-off losses. Timing of application only has an effect on N availability due to ammonia volatilisation in warmer and drier weather. About 85% of the economic fertiliser value of slurry is due to its P and K content; 70% is K (about five units of P and 38 units of K per 1,000 gallons). Since application in autumn has little effect on P and K utilisation, most of the slurry value will still be utilised with autumn application.

Tullamore Farm is ahead of target at the moment in terms of grass supply and average farm cover.

Very strong growth of over 60kg/DM/ha/day over the last number of weeks has meant grass covers have been building well. The last fertiliser went out on 19 August with one bag of pasture sward/acre spread across 65 acres. The final application will be spread at the end of this week, with about 40 acres getting another bag/acre of pasture sward.

Average farm cover is currently standing at 1,130kg/DM/ha with an average growth figure of 72kg/DM/Ha for the last week.

With current demand at 31kg/DM/ha you might question the fertiliser application but the farm will have a big demand for grass coming up to breeding time for the ewe flock in October.

The farm currently has 36 days of grass ahead of stock. The plan is to start closing up paddocks for early grazing from 1 October with a target of 60% closed by the first week in November.

Cattle will be housed first with sheep grazing off paddocks until early January 2022.