Crack compaction to get more milk from grass

Autumn will be a key time for the Dugdale family, as they look to increase milk from grazed grass with their 400-cow herd of autumn calvers.

The coming weeks are also crucial for tackling severe compaction, which is preventing them from making full use of their grazing.

The herd of New Zealand cross-bred cows at Crathrone Farms, North Yorkshire, produces 2,800 litres from forage with a total yield of 6,800 litres with 4.6% fat and 3.6% protein.

Their target is to increase it to 4,000 litres from forage, mainly through better use of grazed grass in the shoulders of the season.

In previous years, cows were turned out in mid- to late-April, but this year they were out on 8 March with a farm cover of 2,048kg DM/ha, each cow initially consuming about 4kg DM/day of grazed grass. They were fully out by 14 April.

Top tips for aerating swards

These techniques are potentially very destructive to the grass sward so it is important that they are only used where soil compaction has been identified, and preferentially in the autumn to give the soil and the sward time to recover.

  • Assess the soil to ensure the correct machinery is selected to work at the correct working depth. Working at 1-2cm below the depth of compaction is advisable.
  • Slit aeration is more likely to address near-surface compaction (0-10cm) while sward lifters offer the chance to address deeper topsoil compaction (<30cm).
  • Soil conditions at the time of aeration are key – too dry and the soil will shatter, too wet and smear of the soil is likely. Soil conditions are particularly important on heavier clays.

“We managed to cut concentrate use by about 90t, compared with last year and it is quite a saving given the cost of £290/t,” says Joe Dugdale, who farms with his father David near Yarm.

When grazing full time, cows don’t receive any concentrate, as Mr Dugdale looks to avoid reducing grazed grass intakes by feeding extra DM.

Grass growth has been good this season, peaking at 120kg DM/ha a day, but has recently slowed to 40kg DM/ha a day.

At the other end of the season, he is looking to maximise milk from grass with the newly calved cows on the autumn grass flush.

“Historically, we balanced concentrates and forage with grazed grass and we now have turned this on its head, so grass will be topped up with forage plus concentrates.”

To increase grass, Mr Dugdale has begun to focus on his soil, which is particularly susceptible to compaction. While rainfall is not excessive at 700mm/year, the farm is on heavy-medium clay soil, which brings its own challenges.

“You don’t want to turn out in March to mess up the pasture and affect subsequent grass growth.”

By correcting soil problems, he hopes not only to increase grass production, but also have better ground conditions for grazing in early season.

DairyCo extension officer Tony Hoile says that test pits revealed a severe compaction problem.

So last autumn Mr Dugdale trialled sward lifters going 0.25m deep 0.5m apart to break the compaction.

“The aim is to get air in the soil to stimulate deeper rooting,” explains Mr Hoile.

“The problem is that rooting is restricted to the top 5cm and any fertiliser that goes on sits in top 5cm. The shallow rooting also means grass droughts easily,” adds Mr Dugdale.

But it didn’t do the job he wanted it to do. “It was too wet so, rather than lift and shatter the soil, it smeared.”

Therefore, this autumn, he is using a more extreme method of introducing 18ha of arable in his grazing platform. The 900ha farm includes 607ha of arable cropping.

He plans to spray off one-tenth of the grazing area with glyphosate and break up the compaction with a Sumo Trio subsoiler. “We will grow a crop of wheat and then put it back to grass.

“You just have to look at the lengths arable farmers go to get rid of compaction each year cultivating fields. But on grass, you can have as many as eight machines in a field at any one time when taking a silage cut and we then expect grass to leap back and grow again.

“Research shows that grass is the crop most affected by compaction, so it is a real issue,” he says.

Longer term, he believes some sort of tramline system as used on arable farms is the way ahead. Danish farmers are using controlled traffic farming, where all tractor traffic is restricted to 12m permanent traffic lanes.

“They are seeing big increases in grass yields,” he says. But he recognises that logistically it is difficult to achieve – even on the arable side – as you have to match up machine widths and tyre widths.

And it would also rely on contractors investing in the technology.

“I would like to see research carried out using tramlines or headland tramlines to restrict traffic to get some of the benefit as seen in Denmark.”

Mr Hoile adds that using GPS to reduce mower overlaps could also help.

While it is still a work in progress at Crathrone Farms, the benefits of improving soil structure have been proven. Tackling a similar compaction problem on another demo farm in Cheshire resulted in 3-13% increases in grass yield over two years.

DairyCo demo farms

The DairyCo-BGS Demo Farms project is part of the DairyCo Grassland, Forage and Soils Research Partnership.

This is a five-year collaboration with SRUC (Scotland’s Rural College), Harper Adams University and the University of Reading.

The aim of the demonstration farm project is to bridge the gap between research and farmers, putting the findings into practice on commercial farms.

Soil compaction is the focus at Crathrone Farms, mirroring a three-year research project being undertaken at Harper Adams University and SRUC.

Now in its third year, the project is addressing three key questions:

  • How does compaction impact on sward performance?
  • How does compaction from tractors or animals differ?
  • How effective are alleviation techniques?

There are four further demo farms looking at other topics including growing and feeding lucerne, using nutrients from slurry, and outwintering.

Details of open days can be found at

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