Mark Means’ aim this spring is to ensure that soils in his sugar beet and potato fields don’t exceed 1 megapascal (MPa) on the penetrometer during establishment.

While he has already made progress in improving the health of his silt soils, the 2024 Arable Farmer of the Year wants to go further after seeing research showing how critical early rooting is to crop performance.

“The yield potential of potato plants is set in their first 8-9 weeks of growth, and this is largely driven by root growth and seed and soil nutrition,” he says. For high yields there is therefore a need to maximise root growth.

See also: How new technology enables yield mapping for root crops

Current approach

One factor that can restrict root growth is soil compaction, and the silt-rich soils that Mark crops at Terrington Marsh in north Norfolk are prone to this.

This was highlighted in the wet autumn of 2012, where he recalls the impact of sprayer wheelings and lifting potatoes was a maximum 50% of field yield.

He has already developed a reduced cultivation approach to establish potatoes, which consists of ploughing in the autumn and leaving it overwinter.

Then in spring, he runs a shallow drag though and then plants directly into the soil after a rotary cultivator – only cultivating to a depth of 15-20cm. He doesn’t need to use a destoner.

Potato crops are also grown within a controlled traffic farming system with 36m permanent tramlines for spraying and fertiliser. Turkey muck is used to add organic matter and improve resilience.

Soils have become healthier – organic matters are getting close to 4% and there’s little compaction in potato wheelings. Doing as little cultivation as possible has also cut fuel use by 11 litres/ha.

However, since soils are likely to be close to their plastic limit for cultivation during early spring, Mark says there still exists the potential for soil compaction to occur during planting, which will restrict root growth.

Therefore, he believes if he can achieve better rooting, plants will harvest more water, reducing the need for irrigation and scavenging more nutrients from the soil.

Soil penetrometer

Looking at the AHDB archives, Mark points to cultivations research carried out by Mark Stalham for BPC, when he was at the Cambridge University Farm.

The research looked at soil resistance to rooting. With soils reading less than 1MPa on the penetrometer, growth rates were unhindered.

But at 1.5MPa, root grow rates were halved, and at 2.4MPa, growth was only one quarter the unhindered rate.

But what is concerning is that a survey of 602 fields over the period 1992-2004 showed two-thirds were at 3MPa or higher in the potential rooting zone.

“This suggests in many fields, rooting is hindered after planting,” he says.

Less rooting will lead to reduced water and nutrient uptake. “Slower root growth also means slower canopy growth and later emergence.”

Therefore, Mark will monitor the impact of drilling sugar beet and planting potatoes on soils with the help of three new penetrometers.

He has spent the past few weeks taking baseline measurements of overwintered, ploughed fields.

Currently they are measuring less than 1MPa at field capacity and the key aim is to keep it that way during establishment.

Reducing tyre pressures is one way to cut the risk, and the soil conditions at the time of Farmers Weekly’s visit is a good example.

Mark explains that soils have dried on the surface, but are still wet at depth. He describes the soil as being like a chocolate brownie – dry on the outside while moist and sticky inside.

Reducing tyre pressures means the crust can take the weight of the tractor and machinery by spreading the load. Otherwise, it would squish and compact the wetter soil further down.

Last year, Mark invested in a TractAir auto inflation system with help from a Farming Equipment and Technology Fund (FETF) grant.

The system makes changing pressures more practical, as the driver can reduce the pressure in the field and then reinflate tyres to 17.4-20.3psi (1.2-1.4 bar) via isobus from the cab, for safe travelling on roads.

The auto inflation system on the Fendt 724 © Mark Means

Tyre pressures

The aim is to get tyres down to 9psi and Mark has been weighing his tractors and kit to see if the tyres will allow this. 

Very High-Flexion (VF) tyres are built to enable tractors to carry out work like drilling at lower pressures. However, going too low can cause the tyres to heat when flexing and start to break down.

Running at 9psi is possible when drilling beet at 6-8kph with the Fendt 724. The 8t tractor has 900 R42 tyres on the back and 710s on the front. 

However, some operations need more horsepower and the next size up is the Fendt 728, which weighs 9.3t.

Again, according to the tyre manufacturer, they can run safely at 9psi in the field. But Mark explains that the 280-300hp limits the forward speed.

“With a 6m Vaderstad drill or potato cultivator, it will be slower and you can end up tightening soil with pounding by the cultivator. If you can get the speed up a bit, it will reduce the downward pressure on soil.”

The Fendt 942 has that power (380-410hp), but weighs 13t, and Mark is working with tyre manufacturers to find a solution.

“This is the challenge,” he says. “We need a 10t tractor with 340-350hp – or looking at it another way, 30kg/hp.”

But he is determined to achieve this, spurred by his experience last year with the Fendt 724 and the central inflation system. “It has made a tremendous difference to emergence and uniformity.”