After four decades of direct-drilling, Surrey grower Roger Colebrook has finally found the ideal machine to handle his wide-ranging soil types and varied cropping regime. Nick Fone reports.

After 40 years of direct drilling you’d think that you’d know all there is to know about no-till crop establishment. Far from it, according to Surrey grower Roger Colebrook who believes he’s still got plenty to learn about soil and crop management under an almost tillage-free regime.

“It might sound obvious but direct drilling is all about the soil. The problem is that no two fields are the same and on our land we’ve got every possible soil type from red clays with flint to greensand and gravel.

“That makes it pretty challenging to find the right tools for the job. After four decades I think we’re getting closer to finding the ideal combination of equipment – all centered around our new Sky EasyDrill.”

The six-metre seeder arrived at Chaldon Court last spring and has since sowed 1000 hectares of cash, cover, and forage crops for the business’s livestock and arable enterprises.

Its purchase was prompted by a number of factors led by a necessity for a much tighter drilling window.

“With a loss of metaldehyde, and our target to reduce our use of insecticides and herbicides, we now need to get all our autumn cereals sown in a five or six day slot around the second week in October. With contract drilling that can amount to over 400ha,” says Roger.

“Although our 15-year-old Amazone Primera is beginning to show its age it’s not ready for full retirement yet. With it moving to a back-up role we can have two 6m drills running and comfortably cover the ground.

“With its tine-type coulters and the Sky’s disc openers we’ve got the versatility to cover a range of conditions.”

The direct-drilling approach has evolved at Chaldon Court since the mid 1970s when the Colebrook family farm comprised a small dairy herd and small arable acreage. Over time more ground was rented for cereal crops. A traditional, plough-based establishment regime with lots of labour-intensive, diesel-hungry passes was required to break down the heavy clay furrows into manageable seedbeds.

“I could see that the system we had in place didn’t have a future so I tried using our Massey 30 drill to go direct into stubbles, but it couldn’t get the seed into the ground consistently and our flints just destroyed tynes.

“At the time a contractor with a Bettinson drill sowed all our kale and stubble turnips for the cows. With the stubbles burnt off with Gramoxone it worked well, so we decided to buy our own for the arable ground.”

Slashed costs

The purchase revolutionised crop establishment at Chaldon Court, slashing costs and boosting yields to a point where profit once more became a possibility.

After years of fine tuning they found an approach that gave reliable establishment. To deal with weed issues a pressure harrow and flat roller were pulled over stubbles to generate a stale seedbed. This also helped counteract the Bettinson’s tendency to leave a wide open slot. By producing a fine surface tilth, the soil behind the double-disc openers would crumble back into the slot, making it a much less attractive place for slugs.

“When we made the switch from ploughing we immediately saw crop performance improve, and that was down to fewer slugs, less run-off, and more even germination.

“In fact, by the late ‘70s we were flying – we came second in ICI’s national direct-drilling competition, which looked at whole-farm performance.

“It proved we could outperform conventionally established crops even on our flint-strewn, difficult clay ground. In one crop of winter barley we got 1480 ears per square meter, which resulted in our best ever yields – sadly I’ve never managed to repeat it.”

The success of no-till in the Surrey hills wasn’t experienced across the rest of the country. Grass weed control, compaction, and the ban on stubble burning prompted many growers to turn away from direct drilling. At the time, the arable acreage had grown again at Chaldon Court and more output was required. Power-harrow and tine-cultivator drills followed, enabling the sowing of crops in suboptimal conditions.

“Moving back to more intensive cultivations we slowly saw our yields tail off, often as a result of waterlogging and slug issues – much caused by tillage-induced panning and the almost complete destruction of any soil structure.

“By the early 2000s I was convinced that we needed to return to no-till. The Bettinson had proved the concept would work but it wasn’t without its faults – particularly its tendency to leave an open, slug-friendly slot.

“We’d been in the privileged position of working with Amazone on some of their trial work with combination drills and I’d heard about a new tine-type direct-drill and was keen to be one of the first to try it.”

When the opportunity came up to demo the new Primera, Roger leaped at it.

“It was the first drill that offered a realistic opportunity to return to no-till. The way each knife opener could move independently meant it could work around our flints rather than riding up over them, compromising seed depth.

“We immediately put our name down for it and ended up with the 6m UK prototype.”

That same drill was still doing all the establishment work 15 years later at Chaldon Court – some 1000-1200ha a year with cover and forage crops.

“We saw yields return to what they had been with the Bettinson. You could go in any conditions and as fast as you liked. But when working at 25-50mm it moved way too much soil and, with blackgrass becoming an issue, we needed to minimise surface disturbance.”

Up front is a small-seed/granule applicator that can deliver seed to either of the two distribution heads.

Another drill

Having made the decision that the Primera needed an easier ride and that the target of getting all the autumn crops sown in a week would require more output, he set out to find another 6m drill.

In the autumn and spring of 2017/18 all makes of no-till drills were trialled at Chaldon on the trickiest soils to make sure they could cope with the worst the farm could offer. Some struggled, some failed.

“Pricing varied widely as did build quality and, given that I’m expecting my drills to do a good 20-30 years work, that’s pretty important. It was the Sky that stood out on this front.

“It’s effectively an updated take on the Moore Unidrill concept. I liked the way the discs could bury seed to a decent depth without digging a wide open trench. But where it really outdid the competition was in its ability to sow and drill three different seeds/products at once.”

Roger has been experimenting with different cover and catch crops for decades, aiming to ensure no ground is left bare at any point. While this isn’t always possible, the EasyDrill’s ability to sow different species independently means seed rates can be varied according to conditions.

“Being able to keep seed separate – rather than using mixes – and tweak rates as well as applying slug pellets or Avadex, makes the Sky drill a really versatile tool. We can do so much more in one pass.

“I’ve pretty much settled on using oats, vetches, and phacelia in different proportions according to the season. The ability to alter the ratios is particularly important because we don’t want to end up with too much bulk from any particular species. The combination we’ve settled on doesn’t compromise our take-all situation but it’s vigorous and quick to establish.”

Working into well-established cover crops to sow spring cereals the EasyDrill copes well, cutting through the mat of material to place the seed into tilth at a decent depth.

Seeding depth

The ability to alter seeding depth quickly is a major plus – each bogey-type coulter carriage looks after a pair of openers. To adjust seed placement a locking nut is loosened and simple collars are used to vary how far the discs drop into the dirt.

Hydraulic rams set downforce by adjusting the fore/aft bias on the coulter carriages’ front and rear press wheels. To date the system has worked well – there was just one day last autumn when drilling had to stop.

“We were working on the worst ground we’ve got – extremely heavy clay with large amounts of big flints and baked hard after last summer’s drought. It is contract farmed land that hasn’t had the benefit of decades of cover cropping so it hasn’t had the chance to build organic matter.

“We’ve got similar soils in other places that we’ve farmed for years but because it’s been looked after it can now “self structure” and is workable no matter what the weather has been doing.”

After 1000ha of work in some pretty dry, hard conditions, the opener discs’ scalloped serrations are beginning to wear. The ability to alter the height of the combined scraper/coulter boot means there’s the option to wear the discs right back without compromising seed placement. However, Roger doesn’t want to get caught short and has a full set of wearing metal in the workshop to ensure the drill can keep moving.

“Seeing the discs disappear in last autumn’s horrendously harsh conditions I was nervous about just how long they’d last so I ordered up a new set.

“I was pleasantly surprised at the cost – about £70 (NZ$140) per disc. Although on a 6m drill with 36 coulters that tots up to a fair lump of cash, on a per acre basis it’s peanuts.”

Big saving

Roger estimates there’s a saving of 25-30% to be had by switching from plough-based to direct drilling. But it’s not all about pounds, shillings and pence.

“Putting the potential yield benefits and environmental impact to one side, the biggest saving comes in time. It used to take three months of ploughing, cultivating, harrowing, drilling and rolling to get our autumn crops in the ground – now it’s just five or six days with two 6m drills and a heavy set of flat rolls.

“That means we can choose when to go drilling – always in the best conditions. By sowing cereals at the optimum time we get the best possible results – this is the single biggest factor in direct-drilled crops outperforming conventionally established ones.

“By only going out when conditions are ideal we get uniform crop emergence which directly translates into even growth and ultimately a more uniform crop all the way through. I believe that has a huge impact on yields and, equally importantly, quality.

“But there’s another less tangible benefit – when the direct-drilled crops are up and away nothing else ever looks as good. That provides an enormous sense of satisfaction.”

Key points:

  • Patience is essential – only go drilling when the conditions are right. If it won’t go in the autumn there’s always the option of spring cropping
  • With direct-drilling it’s all about germination – focus on even establishment and everything else will follow
  • Soil structure is the critical factor – focus on improving it by increasing organic matter and rooting, and workability will follow
  • Straw and muck – pretty much everything is baled behind the combine so there’s no issue with crop residue (except cover crops) and it all goes for cattle feed and bedding, returning to the land as farmyard manure
  • Erosion – lots of steep banks means hillsides are always worked across the slope to minimise run-off
  • Rolling – ring rolls achieve very little on Chaldon’s direct-drilled clays. Heavy flat rolls are employed instead to close the slot and conserve moisture.