Trials assess benefits of wider seed bands

The winter wheat and barley were drilled at Essex-based Bentfield Bury Farms using specially imported Bourgault 6in coulters rather than the standard 4in version used there and on other UK farms.

Approximately 800ha of combinable crops are grown on predominantly heavy soils and farm manager, James Mayes made the decision to change from the standard duet coulters on the farm’s 2009 Horsch Sprinter 6m drill to Bourgault Versatile Opener System (VOS) 4in coulters in 2017, as part of a strategy to reduce cultivations and moisture loss either by drilling direct into stubbles when conditions allow, or into min-till, pre-cultivated land.

Bentfield Bury Farms is a family farming partnership where the owners are actively involved in the business. In 2015, Sentry was appointed as a managing consultant, with James Mayes looking after the farm operation. He came to the estate with considerable experience of multiple farming systems and cropping gained through various roles over more than 20 years. He is Basis and Facts qualified and oversees the agronomic policies of the wider Sentry group of farms as agronomy manager.

Wheat is grown for the full GRP 1 market, and last month the farm received the East Anglian Gold awards for yield and potential achieved in 2023, with 10.9t/ha and 81% respectively.

Simple upgrade

Bourgault VOS coulters have paired row tips and place the seed in two parallel strips either side of the opening point. Converting the drill initially requires replacement of the complete Horsch leg assembly with the Bourgault version, while the standard 250mm row spacing is retained.

Once the Bourgault legs are fitted, then subsequent coulter changes are carried out quickly and easily just by loosening a single recessed set screw inside the coulter.

This makes it easy to swap the points for different crops and conditions, and the farm has also invested in a set of Bourgault Single Shoot points to establish oilseed rape and pulses while creating even less surface disturbance to protect against moisture loss.

Advantages retained

Bourgault Tillage Tools UK & European technical manager Stuart Aldworth explained that the nose tip angle is key to the coulter’s successful performance, loosening soil in the seed area while minimising the ‘boiling’ effect on the surface.

“I was enthusiastic about trying our wider 6in coulters in UK soils, as the coulter nose creates most of the soil movement in the seeding zone rather than the wings on either side. This means that the wider coulters will deposit seeds in wider paired bands giving each seed more space and increased seed-to-soil contact for germination and crop establishment, while the low-disturbance action so important for soil moisture retention and minimal surface movement is retained. Obviously being 2in wider, the 6in coulters will move more soil, but the difference in terms of surface disruption is negligible.”

Early tests proved viability

Initially, three 3D printed synthetic coulters were fitted on one side of the drill for an earlier trial in autumn 2020, providing six adjacent rows of crop established by the wider coulters during each return bout. These provided reassurance that larger scale trials would be worthwhile.

The full set was sent from the Canadian manufacturer and fitted to the drill last autumn.

Expecting multiple benefits

“The Bourgault 4in coulters have proved very successful and achieve our primary objectives, but I often feel that the canopy looks too ‘open’ especially in wheat crops which don’t have the tillering advantages of barley,” explained James.

“Using the wider 6in coulters, we drilled the same seed populations per square metre, based on 1,000-grain weights, but the wider seed band allows better spatial distribution. The target is a more consolidated crop canopy to manage in spring which will close up to maximise photosynthesis potential later.

“Other advantages expected could include reduced soil surface moisture due to less exposed soil between the rows, and reduced disease risk due to improved air flow around the plants.”

Spring direct-drilling

James said that with autumn drilled crops established by the new coulters looking well at the end of the challenging wet winter, the 6in coulters could be used to direct-drill crops in the future, and he will trial them for peas too.

“When we direct-drilled peas using 4in coulters the results were very good, but the wider coulters could provide even better creation of crop canopy. This could improve crop standing as the plant rows will meet earlier in the season providing mutual support.”

Promising results

“We are lucky to have the trial set of 6in coulters to use currently, but later we will have to decide whether to utilise the remaining 1,000ha of working life in our 4in coulters or to change to a set of 6in straight away, if yield results from the trial demonstrate earlier investment is worthwhile,” stressed James.

“Our drill operator, Danny Hawkes reported no apparent increase in terms of power or fuel needed to pull the wider coulters, and unless a farm has a particularly severe black-grass issue which means that even a minimal amount of extra soil movement could add to the problem, then I can’t see any disadvantages to using them.

So far, the benefits are as we had hoped, and I think that for some later model drills with even wider leg spacing, then these 6in coulters will provide even greater advantages.”

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