Unilever R&D Colworth Controlled Traffic Farming Project

Project initiation, 2004

(Project extension, 2006)

In September 2004 a group of industrial partners and farmers came together to formulate and trial a controlled traffic farming (CTF) system in the UK. The aim was to learn about the practicalities and sustainability of CTF, monitor its benefits and shortcomings and assess its commercial potential for the farmers involved. Partners in the project included Unilever R&D Colworth, John Deere UK Ltd, John Dale Zero Till and Farmade Management Systems. Michelin Tyre plc also provided active support. Eighteen farmers were involved representing more than 10,000 ha of arable land in the UK.

The CTF system was based on an implement width of 6.67 m and a tramline of 20 m which matched with the existing farm equipment (see illustration). To match the harvester track width and minimise the area wheeled, John Deere provided an 8520 tractor with Independent Link Suspension and axles extended to 3 m. John Dale Zero Till modified one of their drills to fit the system and a harvester was brought in by John Deere.

Colworth: Initial system

Illustration of the initial CTF system at Colworth (approx. to scale). In 2006 the primary implement width has been extended to 8 m and the chemical application to 24 m, while the wheeltrack remains at 3 m

Guidance for the vehicles is with a single John Deere Starfire receiver and key card which we swap between harvester and tractor. We are using the SF2 system which has delivered the predicted accuracy (well within ± 10 cm) but we had to install a datum point to make sure that we returned to exactly the same tracks each time. In the particular field, access to the datum point was easy as there was a concrete track and grassed headland alongside.

Many cost-effective and simple ideas are emanating from the project and a number of the farmers are now actively pursuing conversion or have converted to CTF.

Results from the single 8 ha field in CTF at Unilever R&D Colworth have been encouraging. Within about 12 months the topsoil conditions improved compared with surrounding conventional practice on the same soil (see photos) and some comparisons of water infiltration indicated a substantial increase over similarly managed but trafficked soil (see table). The results for ploughing might appear impressive, but there was marked evidence that the water infitrating rapidly from surface was merely going to plough depth before being held up by a compact layer. Although we were unable to harvest the crop of wheat at the end of the first year (nothing to do with the fact that it was in CTF), the subsequent crop of oilseed rape grew vigorously (see photos) and yielded 4.2 t/ha. Although this was no greater than yields from surrounding fields under conventional management, lack of any replication of treatments would not allow us to make valid comparisons. Penetration resistance was also lower on the CTF field than on neighbouring direct drill or low input systems but higher in the topsoil than on a ploughed field.

Conditions were very moist and soft when we first introduced the CTF wheelways so we made an initial in-filling pass with a cultivator. Since then the permanent wheelways on the CTF site have remained in good condition with no further management needed.

Farm staff report the system is easy to operate and the guidance system has worked well.

Colworth: Topsoil 12 months after introduction of CTF

Topsoil twelve months after the introduction of CTF and direct drilling

Colworth: Topsoil in an adjacent field that was direct drilled with random traffic

Topsoil in an adjacent field that was direct drilled with random traffic

Colworth: Topsoil in an adjacent field where non-inversion tillage had been used with random traffic

Topsoil in an adjacent field where non-inversion tillage had been used with random traffic

Water infiltration on the CTF site compared with that on surrounding fields under conventional traffic management (December 2005)

Treatment Mean infiltration, mm/h Standard error
CTF direct drilled 904 167
Minimum tilled (discs) 576 102
Direct drilled (tines) 179 69
Ploughed 5264 1553

Project extension, 2006

As from September, the single 8 ha field converted to Controlled Traffic in September 2004 on a clay soil was augmented by eight others, bringing the total area to 73 ha. Wheat and oilseed rape were direct sown and winter beans were similarly established soon after. Some of the new fields going into CTF were deep loosened; some because their condition was known to be poor, but others were loosened to provide a direct comparison between fields that were in the same position in the rotation. We will look at the relative performance of the crops in these fields as well as the soil conditions. As the conditions were very dry when the first CTF wheelings were established on these new fields, no in-filling has so far been necessary, but this situation will be reviewed after harvest next year.

Guidance of the vehicles remained initially with the John Deere SF2 system, but as we wanted to keep the wheel tracks in exactly the same place from year to year we tried installing permanent markers to reset the initial position each time we came into the field. More learning and experience soon showed us that this had no chance of working, so with some further sponsorship from John Deere, we changed to an RTK system in summer 2008. In summer 2008 we also changed from our initial ComTrac system of 3 m tracking for all vehicles to an OutTrac system, where a John Deere 7930 was set to a standard track width of 2.2 m and the harvester was set at its minimum track width of2.65 m. This arrangement meant that we had no axle modifications and we had the maximum overlap between the two track widths. Tracked area, including the harvester is now just under 25% but under 17% if we consider only the tractor and drill. The site continues to be managed with the OutTrac CTF system within a five year rotation of wheat, beans, oilseed rape and a spring crop. Members of CTF Europe are welcome to visit the site by arrangement at no charge. Non-member groups may visit by arrangement with the farm manager and CTF Europe and on payment of a small fee. Contact Tim at CTF Europe for more details.

We would like to thank the following companies and organisation for their sponsorship of CTF at Colworth and for their support for other events and activities undertaken by CTF Europe. CTF Europe is an independent company which otherwise relies on consultancy and its membership to fund its activities, reports and information.


John Deere

John Dale Drills