ISTRO Controlled Traffic Farming (CTF) Working
Group
Workshop report
Venue: Jutland, Denmark.
Dates: 16 – 18th November 2005
Organizer: Hans Henrik Pedersen, Danish Agricultural Advisory Service, Århus
http://www.lr.dk/system/Personale/person.asp?PersonInit=HHP
Workshop objectives:
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To exchange ideas about how farming in Europe can progress through CTF
To discuss the challenges and constraints to CTF adoption
To determine what areas of research may be needed to help adoption and system development
Workshop and Danish agriculture overview
The workshop consisted of visits to growers and research institutions interspersed with discussion
forums and presentations. Considerable value was experienced through discussions during bus travel
and during meals at our accommodation.
The organisers provided us with a brief overview of Danish agriculture, which mostly has the benefit of
easily worked soils with a 5 to 20% clay content. In the Herning area in which the meeting was taking
place, soils generally contained no more than 5% clay. Pig production predominates in most areas of
Denmark alongside crops such as winter wheat, spring barley (600,000 ha of each), winter barley,
oilseed rape, grass seed, starch potatoes and sugar beet. Restrictions on nutrient use mean that farmers
must report to government on what they use, with quotas being based on soil type and crop. Quotas are
set at 80% of the economic optimum. Farm size averages about 50 ha, but more and more farms are
growing to around 1,000 ha. Most farms need to be 100 ha to be viable. Land costs 10-25,000 €/ha,
with prices increasing with concentration of pigs in the area.
Visit 1. Axel Månsson (Gartneriet Inger-Marienlund, www.inger-marienlund) near
Brande.
The workshop started at midday on this 390 ha commercial farm on a sandy soil which specializes in
iceberg and cos lettuce, Chinese cabbage, onions and potatoes. 150 ha is under organic production and
there are 17,000 laying hens.
Controlled traffic is employed for growing three successions of field crops within a season. All
equipment is matched on a 2.12 m track and three beds are set up at a time with a cultivator (Fig. 1). A
planter then plants three beds meaning that a 6.35 m controlled traffic system is established.
Inger-Marienlund were the first farm in Denmark to buy into satellite auto steering and presently have
the John Deere Starfire SF2 system. This system is unable to provide the 2-3 cm absolute accuracy that
they need, so next season they will upgrade to RTK, either from John Deere or an alternative supplier.
Lettuce and cabbage are harvested by hand.
Mouldboard ploughing is used to prepare the ground for other crops in the rotation that cannot yet be
established with controlled traffic. In the longer term, Axel hopes that CTF can save them from deep
cultivating (to 45 cm) before growing lettuce. Steaming is employed between successive green crops to
a depth of 8 cm. Steam at 160 deg C and 0.5 bar pressure raises the soil temperature to 80 deg C and
takes between four and eight minutes at each location, depending upon soil moisture. They are trying to
reduce this operation, which is costly in fuel (2500 l/ha on each occasion) but can be justified when the
selling price of iceberg lettuce for example is €45,000/ha.
Steaming is not allowed in organically grown onions so mechanical (including hand) weeding is
employed and this requires between 50 and 70 hours/ha. To reduce this high cost they are presently
assessing the potential of robotic weeding (see visit to DIAS at Bygholm).
1st discussion forum
Bert Vermeulen of Wageningen UR, A&F
Bert provided an overview of the System BEKO CTF project that has been running in the Netherlands
on a commercial farm growing organic vegetables. The project has shown that the following benefits of
CTF can be realised:
Fig. 1. The three-bed cultivator used between successive brassica and lettuce crops
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Good soil structure that provides:
o optimum N-use, less emissions;
o vital crops – improved disease resistance;
o good yield and crop quality.
More workable days, providing:
o ability to spread manure in the spring (soon to become law in NL);
o high yearly machine use.
High productivity:
o large working widths with no problem of matching;
o high work rate and ability to work in the dark.
All operations other than harvesting and ploughing are performed on a 3.15 m track using 30 cm wide
rubber tracks and with implements matched at 6.3 m. Guidance is provided by Geotec RTK GPS to an
accuracy of around ± 5 cm. Crop row spacings are 10.8, 24, 50 and 75 cm. Liquid manure is spread by
a contractor who has the same rubber tracks at 3.15 m.
Harvesting from permanent traffic lanes has proved difficult, particularly in moist conditions. Even
with the rubber tracks, high vertical and tractive loads mean the vehicles slip off are unable to be realigned. Ideas to overcome this problem include:
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An air cushion track
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Use of existing low ground pressure equipment
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Wider wheelways.
A stabilizing disc was also suggested.
If this problem could be overcome, it was anticipated that soil structure would be further improved,
minimum tillage might be possible and more working days would be available.
The BioTrio Farm project
The BEKO CTF project has now extended to 200 ha with the inclusion of a third farmer and is
collectively known as the BioTrio farm. The aim is to investigate potentially favourable effects of CTF.
Following a preparatory year, CTF is now being compared with conventional practice using low
ground pressure equipment. Three crops per year are grown organically on a 22% clay soil and include
green peas, spinach, onion and carrot. Time of sowing and harvesting are the same for both treatments.
Results have shown that:
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Soil air content under CTF is 3% higher than under LGP, the latter sometimes being <10% and
thus restrictive to plant growth.
Emissions of N2O about 20% lower under CTF compared with LGP.
Inter-row weeding is more effective because the soil is more level.
Improved N-use efficiency when yield is increased.
On a 200 ha farm with 30 ha of spinach, break even at 2% yield increase overall, or 8% for
spinach.
Crop yields compared with LGP (=100%)
Year
Peas
Onion
Carrot
Spinach
2002
134
2003
100
93
106
2004
97
104
115 (142)*
2005
102 (117)*
* Machine rather than hand harvesting. This gathers more crop with CTF due to more level conditions
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Penetration resistance in CTF is lower than in LGP.
When growing carrots, mean aggregate size is not significantly different.
No differences in crop quality or diseases were detected between treatments.
As a result of the positive outcomes from the farm study, other farmers in the Netherlands are planning
to set up CTF systems on their own farms, probably based on a 3 m track.
Participant introductions
Participants introduced themselves in turn around the table.
Dirk Ansorge of Stuttgart, DE, is studying for a PhD at Cranfield University, UK on the subject of
stresses below tyres and tracks. He was attending the workshop to acquaint himself with CTF and its
potential to provide practical solutions to the problems of soil compaction.
Lars Nielsen of DK is with the company Autofarm, a Novariant Company that sells GPS auto steering
systems and precision control solutions.
Ole Green of Green Agro, DK is an engineer, agro student and a farmer. He gave a brief introduction to
the controlled traffic system that he has set up on 200 ha and which the group were due to visit. (See
Visit 2) Ole commented that CTF seemed so simple and logical that he found it difficult to understand
why it had not already been more widely adopted.
Paul Cripsey of F.B. Parrish & Son, UK is a farm manager on 400 ha of highly variable land growing
red onions, brown onions, potatoes and combinable crops. Eleven soil types have been identified on the
farm varying from sands to heavy clays. He works on a 1.8 m bed system for most of the season, but
this is lost at harvest and leads to 100 hp/m and 70 l/ha of fuel used to loosen the soil subsequently. He
has bought the John Deere Starfire SF2 system and hopes as a result to avoid “bed making” in the
autumn.
Lotte Knudsen from Bjerringbro in Jutland is responsible for the machinery and its management on a
dairy farm. She was attending the workshop as part of a fact-finding mission with the aim of converting
their grassland management to a system of controlled traffic. Of particular concern was the amount of
traffic that occurred during silage making that required several passes each season. Both direct physical
damage to the grass and soil damage were reducing re-growth and yield.
Richard Price of Patchwork Technology, UK, is involved with “field to plate” traceability, field
mapping, variable rate applications, soil sample mapping, GPS guidance, work recording and targeted
ice control (for airports). He has also worked on integrated steering control, including crab steering and
the ability to turn on full lock while implements are still in the ground. He considered that energy in the
future would be a significant cost factor and that CTF could be crucial in reducing this.
Henning Heuer from the Institute of Sugar Beet Research, Göttingen, DE is currently involved with
research on the effect of compaction on sugar beet growth. Henning was taking the place of HeinzJosef Koch who was unable to attend the workshop due to other commitments.
Andrew Cragg of Brooker Farms, UK farms 600 ha of medium to heavy clays. Combinable crops are
grown in rotation with fresh peas which due to harvest compaction require ploughing rather than his
usual practice of minimum tillage. He is trying to harmonize his farming system with the principles of
CTF.
Odin Gisiason is a Masters student from the Agricultural University of Iceland. He is particularly
interested in the subject of Agricultural Technology and was attending the workshop to listen and learn,
particularly in relation to energy consumption in agriculture. The rotation in Iceland is principally two
years of spring barley alternating with long-term grass leys.
Niels Jakobsen is a Danish farms advisor with around 1500 farmer clients. In 1991 he produced the
first ever yield map and he now works with soil sampling using GPS. This includes lime requirements
and variable rate application of lime rather than fertilizer, which is no longer used. He has also worked
with N-sensors.
Michael Picton of G.T. Picton Ltd, UK owns farmland but contracts it out to a third party. His interest
is in the precision farming aspect of CTF and assessing business opportunities associated with novel
techniques, systems or technologies associated with it. His main business activity at present is log and
timber buildings.
Leif Hagelskjær does advisory work on Funen, DK and has worked extensively with GPS and latterly
with auto steering. He has looked at the variable costs of fertilizers, spray and seed, which on an
average farm cost around DKK2000/ha (c. £180 or €250). He made the point that the spacing between
tramlines established with the drill were often incorrect, mostly with the consequence of over
application of materials. (A similar situation was reported by Richard Price in the UK who had
experienced errors of 1 m in 24 m.)
Knud Nissen from Sweden is closely involved in precision agriculture and the POS project, which aims
to improve the efficiency of Swedish agriculture. As part of this he has produced yield maps from 250
– 300 combines, soil maps from 80–100,000 samples/year and been involved with N-Sensors, precision
liming, P&K applications and weather stations. In 2004 the N-Sensor was used to spread 30,000 ha and
gave a 2.3 % increase in yield with the same fertilizer input. Crop lodging was reduced to almost zero.
Hans Henrik Pedersen (Danish Agricultural Advisory Service and workshop convenor) is based at the
measurement centre of DAAS and believes that the future of sustainable farming depends on high
accuracy positioning. He was impressed with what he saw in Australia when he visited in the spring of
2005. He believes that CTF is an essential part of future innovation. He has been involved with auto
steering, CTF, inter-row fertilizer application, seeding and weeding and machine control, for example
auto boom control. Hans helps with the technology.
Christopher Renner, Normanton Lodge Farm, UK grows sugar beet, winter wheat, oats, linseed, spring
and winter oilseed rape and herbage principally for seed on 360 ha of silty loam and limestone brash
soils. He establishes most crops by direct seeding and aspires to the principles of CTF wherever
possible. Difficulties arise on these soils when direct drilling in the spring and maintaining controlled
traffic when ploughing prior to and during the harvesting of sugar beet. Deep loosening is often
necessary after sugar beet to counter the problems that arise after a wet harvest.
Ed Dale, Pepperdale Farm, UK farms around 1000 ha as well as designing and fabricating drills for
direct and conventional sowing of cereals and pulses. He has travelled extensively and bought and
managed a farm in Canada. He is convinced that CTF has a great deal to offer and is in the process of
converting a large proportion of his farm to an 8 m system based on a common 3 m track width. He is
now offering a customised drill for controlled traffic farming.
Tim Chamen from the UK is a consulting engineer with a 25-year background of research in soil and
machinery reactions dealing principally with the effects of soil compaction on cropping systems. He
presently manages a commercially sponsored project aiming to show that the advantages of controlled
traffic can be realised on a farm scale. The Colworth project is on 8 ha of 40% clay soil and is growing
a rotation of combinable crops using machinery on a common 3 m track with implements 6.67 m wide
matching up with chemicals applied at 20 m. The site is now in its second year and growing oilseed
rape. A short presentation provided an overview of the project and this is available at:
http://www.controlledtrafficfarming.com/content/news.html (see Colworth CTF demonstration)
Visit 2. Ole Green, Green Agro, Ringkøbing (www.green-agro.dk)
Ole Green welcomed us to his 200 ha farm on which he had set up a complete controlled traffic system
based on a 6 m implement module and a nominal 2.75 m wheel track. He is following a traditional
Danish rotation of winter wheat, spring barley and spring oats, but introduces green manures between
crops to improve soil organic matter and structure. To provide guidance he has set up an RTK DGPS
system using the AutoFarm system and AutoSteer. This has two antennae (to correct for roll) that fix to
the vehicle on a single cross beam and can be transferred from one vehicle to another in a few minutes.
Each vehicle has it’s own AutoSteer hardware and interface with the guidance system with both
parallel and curve tracking. Total cost, including the base station (which is located on the top of a high
local factory building) was around €45,000.
Key tractor in the system is a Massey Ferguson 210 kW 4840 selected particularly because of its good
weight distribution. The wheels have been set out to a track width of 2.45 m and the rear linkage has
been especially adapted to accept a 14.6 m3 slurry tanker on a “5th wheel” connection over the tractor’s
rear axle (Fig. 2). This transfers a significant proportion of the weight to the tractor and minimises the
load on the tanker’s rather smaller wheels set on a track width of 2.45 m at the rear. 40 t/ha of pig
slurry are applied in the spring. The principal elements of system are listed in Table 1.
Table 1. Principal machinery used by Green Agro
Prime mover
Track
Implement
width, m
MF 4840
2.45
Dynadrive (two 3 m m/cs welded together)
Horsch drill (track width 2.75 m)
Slurry tanker (track width 2.45 m)
Mounted pneumatic fertilizer spreader
MF 690
2.75
Trailed sprayer (track width 2.75 m)
Mounted spinning disc spreader
MF 38
2.85
Combine harvester
Implement
width, m
6
6
6
18
18
18
6
Fig. 2. MF 4840 tractor showing slurry tanker attachment (inset) over rear axle
Field visits included two green cover crops, both of which showed
significant growth, and the concern with this brassica was that it would
cause problems when sowing in the spring (Fig. 3).
Ole had calculated that he would more than break even in terms of costs
and returns if he achieved an average 8% increase in yields and a 25%
reduction in fuel use.
Visit 3. DIAS Research Centre at Foulum.
We were welcomed on site by Lars Munkholm and Per Schjønning and
were introduced to projects measuring the stresses below tyres and to a
field experiment studying the effects of minimum tillage on crop
production and the environment.
Mathieu Lamandé introduced the work on tyres showing us the array of
transducers that were placed under a special mat on a hard surface or
Fig. 3. Ole Green showing
buried in the soil. Interim results of some of their work were presented
the extent of growth of the
and showed for example that on sandy loam soils, the stresses did not
green cover crop
travel far laterally in the soil, tending to travel vertically. Data were also
shown on the performance of different tyres with loads of 3 - 9 t operating under different soil
conditions. With 4.5 t and a contact area of 0.45 m2, a stress of 40 kPa was detected at 0.9 m depth.
These results will be confirmed and presented at ISTRO 2006.
Lars took us through the minimum tillage trial that was duplicated on two soils, c. 9% clay at Foulum
and c. 15% clay at Flakkebjerg. Mouldboard ploughing, harrowing (at 8-10 cm and 3-4 cm) and direct
drilling with discs are being compared in five different rotations including winter wheat, oilseed rape,
spring barley (with grass catch crop) and peas. Pig slurry is applied to all plots and straw is either
retained or removed. The plots are effectively on a controlled traffic system with tracks at 3 m centres,
but with harvesting and sowing carried out on 1.5 m centres. This was reflected in crop growth that was
more significant at the time of our visit in the centre section that receives no traffic (Fig. 4). The trial
had been running for 3 years and so far only small and inconsistent differences in yield had been
detected in the 15 crops grown. Vertical transparent tubes were being used in this trial, together with
“micro cameras” to study crop rooting.
Per summarised the results of some work they had done in 1988 on controlled traffic. This suggested
that yields under controlled traffic could only be maintained with some firming of the soils, particularly
after ploughing (see Keller et al., 2002).
Visit 3. DIAS Research Centre at
Bygholm
We were welcomed to the Centre by Krister
Persson who presented his and
H. Skovsgaard’s work on the assessment of
different guidance systems. Many
differences were apparent between the
systems, both in terms of pass-to-pass
accuracy and longer-term drift. The full
presentation given by Krister will be made
available to the ISTRO group. One thing
that was obvious from these assessments
was the need for a standardized test, but this
needed funding.
As part of the visit to Bygholm, we were
shown the very extensive fertilizer
distributor testing facility (56 metre wide),
the work on autonomous vehicles and the
OECD cab test facility. The autonomous
vehicle was able to identify specific weeds
(or crops) through the use of a “finger
printing” technique that characterized
specific features of a plant. This was
demonstrated in the laboratory by its ability
to spot treat closely defined areas laid out on
the floor.
Fig. 4. A plot of the minimum tillage experiment
showing the rather better growth in the centre
section of the plot that is effectively controlled traffic.
Closing discussion session of the ISTRO CTF Working Group
Hans Henrik asked the group to write on a white board a single topic that they would like to discuss.
Tim Chamen then chaired the debate that centred on aspects of CTF that either needed clarification or
that should be promoted when speaking about the system.
Flexibility. There was concern that CTF reduced flexibility in farming systems. This is unlikely to be
the case in the long term because CTF only promotes the principle of not driving on the cropped area.
All things are possible with a bit of innovation. An inherent constraint with the system is that
operations cannot be carried out an angle to each other. This means that we may need to develop soilengaging equipment that levels rather than ridges the soil.
Standardisation
We should not create the perception that CTF in Europe can only be on 3 m tracks. A number of
different options are now available, all of which deliver the principle of CTF (see
www.controlledtrafficfarming.com/? Due to different road regulations and the fact that many European
tractors carry a lot of weight, solutions with around 2 m tracks should be included.
With a large variety of crops in European farming, standardisation is difficult. Pioneering farmers need
to be innovative when making solutions for their farms. Setting up CTF often needs long term
planning, as most farms cannot change all machinery in one season.
Promotion of CTF.
It was suggested that we concentrate on the benefits that CTF can deliver, such as easier working soils
that enable more effective and reliable minimum tillage and direct seeding. Clear irrefutable messages
about CTF benefits under European conditions are needed. A folder including" What to consider"
would also be a good initiative.
Promotion is most effective through case studies, more of which will be included on the website
(www.controlledtrafficfarming.com/content/casestudies.html). The farm of Ole Green in particular will
be considered as a new case.
Take-away messages from the workshop
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The main argument for CTF is “in the wallet” – it gives more yield with lower inputs
CTF is not about tillage, it simply means you have to do less of it.
Soil compaction is a major limiting factor mitigating against optimal plant growth, but because
compaction is so widespread, it is difficult for farmers to recognise the problem. Due to many years
of driving at random over the soil and ploughing in the furrow, compaction below 25 cm is
common in European farming.
 Staying on the wheelways with high loads in moist conditions is a challenge. Disc-type
stabilizers may be the answer.
 CTF is about innovation and engineering – it isn’t rocket science!
 Steering with satellite guidance is an enabling technology but is not the only means of achieving
CTF.
 High accuracy systems increase the potential for precise operations, such as injection of fertiliser
and inter-row seeding and mechanical weeding.
 The combine harvester is the vehicle with the widest track width. Matching other equipment to
this in European conditions may not always be desirable or necessary for achieving a controlled
traffic system.
 CTF as a farming practice in Europe is emerging as an option for UK progressive farmers. This
is now becoming the case in the Netherlands and Denmark. The group knows of no other initiative
in this area.
Tim Chamen.
Hans Henrik Pedersen
December 2005.
Attendees at the CTF Workshop, Denmark, November 2005
(Photo John Christensen, Maskinbladet)