Take Home Messages

You cannot afford to not implement a Controlled Traffic Farming (CTF) system which is basically the same as raised bed farming but without raising the bed. This is increasingly being referred to as flat bed farming. There is now a great deal of evidence that says your farming system cannot evolve to its potential until you have adopted this simple yet advanced management system.

We now know that

• Wheeled soil compaction is limiting your yield potential
• One wheel pass limited reduced yield by 30% at four different locations with different soil types
• 80% of the damage to soil structure is created by just one wheel pass
• Even with direct drilling approx. 80% of a paddock will be covered by wheel tracks every season
• CTF limits wheeled compaction to 15-20% of a paddock
• Other benefits of CTF include improved trafficability less input costs (fertiliser and chemical savings) reduced fuel bill night operations improved agronomy options less driver fatigue and a simplified system
• CTF adoption exceeds 1000000ha across Australia - it is here and it is the future.

So have a go! CTF is easy to implement and delivers significant farm management and financial benefits

Definition of Controlled Traffic Farming

CTF is a smart healthy cropping system which delivers production environmental and efficiency benefits to those who implement it. It literally means to control where you drive during cropping operations by driving along clearly defined permanent wheel tracks with the aim of minimising the area affected by wheeled compaction. By doing this we separate our paddocks into sections one which provides a healthy well structured medium for supporting crop growth and one which provides the roadways for supporting vehicles and machinery. Raised bed farmers do all those things as part of their bed and furrow system.

The ultimate CTF system is achieved by matching both the wheelbase widths and working widths of all implements. Ideally this should include the header. For Controlled Traffic a common wheelbase width is 3m which limits wheel compaction to 15-20% of the paddock. (With raised beds the bed width often 2m determines the wheelbase width to be used). The first step towards Controlled Traffic however does not have to achieve this ultimate machinery matching system. It's important to start by working with your existing machinery and be flexible. At least matching the spreader and sprayer to be a multiple of the seeder (tramlining) is a fantastic start.

The Project

Soil compaction costs agriculture up to $850 million every year in lost production however there are many farmers who are unaware of its presence. Managing compaction makes sense and there is a lack of understanding particularly in Victoria about the effect it has on crop growth. In season 2004/05 DPI Precision Agriculture Agronomist Andrew Whitlock conducted a pilot study investigating the importance of CTF in Victoria through measuring the effect soil compaction has on crop growth. The project consisted of four key case studies of CTF systems; a range of Victorian grower surveys investigating attitudes and potentials to adopt CTF; an investigation into CTF in the Mallee; and a detailed investigation into the effect wheel compaction has on crop growth. This paper focuses on the results from the soil compaction research.

Results

The research component of this project aimed to quantify the effect of wheel compaction on crop growth. Measurements were conducted on four farms at different locations lupins at Woorndoo and barley at Lismore Winchelsea and Balliang.

Crop Establishment

The average reduction in germination rates along wheel tracks was 30% for barley and closer to 70% for lupins. The seedling heights along the wheel tracks were also reduced at all four locations. The seeds not only struggled to penetrate the compacted surface but eventual germination was delayed and seedling vigour was reduced.

Crop Development

Crop growth measurements were collected at three different times throughout the season (September October and December). The crop growth along sowing only tracks was clearly less than the corresponding growth of between tracks at all four sites and for each date of sampling. The differences varied between locations but were in the order of a 50-20% reduction of biomass along sowing only tracks.

At Woorndoo and Winchelsea the spray tracks were sown but this was not the case at the Balliang and Lismore locations hence the incomplete data sets. The biomass measurements along the spray tracks were considerably lower than the corresponding measurements for both between tracks and sowing only tracks. This effect is caused by the combination of compaction and physical traffic damage.

Tiller densities were also reduced along sowing only and spray tracks to a far greater degree on the spray tracks. The data sets from all four locations confirm the theory that even just one wheel pass can have major effects on crop performance.

Soil Observations

The level of compaction caused by machinery was determined through measurements of soil bulk density and soil moisture. These basic measurements highlighted the fact that random wheel traffic can compact the soil to a point where root penetration and soil water storage is severely limited. The measurements along the spray tracks (numerous passes throughout the year) showed bulk density readings exceeding the upper limit for root penetration of 1.6g/cm3 at two of the four sites. The greatest impact was measured in the top 15cm. The one wheel pass at sowing also increased bulk density thus limiting plant available water at all four sites.

Final Yield

This study of four different paddocks with different climate and soil types has found that one wheel pass at sowing will reduce crop yield by ~ 30% and numerous passes can reduce yield by ~ 80%. The yield reduction of spray tracks is a result of both compaction and physical traffic. The data highlights the damage that can be caused by just one wheel pass and the need to manage wheel compaction.

This data accurately reflects previous research where CTF delivers a 15% yield benefit.

Where to begin with Controlled Traffic Farming

1. Sowing up and down rather than round and round is the first step towards improving paddock efficiency and to managing wheel tracks.

2. Seek professional advice for determining your property design and paddock layouts. A contour map may well be required for this. Be flexible and prepared to remove internal fences.

3. Guidance is the essential component of a successful CTF operation and the best way to minimise overlap at sowing and spraying is through the use of GPS. However there are less expensive options. Many farmers begin by employing a GPs equipped contractor to mark either their spray lines or sowing lines. The option of marker arms on the combine or airseeder also provides improved accuracy.

4. Develop permanent wheel tracks which provide the ability to drive along the same tracks from year to year. Autosteer (2cm accuracy) with RTK base stations are the only GPs systems which provide the level of accuracy to successfully do this. Permanently bare wheel tracks avoid the need for autosteer but need to be accurately set-up (line marked with 2cm autosteer) from the start.

5. Decide on whether you will match the header (3m system) or if you will start with a 2m system. Modify tractor and implement wheelbases according to this decision.

6. Modify existing equipment or purchase new gear to ensure the working widths of the spreader and sprayer are a multiple of the seeder (ie 8m seeder 24m boom 24m spreader).

7. Getting professional advice for planning mapping and implementing is recommended if you do not want to reinvent the wheel.

Selecting a suitable guidance system

Marker-arms on the seeder are an easy and cheap form of guidance and can be homemade. While marker arms provide an effective level of accuracy they are not ideal for certain operations such as inter-row sowing. Getting a contractor to mark lines is another cheap and effective way of getting on track but there are obviously issues with availability and confidence in their job. Contract rates will vary with operators.

The ultimate guidance is obviously GPs and the big issue with this is the cost. However the cost of auto-steer has reduced by basically 50% since its introduction and is thus becoming a more realistic option. Should you decide to get GPs guidance then you will need to have a good think about what you want. The performance and accuracy of auto-steer systems vary and the year to year (static) accuracy is critical for CTF. 2cm RTK base station auto-steer is by far the best and it won't be superseded. Seek advice when choosing these guidance systems.

Benefits observed and measured throughout Australia

Efficiencies

• Significantly reduced inputs (3-15%) through less overlap
• Reduced fuel consumption (up to 50%) due to improved traction and reduced draft
• Easy guidance less driver fatigue more attention on the implement and its operation
• No need for foam markers it makes driving EASY
• Ability to spray at night through improved in-crop guidance
• Wider window of opportunity for operations - improved spray efficacy

Soil Improvements

• Confines soil compaction to the permanent wheel tracks
• Allows soil structural improvements through drying and wetting cycles biological ripping by plant roots and incorporation of organic matter
• Improved water infiltration rates and greater ability to store plant available water (PAW)
• Greater porosity means more oxygen in the soil which is essential for microbial activity and soil health

Environment

• Better infiltration means less water run-off which leads to improved water quality and healthier catchments
• Improved soil health
• Ability to spray in better conditions (ie. at night when wind is less prevalent)

Production

• Enhanced root growth with a greater amount of secondary root fibres
• Soil is capable of holding more moisture
• Accurate guidance enables inter-row sowing spraying etc
• Guidance also improves the ability to retain stubble if that is desirable
• Improved soil structure will help to alleviate waterlogging
• Improved water use efficiency of the crop
• Improved timeliness of getting onto the crop after rain
• Yield increase of 15% (greater in years with a dry finish)

Conclusions

Cropping systems across different landscapes and soil types are suffering from soil compaction. Compaction is a continuous process ultimately resulting in a loss of soil macro-porosity leading to low storage/supply of water and oxygen and increased soil strength. This investigation of the effect of wheel compaction on crop growth supports the need to actively manage soil compaction. Wheel compaction reduced crop establishment leading to poor crop growth and reduced crop yields at all four sites. One wheel pass at sowing increased bulk density of the topsoil at all four sites limiting root penetration and plant available water.

Controlled Traffic Farming is generating a lot of interest and is being widely adopted across Australia. The benefits are delivered through a range of areas of crop management such as time efficiencies making life easier improved soil health better crop growth and higher yields increased accuracy of operations and reduction of inputs.

Further work is required to help farmers adopt changes to farming systems. There are many farmers across south west Victoria keen to implement CTF but who require support in order to make the jump. Coordination among DPI SFS local agronomists and other key stakeholders would benefit the wide scale adoption of strategic efforts toward the active management of soil compaction. Controlled Traffic Farmer Groups are being set up to provide growers with support from other farmers and from agronomists.

Quotes

Russell Taylor (Darling Downs - Qld) "If nothing else CTF makes life simple you don't have to worry about foam markers and you just follow the wheel tracks".

David Langley (Winchelsea - Vic) "The psychological hurdle of changing your farming system is the only reasonable explanation for not wanting to adopt controlled traffic farming".

Rob Taylor (Darling Downs - Qld) "It's a sustainable farming system which increases my ability to harvest soil moisture and sunlight".

Hugh Ball (Mooree - NSW) "We've seen great benefits in crop production - which is due to improved water infiltration and extraction".

Troy Missen (Shelford - Vic) "It forces you to get out of the round and round mentality and improves the general ease of operations".

Lachie Seears (Lucindale - SA) "We're in a high rainfall zone of above 650mm. For me the biggest benefit of controlled traffic is that it gives me 12-month paddock access. The compacted wheel tracks enable in-crop operations whenever I like".

Ian Carter (Qurindi - NSW) "It's amazing how much of the paddock is actually compacted from wheel tracks if you're not into controlled traffic. We've matched all our machinery and we're committed to the system".

Lindsay Chappel (Perenjori - WA) "Depending on how accurate we were previously savings of 3 to 10 per cent can be achieved. Fertiliser is a single large item where big dollars can be saved'.

Neil Diamond (Buntine - WA) "The input cost savings are too great to ignore. The system has allowed us better opportunities for relay planting summer crops and perennials (lucerne) and the use of shield spraying in lupins. Once the driver has learnt how to use the navigator driving has become easier and less fatiguing".

Acknowledgments I'd like to thank the cooperation of the four farming families involved with the Project. Particular thanks go to David Jamieson Tom and Sam Dennis James Bufton and David Langley.