Changing to CTF
Ultimately all machinery wheel tracks should match to confine the wheels of all heavy machinery to permanent traffic lanes, however larger headers, off-set fronts or airseeders wider than 12m can make matching difficult. To make the process of converting to CTF manageable, developing a machinery investment plan to enable changes within the farm budget is recommended. This may be a plan over a few years. Estimated benefits can help plan pay back times of foreseen costs.
Steps to develop a machinery investment plan
- Decide on imperial or metric measurement (this applies to machines and row spacing).
- Select an operating width and match in multiples (multiples of 9m or 12m are most common).
- Match the tracks (for wheels or tracks with more than a 1t load). Work off header size as it is the most limiting. Ensure machines can go to 3m wheel centres
- Choose the type and width of wheel track you want to leave (fuzzy, bare etcetera).
Before getting out the gas axe to modify machinery widths or axles, experience has shown it is better to measure twice and cut once! In particular, make sure you check the actual cutting width of the header and set the bar width accordingly to avoid leaving unharvested rows of crop.
Components of a CTF system
CTF needs accurate and repeatable guidance to be able to return to the permanent wheel tracks every time. Global Navigation Satelite System (GNSS) Real-Time Kinematic (RTK) 2cm guidance provides this and is the recommended option. It is likely that proprietary equipment (where one brand is not compatible with another brand) will decline and this will further benefit the industry. In addition, service from Continuous Operation Reference Stations (CORS) Networks and other networks are widely available and this reduces the capital investment. High-quality guidance delivers autosteer, which provides accuracy and reduces driver fatigue. Generally the bigger the cropping area, the greater the savings from preventing overlap by using electronic guidance. Growers with programs greater than 1500ha and input costs of about $100/ha have made savings of about 10% by using an accurate electronic guidance system. This goes a long way towards rapidly recovering the cost of the system. Many WA grain growers no have electronic guidance systems (GPS) and are well positioned to move to CTF. Some growers still chose to use mechanical guidance systems and centre guide row systems in the crop.
Ideally, all machinery tracks and widths should match, but large grain harvesters with wide wheel tracks, offset harvester fronts and air seeder bars wider than 12m can make matching difficult, often due to the minimum distance of spreading straw or fertiliser. As moist soil is the most easily compacted, spraying and seeding equipment is the most important machinery to match. If you have lots of easily compacted sandplain soil or tend to have wet harvests, serious consideration should be given to incorporate the harvester in the CTF system.
Following is a list of convenient harvester widths, along with the seeder and sprayer widths to which they match. Odd matching ratios of sprayer to seeder (3:1) allow neater paddock edge matching. Even ratios (2:1) need overlap runs at the edge or an extra set of permanent wheel tracks in the wings of very wide seeders.
- Harvester widths: 9m, 10.5m, 12m, 13.5m
- Seeder widths: 9m, 12m, 18m, 21m, 24m
- Sprayer widths: 18m, 21m, 24m, 27m, 36m
However, machinery changes can be expensive, depending on what is already owned. A machinery plan outlining wheel track and implement width is needed. Machinery can then be changed over as part of the farms usual machinery replacement strategy. This may take 5-10 years to have a fully matched system. Eventually there can be less machinery and possibly smaller tractors due to better traction and lower draft requirement.
Many growers have been using partial CTF where the header or some spreading operations or a contract SP sprayer do not fit the whole system. Such partial options still provide some benefits and may be more cost effective for some environments and farm budgets. It is important to review the plan as time goes on to optimise profitability and sustainability.
Why match in the grain harvester?
There are several reasons why matching the harvester into a tramline system is a good idea.
- Harvesters and chaser bins are the heaviest equipment on most farms and cause soil compaction during wet harvests or where soil is moist from shallow water tables. This compaction can be severe enough to remain for many seasons.
- Harvesters will thresh and separate grain more efficiently when large amounts of power are not being used for traction, especially when harvesting on recently deep ripped sand.
- On-ground guidance from spraying tramlines can be confused by wheel tracks from harvest that do not match the tramlines for the other operations.
- There may be integrated weed control options (weed seeds and chaff from harvesters dumped on tramlines), which could be more efficient than chaff carts.
- Full matching of the cropping machinery allows best soil improvement for long term benefits and possible savings in fertiliser requirement.
If you are planning to fit the harvester in, then it is best to base the widths and tracks of the whole system on the harvester because the harvester can be the most expensive piece of equipment to modify. Harvesters with 11m fronts are commonly offset and cause difficulties for matching into 'up-and-back' operations (not such a problem for round-and-round operations), however up to 14m centred belt harvester fronts are now available. If matching the harvester initially requires substantial modifications it is possible to start with matching the seeding and spraying equipment and includes the harvester later. Controlled traffic operators in Queensland who have been in CTF for up to five years are finding that after initially matching only the spraying and seeding equipment they now wish to include the harvester. To accommodate this they are modifying their equipment to 3m tracks.
Traditionally tramlines have been left bare. However, due to concerns with herbicide resistance, gaps in the crop and potential erosion on non-wetting sands (particularly in Western Australia), tramlines are best sown with crop, but with short points or discs to retain firm running.
Whole-farm planning is important when introducing new technologies such as CTF into your system, as a change in paddock layout is often required to utilise the effectiveness of the new technology.
Useful tools for planning layouts include aerial photographs, farm maps, topographic and soil type maps, even yield maps and of course, knowledge of the farm. CTF is compatible with precision agriculture (PA) technologies, such as variable rate technology (VRT). Some changes may take more than one season to put into practice but it is helpful to have a plan for the future. If in doubt about layout contact a professional consultant, as layout mistakes may cause severe erosion damage and are often expensive to remedy.
Design of the most efficient layout considers:
- Length of run
- Access roads
- Tramline orientation
- Surface water control
In high-rainfall areas, all wheel tracks should drain down to a safe disposal area. This allows water erosion to be managed by preventing any flow concentration so wheel tracks do not erode. Waterlogging can also be managed with raised bed layouts in the high-rainfall zone. In practice, there will be low areas in most fields which require drainage.
Experience in Western Australia of water erosion in CTF systems
Source: (Lemon 2006)
The heavy rain in early January 2006 provided a good opportunity to observe the stability of wheel tracks and raised bed drains on sloping land in Western Australia.
Interviews with several growers indicated that erosion had been minimal in parallel cropping systems running down slope. Comparisons with pasture paddocks and previous working patterns indicated that erosion could even been less in down slope working patterns.
The main problems were where water flows concentrated before finding a down hill wheel track or furrow, such as water running out of a reserve onto the paddock or a flat area within a CTF paddock where water moved across working runs prior to finding a sloping wheel track.
Other observations included:
- Erosion was worse on tracks within paddocks than on the wheel tracks
- Cereal stubbles provided more protection than pea stubbles
- Sown wheel tracks and furrows offered more protection than bare lines
- Older raised beds were more stable than newly renovated beds/furrows
- Erosion was a bit worse on wheel tracks on loamy and clay soils compared to sandy soil.
The rationale that many small furrows carrying their own water causes less erosion than a few large depressions carrying accumulated water from larger areas seems to have ‘held water’ in the 2006 extreme rainfall event.