- Reducing compaction by controlling traffic in the cropping phase will also benefit the grazing phase in a mixed farming system
- Livestock only compact the topsoil and this is easily remedied by the action of sowing crops
- Machinery for fodder management is now available for permanent wheel-track systems
There is a perception that mixed farming is not compatible with fully matched controlled-traffic farming (CTF), but there is no reason why the two systems cannot work together.
In fact, the benefits of CTF can be carried into the pasture phase if the same principles are used.
True mixed farming, where the same paddocks are used for both grains and livestock, remains a proven and successful system across much of the Australian grainbelt and can often be important for profitability and risk management.
Impacts on soil
Heavy cropping machinery damages the structure of both the topsoil and subsoil to considerable depths, sometimes down to 40 centimetres or more, reducing the performance of crops.
Grazing by hard-hoofed farm animals also damages soil structure, but there is a crucial difference between machines and animals.
Machinery damages the soil to a depth proportional to the axle load (often 10 to 12 tonnes) and the width of the wheel or track (often about 500 millimetres).
Damage from sheep (about 60 kilograms) or cattle (about 800kg) on four hoofs (about 50 to 100mm across) can be severe, and can reduce moisture infiltration, but is confined to only a very small part of the top of the soil profile.
This shallow damage is relatively easy to remediate, for example with tyned seeders in each cropping phase. Whereas the deep topsoil or subsoil damage from machinery may last for many years, especially in sandy soils.
Once all the cropping areas on a mixed farm are laid out and set up for CTF, the layout and the AB lines that guide machinery remain the same, even while paddocks are in the pasture phase.
When cropping resumes, both the permanent traffic lanes and the CTF benefits will persist.
We can learn a lot from controlled-traffic cropping about the best ways to manage grazing animals and pastures to minimise soil damage.
In a pasture phase, it is still sensible to avoid driving heavy machines and vehicles randomly all over the paddock unless strictly necessary.
Like crops, pasture plants often perform better in uncompacted soil, and both plants and soil can be damaged by overgrazing.
It is important to mnage stock densities to minimise the risk of overgrazing and maintain good stubble cover to limit erosion and damage to soil structure, regardless of whether CTF is in place or not.
Sheep in CTF stubbles tend to prefer to use permanent tracks as pathways because of the firm ground and will preferentially graze the chaff lines. If water points are being established, they are best placed at the ends of the CTF runs.
There are many good examples from across Australia that show running a mixed farm is no barrier to controlled-traffic farming adoption.
Wet conditions make soils more vulnerable to compaction by machinery and livestock. If possible, sheep grazing dual-purpose crops at the start of the growing season need to be removed before the soil becomes too wet.
Likewise, livestock grazing stubble may need to be removed from heavier soils after summer rain and shifted to non-cropping areas until paddocks dry out.
It is now possible to cut and bale forage and straw without running the machines off the permanent CTF lanes.
As with CTF grain production, a planned machinery replacement program will achieve a full CTF forage production system over a number of years.
Admittedly, mustering can involve random traffic and may be a bumpy ride when crossing the wheel tracks, but this is less of an issue on a motorbike.
There will always be compromises in running a mixed-farming system, but the improvements in soil fertility and crop and pasture growth that flow from controlling traffic cannot be overlooked.
There are many good examples of mixed farms from across Australia where high-yielding grain crops are combined with sheep enterprises, cattle studs and even free-range pig breeding enterprises.
They show that running a mixed farm is no barrier to CTF adoption.
More information: Chris Bluett, ACTFA, 0409 336 113, firstname.lastname@example.org