- The longest run may not always be the best option in designing controlled-traffic farming (CTF) layouts. Consider the impacts on harvest logistics, water flow and stubble shading.
- CTF is just the first step in improving soil health and the long-term profitability of a cropping system.
Unlocking your full production potential is a complex challenge best managed by taking a farming systems approach. This means planning is critical, and designing an efficient and effective controlled-traffic farming (CTF) layout is a good example of this.
In a perfect world, permanent wheel tracks are only set once - so getting it right the first time is the top priority for CTF systems.
Factors to consider when determining direction of operation (AB lines) include:
- operational efficiency - the longest run;
- harvest logistics - unloading the harvester and moving grain out of the paddock;
- surface water management - limiting the effects of waterlogging;
- soil erosion - wheel tracks can wash out during heavy rain events; and
- stubble shading - east/west inter-row seeding into tall stubble will increase shade for emerging crops and weeds.
Managing erosion risk
The priority of these factors will depend on climate, soil type, grower preferences and farming system. The factors that are important for a continuous cropping system can be different to a mixed farming system, especially when managing erosion risk.
Crop rotation and the level of retained stubble also play a key role in determining run-off risk, which will help inform layout decisions.
Most paddocks can follow one direction of operation. However, complex landscapes with low water infiltration rates (such as heavy clay paddocks in the high-rainfall zone) may need to be split into several different layout blocks to optimise surface water flow.
While the longest run is generally the preferred option for the direction of operation (see Figure 1), this can not always be achieved if the direction compromises harvest access, surface water management or soil erosion.
For example, there are numerous paddocks throughout south-west Victoria (basalt clays) where the existing direction of operations (AB line) has suited most of the paddock, but compromised the water flow in some areas. These areas are frequently waterlogged and difficult to access during wet periods. Changing the direction of the run to align perpendicular to the slope rather than parallel will significantly improve the flow of run-off water.
Strategic spoon drains can be integrated into a paddock design where waterlogging is a risk (see Figure 2). Seeding rows are best directed downslope, creating a corrugated iron effect where excess water can be picked up by drains. Soil cover is vital to minimise soil erosion in these downslope layouts.
Strategies that deliver the greatest return on investment will be those that address issues causing the greatest pain to your business.
The bigger system
A well-designed CTF layout is only one driver of long-term profitability in a cropping system.
By improving soil health, CTF opens the door to a wide range of soil and crop management strategies that can deliver significant benefits to a farm business and the environment.
Many of these strategies can be intensified by integrating spatial soil and crop mapping to deliver targeted management of soil constraints.
For instance, inter-row seeding enables stubble retention, which improves water infiltration and soil carbon levels. Soil cover is king as stubble also plays a critical role in minimising water erosion from intense rainfall events (see Figure 3).
In recent years, paddocks have been merged into larger blocks in the pursuit of operational efficiency. However, this is a shift away from the early principles of farming to landscape and soil type.
To overcome this variability a considered farm management plan integrating CTF and precision agriculture can unlock crop production potential and build resilience against an uncertain climate.
Common yield constraints managed through such plans include compaction, sodicity, waterlogging and acidity.
A digital elevation map (often able to be generated from farm operation data) is the ideal starting point for designing layouts as it enables the integration of drainage and water-erosion strategies.
More information: Andrew Whitlock, Precision Agriculture Pty Ltd, 0458 312 589, firstname.lastname@example.org