Controlled traffic, parallel bays: HOW IT WORKS

Conventional Contounrs

In the last issue of Ground Cover we promised to bring you more information about Peter Thompsons innovative parallel bays system, which he designed during "many hours in the tractor seat", as Nikki Thompson said. The Thompsons won this year's National Golden Grower award. Here Mr Thompson explains how his system works.

We have found that the parallel bays system has major advantages over the conventional contour system and easily allows varying degrees of controlled-traffic farming.

Our region has frequent severe storms, and this system allows us to let the water off the paddock without taking the paddock with it. I've noticed that when you try to put a fixed concept into nature it tends to come undone immediately. One of the beauties of this system is its flexibility.

How do you set up the system?

I would recommend that you start small the first year, and observe how your layout works before you commit to the position of emergency banks.

Width of parallel bays

There is roughly a 2-metre fall between the emergency banks (similar to the fall between conventional contour banks), and the bays are worked out as multiples of machine widths. Most of ours are five widths of our 14-metre machine — some are six, and some are four metres,in very steep country. The system can be modified to suit the lay of the land.

Grassed waterways

The waterways should be grassed with an appropriate variety, which is controlled by either tillage or spraying up to the edge of it. We spray it back in summer, though this would vary in different parts of Australia — you just treat it as part of your overall farming program.

You drive over (not farm over) the grassed waterways, lifting the machine, allowing furrows to end at a grassed area.

Contact: Mr Peter Thompson 07 4623 0217

Comventional ContounrsParallel Bays
Input costs
  • the irregular shapes of bays mean more work - and the more irregular your country, the more oddly shaped your contours will be
  • because of the extra working on headlands, you use more inputs, time and machinery wear-and-tear than you actually get back in your harvest, when there's no extra product for all that extra input
Input costs
  • parallel bays put some regularity back into the paddock - there are no headlands in parallel bays - which means a straight-out efficiency gain
  • there are savings on all costs: I estimate that parallel-bay-farmed paddocks have a 15 per cent reduction in area and input costs compared to conventional contours
  • natural minor waterways are always weak points in the conventional contour system. If the banks break after heavy rain, you will get major erosion
  • you also tend to get erosion rills forming at the ends of the workings in the bays (see diagram)
  • parallel bays unload into minor natural gullies (grassed strips) which safely distribute stormwater or excess rainwater off the paddocks - you're using the natural system, not working against it
  • because the parallel bays are across the contour, they are still slowing down the water, allowing infiltration
Set-up and maintainance costs
  • you need a surveyor or similar technical adviser to survey the contour lines for you - there must be a certain fall over a certain distance to allow the water to drain properly
  • the cost of building conventional contour banks is relatively high, because of their size (about 1,2-1.5 metres high), and they take up more paddock surface area ('farm-over' banks are even more expensive to build)
  • another issue is that conventional contour banks are a haven for weeds and can't easily be cleaned as part of any normal weedcontrol program
Set-up and maintainance costs
  • parallel bays can be laid out by eye - try out a small area first for a year, before building the emergency banks, and adjust it according to how it seems to be working
  • the cost of emergency banks for the parallel bays system is about 10 per cent of the cost of conventional contour banks, because they're smaller (0.4-0.5 metres tall) and take up less paddock surface area. The smaller size also means less soil is going into the banks
  • emergency banks in the parallel bays system are kept clean or have a minimal grass covering, and because they are lower they can be kept weed-free with a boomspray