However, there is more to inter-row sowing than simply buying expensive GPS equipment and base stations.

Similar consideration must be given to the equipment to be used, according to a GPS specialist.

Speaking at the recent Southern Precision Agriculture Association conference in Adelaide, GPS-Ag technician Ed Cay said it was equally important farmers pay attention to equipment detail and its tracking ability to maximise to key advantages of inter-row sowing.

Mr Cay said implement size should be one of the first major considerations growers make.

The wider the implement, generally the worse its tracking will be, because depth-control and contour following capability are compromised as implements get wider, he said.

"I believe 18m-plus machines present a real challenge to accurate tracking," Mr Cay said.

"The ultimate solution for wide implements is to simultaneously steer both the implement and the tractor."

Drawbar length is another important consideration in accurate tracking, according to Mr Cay.

"Generally speaking, longer drawbars give more leverage and better tracking," he said.

"A general rule of thumb is that drawbar length should be half of the implement width, that is to say an 18m implement needs a 9m pull."

In the wheel and tyre departments, Mr Cay pointed out that free-steering caster wheels on the front of a machine offered no lateral stability to the implement and, as such, were less stable.

"Front-mounted caster wheels can often carry a load, especially in heavy pulling situation, because implements tend to rotate forward, while the rear wheels carry a lot less weight and so offer little stability," he said.

"On the other hand, tandem wheels tend to want to run straight and, as such, offer more lateral stability than single wheels.

"But it must be remembered it is a lot more difficult to pull a tandem-wheeled trailing machine around a sharp corner than it is a single wheeled machine.

"It must also be remembered that if a tandem axle gets bent, this will tend to make the accuracy of implement tracking a lot more difficult".

Mr Cay also said good depth control across an implement was extremely important for good and accurate tracking.

"An implement that digs in more on one side than the other will skew and track poorly - independent depth control tynes, such as parallelograms, solve this problem," he said.

• Details: ed.cay@gps-ag.com.au