Where on Earth are we?

2106-1 DSC_1332webTractors steer themselves. Self-positioning implements place seed, nutrients and cultivators exactly where they are wanted. Wheels stay on defined tracks leaving most of the paddock in optimum condition for plants to grow.

Detailed maps show soil varying within paddocks. Yield maps show different production in different parts of a paddock. Application maps record and prove where inputs were applied.

Animals are tracked and their movement patterns alert farmers to new births. Your stolen four-wheeler is recovered, the thieves tracked and location displayed on GoogleMaps.

Geo-location is the identification of the real-world geographic location of an object. Guided by GPS, we know where on earth we are. We become “spatially aware” and that is the basis of a revolution in agriculture.

Smart farmers depend on the precision of GPS and smart software, and are constantly find new ways to benefit. It leads to changed practice that captures efficiencies and optimises efforts. In the end, it makes things easier.

Self-steering tractors are far more accurate than any driver. They run exactly the same lines every time and free the operator to focus on more important tasks. “The money is made at the back of the tractor, so why spend all day looking out the front?”

As well as providing physical guidance, spatial awareness allows smart farmers to understand their farm in a new way, thinking about points not paddocks, aware of the differences. It lets farmers see how different things relate to one another. Where crop yields are above and below average and how that relates to soil variation. They can tune management to fit.

How accurate can we be, and what accuracy do we need? That depends on what you are trying to do.

Being a few metres out may be okay for some jobs: recording where you take soil nutrient samples, where a water trough is, a rough farm boundary. But for many farm applications, it isn’t good enough.

A good hand held GPS unit will get you within a few metres or so. This simple test demonstrates this:

· Put the GPS unit on a strainer post and record its position or way point

· Use the GPS to steer you back to the same way point later in the day or tomorrow

· See how close you are to the strainer post

You may a few metres out. And if you try again the next day, you’ll possibly be put somewhere different again.

For mechanical weeding, getting close to, but not into, a plant row is important. This requires GPS which reliably gets within centimetres. That entails a very good GPS receiver, and a correction signal using either RTK or CORS to fine-tune the accuracy of the position while the machine is moving.

This level of accuracy is only possible with automatic guidance. Most drivers using GPS for guidance steer within about one foot either side of the line. They can’t make use of a more accurate system because it is actually too hard to follow a guidance system any closer.

Two centimetre accuracy isn’t needed for broad-acre spraying or fertiliser spreading. But some opportunities are missed if a less accurate system is settled for.

When we are unsure of accuracy, we create deliberate overlap to ensure coverage, or create buffers to avoid causing damage.

When spraying, overlap represents overdose of chemical and can result in poor growth in current and following crops. Poor coverage represents under-application giving poor control or the possibility of increased herbicide resistance.

When cultivating, overlap wastes time and fuel, and means more damage to soil for no gain. The ability to return to exactly the same wheel tracks allows considerable energy savings too.

In the end, most cropping farmers want more accuracy and precision as they develop new ways of working with GPS. They all say – buy the most accurate system you can justify.

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