If PA adoption was a hurdle race, the gun went off a few years ago and the first hurdle was guidance. Guidance was successfully developed, quickly followed by auto-steer. We can pretty much say that all entrants cleared the first two hurdles.

The third hurdle was yield mapping, and here we saw the first crash out because the software was very complicated! A couple of others clipped the top but continue off stride. Hurdle four, Variable Rate Technology, known to all and sundry as VRT. Carnage! Bodies all over the track, with one or two limping to the finish line. It was so good up until then…

What happened? The machine dealerships and companies have a lot to answer for. Lack of local support with the attitude, “Once it leaves the lot, the PA is your problem,” or, “Call the 0800 number” is very common.
In the past year I have seen $300k machines with factory guidance systems have to be re-booted twice a day because the system freezes. And the dealer can’t fix it. I see new VRT gear that can’t talk because its software is years out of date. It takes weeks to find out why, weeks to fix it and farmers just have to accept it. I am glad they don’t build aircraft.

Until the hardware problems are fixed the rest of issues around precision agriculture are minor. The new ISO-BUS will help, but we have at least 10 years before that technology works its way through the industry.
Start making purchase decisions based on the quality of support you’ll get. The second best gear with the best support trumps the best gear if you can’t operate it.

We have come up with a few simple rules for Variable Rate Technology (VRT).

1. VRT pays when the yield difference between two zones is ~1 t/ha or more.
2. You need to know what is causing that variability. This is nothing but basic agronomy. What is the constraint? For farmers in Western Australia (home for me) it is often soil type which equals water holding capacity. But it could be compaction, subsoil toxicity, water logging, and the list goes on.
3. Can I fix the problem? Will amelioration remove the problem? If the answer is yes you are lucky, most problems can’t be fixed – just reduced.
4. Zones should be simple. Have only 2 or 3 zones and the location of the border should be “close enough is good enough”. If instrument that we measure with is 15m wide (header front) and the tool that we apply 18m (seeder bar) don’t worry if the boundary between zones is .5m this way or that way; think in seeder bar width.
5. The size of the paddock is less important, and zones don’t have to stay within a single paddock. I have seen growers zoning the farm (or all one crop within a farm) as a single paddock. Fences and roads are not issues. The part of the computer for auto steer is separate from the part that does VRT so as I put it, “You don’t have to colour inside the lines (paddock boundaries).”
6. Not all paddocks need PA. Just because you have the toys doesn’t mean you have to use them in every paddock.

Finally: There are lots of people out there selling information (imagery like EM, Gamma and NDVI), services (VRT maps and cleaning yield maps), and gear (guidance, task controllers, software packages and sensors). A word of warning; there are many fantastic people out there but a few bad ones are making it tough on the rest. You need to do your homework. Ask for references and good luck!

Dr Roger Mandel
Lecturer Agronomy, Curtin University of Technology