10 top tips: GPS kit

High-tech GPS equipment is a great way to save time, diesel, wearing metal and fertiliser, but you need to have a plan before you start buying the equipment.

That’s the view of consultant Robert Gazely, who helps advise on GPS matters across the 500,000 acres of farmland managed by Strutt and Parker.

“Farmers are taking the right initial steps to move towards precision farming, but they are sometimes not integrating that into their existing business,” he says. “It’s important to include precision farming equipment as part of your overall machinery replacement plan.”

Here are his top 10 tips to consider before you write out that big cheque:


Before you buy any new piece of equipment, check that it will be compatible with your other kit and with upcoming purchases, says Mr Gazely. So if you’re buying a new fertiliser spreader, check that it is Isobus-ready and will be compatible with your tractors. If it is, you may well be able to use your tractor’s existing screen with it, rather than buying a second one.

Check for auto-section cut-off

One of the best money-saving aspects of GPS kit is using auto-section cut-off on your sprayer and fertiliser spreader. If you plan to go down that path, check that any new machines you buy have that facility.

Ask the neighbours

Anyone with more than 500 acres of combinable crops should be able to justify a light bar unit in terms of better accuracy. Ask your neighbours how they are getting on with GPS.

Size matters

Match your kit to the size of your farm. It’s a far-from-exact science, but a lightbar that gives just guidance is ideal for anyone in the 500-1,000 acre band. If you’re bigger than that, an assisted-steer (using a motor to physically turn the steering wheel) or full autosteer (using the tractor’s steering rams to do the job) system is justified.

Match accuracy to kit

Match the accuracy of your kit to the size and type of farming you do. Standard DGPS is free to use and gives an accuracy of +/- 1m. Deere’s SF1 gives an accuracy of about +/- 30cm and is also free. Those are fine for cultivations.

Subscription services like Omnistar HP and Deere’s SF2 give +/- 5-10cm accuracy, cost £1,000-£1,500/yr and are good for drilling, mowing, combining. The kit can cost between £8,000 and £15,000, though.

For the full monty, ie an RTK accuracy of +/- 2.5cm, you’ll be paying £10,000-£17,000 for the hardware and installation and £1,000-£1,500 for the signal subscription. So you need to be sure you can justify that cost in terms of savings in fuel, fertiliser and time.

Use the information

If you’re producing yield maps, make sure you’re using the information gained. This could be by moving to variable-rate application on the fertiliser spreader or even variable-rate drilling (though that’s still in its infancy).


Be aware that your staff may need extra training for this kit. Also, think ahead – don’t go to the dealer in mid-July and expect him to be able to get in and fit the kit before harvest.

Replacement policy

Include GPS kit as part of your farm’s machinery replacement policy (if you have one). Strutt and Parker-managed farms have a five-year rolling replacement policy and GPS kit is included in that.


Don’t forget about installation time and cost. These can get forgotten when you’re focusing on equipment and subscription costs, but they can be substantial. Make sure, too, that tractors purchased are autosteer ready – you don’t want to be running wires all over the tractor. Don’t buy untested kit either (unless you’re an expert).

Transferability of kit

Think about the transferability of kit from tractor to tractor. This can be complicated, so talk to your dealer at the outset – most of the big ones now have a GPS specialist. Bear in mind, too, that a multi-make system may well give the best performance but could also be more complex to set up.


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