Thursday, 2 May 2013

Planting by Numbers

The next time you buy some oven chips, think about this : they were probably planted with the help of robots controlled from outer space. No, I've not gone mad, it's a fact.

On Monday evening I walked over to the fields to the west of Rake Lane because Richard Wainwright, the farm manager, had told me that they were starting to plant potatoes and there would be some big machines to see and photograph.

The first thing that caught my eye was a cluster of tractors and machines in the corner of the field and
a telehandler busily loading seed potatoes into a hopper on back of a tractor.


A Manitou telehandler loads seed potatoes for planting (click to enlarge)
But where was the robot?

Far off down the hill, there was a yellow tractor running on caterpillar tracks, it was dragging a large
cultivator and heaping the soil up into three huge ridges. Curiously it was cultivating every other row,
leaving a gap of uncultivated soil and then at the end of each row, turning back and cultivating the
clear strip.

CAT Challenger - precision ploughing (click to enlarge)

As I took photographs the tractor drove to the end of the row and stopped and the driver, a softly spoken young man called Carl got out.


CAT Challenger with GPS controlled steering (click to enlarge)

He explained that the tractor, a Cat Challenger, weighing over thirteen metric tonnes, was steered by a computer system that in turn figured out where it was using GPS (Global Positioning System).

So this was the robot.

GPS Relay (click to enlarge)

A relay station, on a tripod in the corner of the field, picks up the location signals from GPS satellites, orbiting the earth. These signals are relayed to a computer steering system in the cab, Carl then has to cultivate his first two swathes of earth and mark way points on them using the computer system.

Once this is done the computer knows where all the other furrow need to be cultivated and so it takes over and drives the tractor to replicate those first two swathes all over the field, the only intervention needed is to disengage the automatic steering at the end of the row, lift the cultivator and turn the tractor. Once the computer detects that the tractor is at the start of a new row it takes over again.

Carl explained that the system is accurate to within a few centimetres and so reliable that he could start the rows at random all over the field and they would match up perfectly without any gaps or overlaps.



Inside the CAT - lots of controls in the cab. No, I don't understand it either (click to enlarge)


Inside the CAT - rear view from the cab (click to enlarge)
But I was still confused about all the other equipment, so Richard explained the whole process to me. The objective of the exercise is to make ridges of stone-free and clod-free soil for planting potatoes, just as you'd want to do in your own potato patch at home.

The GPS tractor makes a first pass, cultivating the soil and heaping it up into large ridges. Then
tractors equipped with de-stoners lift the soil and riddle out the stones and clumps. The soil is deposited back to make a broad ridge of fine soil and the stones and clumps are dropped into the grooves between the ridges. When the de-stoners turn round and come back up the next row these stones will be squashed back into the soil by the tractors wheels so they can't damage the machinery when the potatoes are harvested.


Finally - a potato planter in action (click to enlarge)
Finally, the potatoes can be planted: another tractor runs down the ridges and inserts the potatoes along with suitable fertiliser and pesticides and reshapes the rows.

End of the day (click to enlarge)

By now the light was starting to fade and photography and potato planting was was becoming tricky. Carl had already driven the CAT off,  so I thanked Richard and headed back home, walking between rows of potatoes made by a robot controlled by satellites from outer space. Oven chips will never seem the same again.

Many thanks to Richard and Carl kindly for making the time to explain the basics of farming to your agriculturally clueless editor.

All material © Philip Stone 2013

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