By CHARLIE BURTON, 17 Nov 2010

Smartphone-controlled tractors that steer themselves via GPS. Intelligent sensors that know precisely how much fertiliser to spray. Precision agriculture lets farmers tame nature with data — thus boosting their crops

it’s a sun-soaked August afternoon in Geneseo, Iowa, and Clay Mitchell is driving his crop sprayer down a poker-straight road that parts the emerald landscape. Butterflies dance above the prairies, while the crickets chirp below, their song lost to the engine’s roar. He turns the machine left into a field of soya beans and brings it to a halt. In a few weeks the plants will be golden-brown, ready for harvest — this is their last chemical hit of the season. Mitchell presses a button on top of the joystick-like accelerator to his right. Two arms fling out from the rear of the vehicle, unfolding to create an 18-metre boom. He grasps the stick and, as he pushes it forwards, the eight-tonne machine starts to move between the stalks. He lifts his other hand from the wheel: he need no longer touch it. The sprayer is steering itself.

Using hyper-specific GPS and a digital map of the field to maintain pinpoint accuracy, it forges straight ahead, squirting out pesticide. The autopilot not only saves fuel by eliminating driver error but also remembers where it has been. So, on the sprayer’s second pass, the right-most nozzles automatically click off and on to prevent double-dosing plants that have already been covered. “The inside backed over itself a little bit,” explains Mitchell.

This is no off-the-forecourt kit. Mitchell, a Tiggerish 37-year old with intense blue-grey eyes set beneath wavy copper-coloured hair, has been adapting the John Deere machine since he bought it in 1998. Most recently he stripped out the nozzles, replacing each one with a set of three to release liquid at different rates. Now, when he speeds up or slows down, the vehicle can switch nozzles rather than alter spray-pressure as it used to. This seemingly unremarkable change has important consequences: the droplets maintain an optimum size, coating leaves more effectively and keeping the chemical within the field. “Environmentally, drift is a big issue,” he says. “If the entire outside edge of the field gets a sub-lethal amount, then it’s a sure thing that it’s only going to take a couple of years for some weeds to develop resistance.”

And when Mitchell twists the tractor around at the field boundary, a potentiometer determines the relative velocity of each side of the boom and instantly varies the rate to stop it underdosing the outside of its turning circle, or overdosing the inside and killing the plants. “All at once, we save 30 per cent,”

Mitchell says. “This is the best technology that we have ever come up with. It’s just extraordinary.” According to Purdue University, the average farmer is going to lose $30 [£20] per hectare this year, but it’s going to be a decent harvest for Mitchell. And this kind of cost cutting innovation has been critical.

Welcome to precision agriculture. Since 10,000BC, people have grown crops using trial and error, received wisdom and how the soil feels when they rub it between their fingers. Yes, mechanisation furnished the Western countryside with seed drills and threshing machines in the 18th century, and later replaced horses with tractors. But these were blunt tools that just did more, faster. This new precision trend, based on satellite positioning, aims to sharpen them with data: to squeeze costs — seed, chemical, fertiliser — and control nature’s imponderables. Although Mitchell is something of a trailblazer, he’s the last person you might expect to be a farmer.

A Harvard biomedical-engineering major, married to a civil-rights lawyer whom he met at university, his social life is largely on the East Coast. He has few friends in Iowa, and when not looking after the accounts of the local church, where he was baptised and married, he spends his free time on jet boats or mountaineering. If he were not working the land, he jokes, he’d be a supermodel.

But the earth is in his blood. Since the Mitchells first arrived from Ireland in the 1870s, five generations of the family have farmed around Geneseo Township, which has a population of 1,206. It sits 225km south of Minneapolis and life there is set to the rhythm of the seasons and the church calendar. The roads didn’t have names until 16 years ago. Still, the place is industrious: Iowa produces 19 per cent of the United States’ corn, and the local John Deere foundry is often described as the largest tractor factory in the world. That’s where Mitchell’s father honed his engineering skills, working night shifts after full days on the farm. “Sometimes he’d only sleep for an hour,” he says. “The Midwest work ethic is strong in this area. My dad’s dad, especially, would always ask me, ‘Are you a hard worker? Are you a hard worker?’ as I grew up, every day when I saw him.”

When Mitchell was a young boy, he helped his father build much of the equipment still in use on their 1,000-hectare farm. Take the system of vast grain bins, where the harvest is moved from driers into storage by rotating screws: much of it is made from recycled machine parts. Then there’s the bins’ blue control panel in the adjacent shed, which is decorated with round lights coloured like boiled sweets. “We wired all of these buttons, inputs and outputs,” he says. “Dad would give me ten cents for every relay I’d wire up.”

Now, Mitchell can operate the panel from his Android phone (he can adjust the sprayer’s settings in the same way, too).

His aptitude won him his place at Harvard, and he bought 80 hectares of farmland back home during the third year of his course.

After a brief spell at the news website AgWeb, he returned to Geneseo in 2000. “Farming is just such a stable lifestyle,” he says. “The joy of it is very linear with yield, and there’s nothing more productive than corn. I mean, it’s just glorious and huge.

It’s a visceral pleasure, harvesting a crop and watching the grain flow and all of that.” Compared to other farmers, though, his pursuit of this bounty takes an exceptional form. “If you were to figure out how much of our research is being applied by farmers, it’s a low percentage,” says Tony Grift, an agricultural and biological-engineering professor at the University of Illinois. “But when I saw Clay I was like, ‘Holy cannoli, this guy does the real thing’. He is probably the most progressive crop farmer that we have here in America.” Underpinning precision farming is satellite navigation. It is at its most effective when bolstered by real-time kinematics (RTK), which takes the standard positioning signal used by a car’s satnav — accurate to about three metres — and makes it true to within 2.5cm. First, a fixed GPS receiver is installed on the land and programmed with its own longitude and latitude. This base station looks at the co-ordinates it is sent from the satellite, compares them to its real position and calculates the discrepancy. Using radio transmitters, it immediately broadcasts a correction signal to other farm vehicles’ satnavs so that they can account for the (always changing) error on the fly.

Mitchell thinks he was the first grain farmer in the US to adopt RTK — he introduced it to the family homestead in autumn 2000, to fine-tune where he grew individual plants. Rather than wastefully

spreading fertiliser all over the surface of the field, Mitchell knew there were monumental yield gains and cost savings up for grabs if he could inject the soil with fertiliser in rows, and then come back months later to place a seed exactly on top of each granule.

No bulletproof methods existed, so he decided to crack the problem himself.

He tinkered with lasers and cameras, before reading about RTK in a farming magazine. A satellite positioning firm, Trimble, was developing it for horticulture. He asked Trimble to subsidise his installation but it had not considered the use that Mitchell was suggesting, and though he was a time-waster. Eventually it played ball in return for a report in Farm Journal, whose backing Mitchell had already secured. He quickly overhauled his tractor with RTK autosteering and then kitted out the attachable seeders and fertiliser machines with it too. This meant that undulations in the field couldn’t drag the whole set-up off course. He then created a system to remember exactly where the fertiliser granules were so that seeds could later be planted in the same places. “Using RTK was an awesome way to do it,” he says proudly. It has been key to his farm ever since, not least to ensure the machinery drives only over the same strips of earth. This “controlled traffic” approach frees up the rest of the soil, making it more fertile.

To do even better he is working with John Deere, which funds many of his experiments — such as that with the sprayer — to discover the optimum distance for placing a granule of nitrogen from the seed after sowing (using another machine, called a “side dresser”).

Sitting at the back of the barn that doubles-up as his office and workshop, its walls lined with neatly labelled shelves (“automotive wire”, “air tools”), its scent a mix of metal filings and oil, Mitchell takes a slug from a can of Red Bull, boots up his PC, and lays out the plan. A map on his computer shows colour coded crops. Each colour represents plants with nitrogen placed at a different distance from the seed: zero, 12 and 25cm. He might be using John Deere’s kit throughout the trial, but he has already built his own side dresser “at a sixth of the cost”. His hunch is that 12cm from the seed will be the best distance. But the proof will be in the harvest.

Ask most well-informed farmers what precision agriculture means and they will most likely mention the phrase “variable rate”. This has become a buzzword to describe the application of fertiliser or seed, say, according to exact variations in plant growth, or soil nutrients and type. But Mitchell scorns it. “When people do a research report on the benefits, the story always comes out really good, but it’s very often invented.” For one, ground conditions are often weather-dependent, leading to muddled results. Also, the machinery isn’t as reliable as its marketing makes out. But, more importantly, he says, there are bigger things to worry about: “I’m not saying it’s voodoo or a scam — it’s a story those people really believe after working on it quite a bit. What I’m saying is it’s niche. It’s a smallish issue and most farmers are in a situation where other things are more important.” He much prefers a brute-force approach.

Take poor soil. Mitchell’s reaction is not to use less fertiliser on arid land — the “variable” school’s thinking — but to move the good earth to where it is needed. He’s recently done just that for a patch that fell victim to soil erosion. “We tend to lose about four tonnes of soil per hectare per year down the Mississippi river. Louisiana is Iowa soil,” he says. His machines used lasers to ensure they scooped up the exact right amount, and then autosteered with RTK via the most efficient route to the drop off point. The farm’s motto is “Farming the Way Nature Intended”.

Mitchell says it’s ironic. In Europe, variable rate is a big deal. “Over there you had Romanticism,” he says. If you believe that God is interfused with the world, “you’re reluctant to push Mother Nature over”. And where there are caps on chemical usage, he concedes, the tech becomes more compelling. “Where you have an actual limit, hell, you gotta do everything you can.”

Mitchell’s main motivation is profit and his drive borders on the obsessive. “At the end of your life there’s a path you’ve gone down, there’s one branch you’ve taken to the end and that’s it, you’re done,” he says. This year he expects to reap 750 bushels a hectare; a hundred years ago, the average for the region was just 75.

Perhaps that’s why over 500 farmers have come to see Mitchell’s innovations: some from the US and Canada; others from Europe and Russia; and still more from as far afield as Africa, China and Australia. So many, in fact, that it’s become a problem — he no longer puts his address online for fear of surprise visitors (once a group of French agriculturalists flew in unannounced and stayed for three days). One who went through proper channels was a 39-year-old Yorkshireman, Clive Blacker.

Ten kilometres north-west from York city centre lies Church Farm, Blacker’s 240- hectare arable enterprise, which has been in his family since the 30s and extends out from behind a wide street of mixed-period houses. Six years ago Blacker travelled the world on a Nuffield Farming Scholarship, an award devised by Lord Nuffield in 1947 to improve UK agriculture through overseas research. On Blacker’s four-week tour, he stopped by the Mitchell farm. “Clay was inspirational,” he says. “He shouldn’t be in agriculture, he’s too clever.” Blacker brought back innovations such as transmitting data between vehicle and office using wireless internet, and has committed further to precision farming. But unlike Mitchell, he has decided to practise variable rate.

In July, Church Farm’s grain stores were swept out in time for the new crop, and the rituals of harvest began. But this year something new happened: the combine harvester was fitted with RTK.

Now it is mid-August and Blacker is watching it churn through a field of oilseed rape, leaving a mat of jagged straw and a smell like cut grass in its wake. Standing windswept on the field, in his workaday uniform of a short-sleeved shirt and thick-knotted tie, he has a schoolboyish appearance that doesn’t telegraph the scale of his ambition. But not only does the combine steer itself all the way, it also — crucially — produces a yield map of grain collected at different points. Blacker will compare this to maps of soil type and chemistry to explain the variations. Next season he will give this data to other machines so that they can variably distribute fertiliser and seed in response.

He disagrees with Mitchell that it’s a worthless endeavour. For centuries the land he now owns was a series of little fields, all farmed differently. That has affected the soil so much that, without variable rate, Blacker says, the farm would be less profitable. He likens it to restoring the hedgerow boundaries of those old fields virtually. British farmers are starting to make the jump to precision agriculture — according to a 2009 survey, 13 per cent have switched to autosteering — as a new generation takes over and market conditions toughen. Blacker is one of those early adopters. “My mother was a computer teacher, so it came naturally,” he says. “I’ve always believed that if a computer can do something then it’ll do it better than you can.”

The jewel in his crown is the N Sensor, a product that Blacker helped develop in 2001 in partnership with its manufacturer, Yara.

It resembles a large telephone, strapped to the top of a tractor, and moves through the field while shooting infrared light at the plants and analysing the wavelengths that reflect back to discern the amount of nitrogen in the leaves. Its computer then tells the fertiliser spreader trailing behind it to deliver a specific measure. “Every drop goes where it is needed,” Blacker says. “The N Sensor makes a decision in the field on the day you’re doing it.”

Three years ago the British Sugar plant in York closed, ending 80 years of refining. As a sugar-beet grower, Blacker was hit badly. “The factory was a third of our business, and the market deteriorated overnight,” he says. But precision tech, such as the N Sensor, had made the farm better placed to take the knock.

Some farmers — including Mitchell — are sceptical. They say the assumptions are too easy: a yellow crop doesn’t always indicate deficiency. But Blacker is bullish about its worth. The results of his first trial bowled him over. “The N Sensor put on half the amount of nitrogen, but the crop out-yielded me half a tonne.”Many of his contract-farming clients asked to use it on their land too, so he setup Precision Decisions in 2004 to sell it alongside other services. He now maintains about 215 N Sensors in the UK.

From Mitchell’s seed fertiliser aligning to Blacker’s variable rate applications, precision farming seeks to magnify profits. But it’s not just good for the balance sheet, it’s good for the nation, too. Andrew Clark, the National Farmers’ Union’s head of policy, says the UK’s food security situation is pressing. “Agriculture is in the doldrums,” he says. “Wheat productivity is pretty much flatlining, certainly in this part of Europe, and climate change is going to favour north-western Europe where there are technologically literate farms. Precision tools are absolutely critical.” They’re also, he continues, a boon for the environment because they minimise runoff into adjacent habitats. And in areas where legislation restricts farmers — nitrogen-vulnerable zones, for instance, where nitrogen application is limited — this technology can help turn a healthy profit. That’s why the NFU wants the government to help to develop precision equipment through universities and manufacturers.

So it’s timely that a German company, Claas, is setting up RTK base stations to cover the UK. Farmers will be able to subscribe to Claas’s correction broadcasts, just as they would to a mobile network, rather than have the expense and complexity of building a private RTK system. “We started in the east of England — where the majority of our customers are — but we aren’t stopping there,” says Edward Miller, Claas’s product specialist. “If everything goes to plan, within the next couple of years the majority of arable farmland in England will be covered.” Claas has 100 customers so far, and Miller says demand is on the up. “It’s a steep curve: a few years back at farm and agriculture shows you’d be hard pushed to find people to talk to about precision farming. Today, you’re hard pushed to find five minutes for a cup of coffee in between talking to people about it.”

Claas is betting hard that RTK will become ubiquitous. If it does, what happens when operators get bored of manning self-steering vehicles? “Robots,” says Simon Blackmore, MD of Unibots, which researches intelligent agricultural machines. “I don’t see any real impediment in these things apart from safety and reliability,” he says. “You train a farmer how to use a robot and the first thing he’ll do is set it up, walk away and let it run. When that goes wrong it could be life-threatening.” But if this could be overcome, the benefits would be huge. “I walk across the fields every morning, and I see half of each one should be harvested now. The plants are starting to fall over but the other half of the field is not ready yet.” A selective harvester robot would be a solution. Another useful device, he says, would be one that seeks out and destroys weeds.

He’s built prototypes but says he is having difficulty getting them to market because, paradoxically, none of the major companies is producing anything similar. “But when commercial robots appear, everybody’s going to want one.”

What Clay Mitchell can’t buy, he builds. This winter he plans to start work on a robot that locates weeds by detecting their colour prior to sowing. “Normally you spray every square centimetre of the whole field. Here it’s only turning on and spraying a patch where there’s something green: perfect for a small machine. I would set it up with a small amount of chemical and send it out. It would go out all day long, back and forth, and cover a field and I can retrieve it at the end of the day. It’s really something I should do.” But for now there’s welding to be done on the grain bins to prepare them for what he hopes will be a record haul come harvest.

It’s 32°C outside. It’s a good day for growing corn