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Smart Tractors: Improving Crop Yields One Plant at a Time

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It used to be that farmers were concerned about the health of their fields as a whole. New technologies now enable them to care for plants on an individual basis. From fighting fungus to adjusting soil acidity, smart tractors can do it all.

Farmer Manfred Hurtz still drives his combine harvester to the edge of the field himself, but then he switches it to autopilot. An electric motor on the steering column guides the Claas Lexion through the wheat fields, and the guidance system can even receive its commands through GPS. "It enables me to keep my rows straight, down to the last centimeter," Hurtz says proudly.

The high-tech farming machine doesn't just harvest grain. It also collects data. When he returns to his office later on, Hurtz will switch on his computer and prepare a so-called yield map, a grid of his land that tells him exactly how much grain he harvested from each sector of his field.

The farmer from Nideggen, in the western German state of North Rhine-Westphalia, wants to extract as many secrets as possible from his fields. The quality of the soil on the north slopes of the Eifel Mountains varies widely: The earth fluctuates from sandy loam to loamy sand to shell limestone, while soil density, nutrient content and water retention capacity can vary every few meters.

"In the past, we were constantly adjusting the fertilizer sprayers by hand," Hurtz recalls. When he drives into the fields to apply fertilizer today, his tractor looks as if a Smurf-blue surfboard were tied to its roof. In reality, the tractor is carrying a mobile metering device on board. The so-called N-sensor (nitrogen sensor) measures the nutrient content of the plants and quickly calculates how much fertilizer they need. Then the sprayer on the back of the tractor sprays the correct dose of nitrogen fertilizer onto each segment of the field. This saves costs and reduces the environmental impact.

Scanning for Weeds

Only a few years ago Hurtz, a technology buff, was seen as an oddball in his town. But now navigation systems have arrived on Germany's farms. A neighbor recently bought Hurtz's old GPS device. The German Agricultural Society estimates that 10 to 15 percent of farmers now apply various methods of "Precision Farming" (PF).

"For a long time, farmers lacked the tools to precisely control their resources," explains Roland Gerhards of the University of Hohenheim. "Fertilizer and pesticides were simply applied on a large scale, ignoring the differences in the soil and crops." At the university's test farm, Gerhards and his team are now experimenting with sensors that detect weeds and can even gauge the health and nutrient requirements of individual plants.

The agricultural researchers have outfitted a field vehicle with a GPS receiver, a computer, a spectrometer, an infrared camera and fluorescence measuring devices. A colorful jumble of cables in the foot well leads to the computer. When the Hohenheim "Sensicle" rolls across the fields, it gathers data on the light reflection of the soil and vegetation, determines the chlorophyll content of the plants based on fluorescent properties and scans weeds with a camera.

If thistles appear on the screen, for example, a nozzle for the appropriate pesticide opens in the attached spraying cart. Using the same principle, the smart tractor can also determine the fertilizer requirements or diseases of individual plants in real time and react accordingly. The Hohenheim researchers' goal is to develop a sensor platform -- a mobile green thumb -- that a farmer can mount on his tractor.

'Bonirob' the Field Robot

"The new methods bring farming and biology closer together," says Peter Leithold, managing director of Agri Con, a company in Ostrau in the eastern state of Saxony. The company sells sensors and teaches farmers how to use them, but it also develops its own intelligent farming strategies. Scientists at Agri Con are currently testing an artificial nose that can sniff out antibodies of plants with fungal infestation. If the sensor detects fungi, a fungicide is automatically sprayed onto the plants.

The Precision Farming sector has long been an important field for major producers of farming machinery. German tractor maker Claas, for example, now sells its high-tech products through a subsidiary, and US manufacturer Deere & Company launched a European innovation center staffed with 90 scientists in the southwestern city of Kaiserslautern in June. "This was something for visionaries at first, but now it's becoming more widespread," says Jens Möller of Claas Agrosystems.

The industry is pinning its hopes on real-time systems, in particular. Dieter Trautz, a plant expert at the Osnabrück University of Applied Sciences, is developing a soil sensor that can measure the pH value and simultaneously take the correct action, such as adding lime to overly acidic soil. This would eliminate the need to send soil samples to the laboratory. Trautz's machine consists of a cone that burrows into the topsoil and presses its samples directly against two sensors.

Another innovation in development at Osnabrück is "Bonirob," an unmanned field robot that takes a regular inventory of crops in the field, determining whether plants have grown since the last time the robot passed by, and whether the leaves are green or perhaps wilted. "In the past, you always considered the field as a whole in agriculture," says researcher Trautz, "but in modern cultivation it's the individual plant that counts."

Translated from the German by Christopher Sultan

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