The satellite-controlled tractor

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The satellite-controlled tractor
The satellite-controlled tractor

The Satellite Controlled Tractor

Scientists from the University of Gödöllö in Hungary are preparing a cooperation with the Institute for Soil Science and Soil Conservation at the University of Gießen for the application of the Global Positioning System (GPS). This is a satellite network originally developed once for military purposes. From April, under the direction of Prof. Dr. Tamás Harrach, test areas on two large Hungarian farms will be mapped and evaluated, one in the lowlands and one in a low mountain range. The aim is to create soil and soil function maps that reflect, for example, the soil water balance, nutrient supply and site-specific yield potential, and are the basis for the sensible use of satellite technology. The Global Positioning System (GPS) is arguably the military invention that has gained the most traction among civilians in recent years. If the US Department of Defense switched off its GPS satellites, large parts of our civilization would collapse: planes would no longer be able to find their runways, ships would no longer find their ports, transport companies would no longer be able to track their trucks. But what could GPS be used for in agriculture? After all, a farmer should know where his field is.

There are currently 25 GPS satellites orbiting the earth at an altitude of 20,000 kilometers. At any point in time there are at least three of them above the horizon from which a time signal can be received. The rest is simple trigonometry: from the satellite position and the propagation time of the signal, a GPS receiver uses the part of the signal released for civilian purposes to calculate its own position with an accuracy of around a hundred meters. That may be enough to bring a ship safely across the Atlantic, but GPS only becomes interesting for agriculture when the position can be determined with an accuracy of one to five meters, a feat that is actually reserved for the military part of GPS. This can also be managed with the help of a correction signal from a radio station.

Possible applications of GPS technology for agriculture are being researched at the Institutes for Agricultural Business Management and for Soil Science and Soil Conservation at the University of Giessen. A first step is to equip a combine harvester with a GPS receiver. It uses it to determine its position every second and saves the data together with the amount of grain harvested. A yield map is produced from the mown field, which makes it clear that the grain does not grow evenly at all. On a test area in Münsterland, for example, the yield on different sub-areas of the same field can vary between four and eight tons of wheat per hectare - even though it has been farmed evenly.

The changing yield is due to different soil structure, groundwater levels and nutrient supply, although the field looks the same on the surface. Determining the respective causes for the different yields is a task for soil science. For this reason, soil samples are taken from as many areas of the field as possible, and their exact position is also measured with a GPS receiver. The soil data can be combined with the yield map and other data such as the weather in a geographic information system.

The goal of all the effort are so-called application maps: Up to now, if a farmer wanted to sow, fertilize or apply pesticides, he set a fixed dosage on his device with which the entire field was cultivated. Now the tractor is also equipped with a GPS receiver, which, for example, controls the amount of fertilizer spread. Dipl.-Ing. agr. Kai-Uwe Ostheim from the Institute for Agricultural Business Studies does not believe that yields can be increased significantly in Germany with the new technology. He sees the economic advantage in the savings potential if the entire field is no longer fertilized, sown and sprayed to the maximum. Savings in operating resources also mean improved environmental protection, because there is no longer a risk of unnecessary fertilizers or pesticides getting into the groundwater. This paves the way to site-adapted agriculture.

As an economist, Kai-Uwe Ostheim naturally does not believe that everything that is technically feasible is also economically sensible. In his doctoral thesis, together with the Raiffeisen-Zentralgenossenschaft Münster, he is trying to find out whether the new technology pays off. Above all, the "learning costs" quickly throw a spanner in the works.

With all due caution, he says that farms with a size of 150 hectares or more, as is the case in eastern and northern Germany, can use GPS technology sensibly. And of course, regardless of the size of the business, it is worthwhile for machine rings and contractors who use their agricultural machinery on behalf of farmers. GPS is predestined for the large farms that characterize Hungarian agriculture, although in certain cases yield increases could also be expected.

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