It is a return to what used to work without chemicals: more and more farmers are turning to hoeing and harrowing – in order to save on pesticides and fertilizers or to do without them altogether. Because the prices for fertilizers have risen sharply. People have been hoeing and grooming for as long as agricultural technology has existed, says Tobias Weggel from the agricultural college in Bayreuth, Upper Franconia. “Now the topic is experiencing a renaissance.”
Mechanical weed control offers great potential for reducing the use of pesticides, according to the Leibniz Center for Agricultural Landscape Research (ZALF) in Müncheberg, east of Berlin. “For certain crops, wild herbs can also be controlled using mechanical methods, such as harrowing or hoeing,” says ZALF boss Frank Ewert.
The German Agricultural Society (DLG) also emphasizes that the topic of hoeing and harrowing has become more present in agricultural technology in recent years. The reasons for this are diverse: Social requirements and the rules derived from them “point the way away from chemical plant protection and towards mechanical processes,” says Roland Hörner, DLG department head for agricultural technology.
Organic farming in particular has always relied on mechanical control of weeds – pesticides are not allowed to be used here anyway. Now more and more conventional companies are showing interest in this variant. Because the chemically produced substances have become more expensive. The Russian war of aggression against Ukraine in particular caused fertilizer prices to rise extremely, so that agriculture is looking for alternatives. And the EU’s Green Deal is forcing the industry to save on pesticides.
Weggel therefore observes “dynamics in the market”. Many agricultural technology manufacturers are already active in this area. Five to six years ago, for example, the topic was mainly dealt with by smaller manufacturers. Large agricultural technology companies have now also joined in.
Mechanical processes release nutrients
But how exactly does hoeing and grooming work? When weeding, weeds are buried or pulled out. This technique is suitable for grain, corn, broad beans, peas, potatoes and some vegetables. The time range when harrowing makes sense is very limited. Because crusts in the soil are broken up, it is better ventilated and the crop can develop more quickly. When hoeing, the ground is opened up so that weeds are also removed. Mechanical processes also release nutrients into the soil. According to Weggel, the rule of thumb is: hoeing or grooming twice produces as much fertilizer as fertilizing once.
But the procedures don’t just have advantages. You have to go to the field more often. So more diesel is consumed, says Weggel. The investments in the technology are relatively high. And finally, mechanical weed control is very time-consuming. Hoeing and harrowing are considered the oldest forms of soil cultivation. But the technology is now modern. They rely on camera and satellite control. Many start-ups are active on the market. “It remains exciting, right up to the point of robotics.”
Centimeter-precise steering systems
The methods of mechanical weed control have been known for a long time, but have developed enormously technically, says DLG expert Hörner. “This is particularly true in the area of chipping technology, including chipping robots. Here, GPS-controlled, centimeter-accurate steering systems have revolutionized the process and compensated for a significant disadvantage of the past.” The shortage of active ingredients and agents in chemical plant protection also made the mechanical variant interesting. However, this variant of farming is not a panacea: the time required is significantly higher due to the more frequent journeys, as is the dependency on the weather. In addition, hoeing and grooming only help against weeds, says Hörner. Plant diseases and feeding pests still have to be combated differently. And: “Mechanical processes cause considerable damage to the ground fauna, especially ground-nesting birds.”
The Bavarian State Institute for Agriculture, for example, supports the topic scientifically. A long-term project is currently underway: “The aim is to be able to control weeds in arable farming with a significantly reduced use of herbicides and even to avoid the use of chemical-synthetic herbicides.”