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22.02.2019 - Anne Ehnts (Send email to Anne Ehnts)

Sustainable crop protection with the N-Sensor

Eric and Moritz Krull are farmers with abandon. At the beginning of January, they stand on the field in snowy rains and icy winds and inspect the autumn seeds. In a good four months' time, winter wheat will be in development stage 32, the right time for the first fungal treatment. This, however, will be different from that of most professional colleagues, namely variable instead of consistent.


For almost 20 years, Krulls have no longer farmed their land according to the watering can principle. The magic word is sub-area-specific. Their tool is a plant sensor, the Yara N-Sensor®. First they used it for fertilizing, then for growth regulators and for six years now also for plant protection with fungicides. Together with companies from Great Britain and France, they also took part in a field trial on variable application.

"In the end, it's not always about too much, it's about too little. In the public debate on chemical crop protection, this is often neglected," says Eric Krull. Of course, he is interested in his own company's success. But environmental protection and social acceptance are no less important to him.

In view of the backlog in approvals and the decline in sales of crop protection products, these are also the topics that are driving crop protection product manufacturers to support trials of this method. Dr. Helmut Schramm, President of the German Agricultural Industry Association (IVA), sees chemical crop protection facing fundamental changes: "It will soon be taken for granted that digital tools will help in deciding whether and how a crop protection product is to be used."

Prof. Jens Karl Wegener, head of the Institute for Application Technology in Plant Protection at the Julius Kühn Institute (JKI), estimates this similarly: "I can't deny that the future will bring digital solutions that take the regulations of agent application into account in order to use the correct and allowed amount. We basically have this already, for example with drift-reducing jets, where the use of a specific agent is tied to specific nozzle technology."

The weeds are still a problem

The industry is working flat out on digital solutions. "These days the goal is no longer to distribute crop protection products as evenly as possible over the entire target area. Future devices will support users with technical assistance, networking and sensor technology. In this way, pesticides can be saved, applied in a more targeted manner and application regulations automatically adhered to," says Wegener. One of his research projects also focuses on specific weed control using direct feed. The aim is no longer to treat the entire field curatively against a weed mix, but only to spray where there is weed and with the right product. "In the field, so far tank mixes are often used. A sprayer with direct injection is therefore required for the site-specific application of individual agents. The agent and water are carried in separate containers, mixed immediately before application and dosed in real time," says Wegener.

Together with the company Dammann, JKI presented a prototype of such a field sprayer at the last Agritechnica. While the spraying technology is already working, there is still a problem with real-time weed detection. A whole series of research teams are looking for practical solutions. But back to the fungicides and the everyday life of the Krulls in Mammendorf, a small village just outside Magdeburg.


In a nutschell

  • Eric Krull is convinced of the sensor-assisted application of liquid fertilizers, growth regulators and fungicides.
  • The inputs are variably dosed, depending on the amount of biomass.
  • This ensures yields, reduces the use of fertilizers and pesticides, protects the environment and saves money.

Their site-specific plant protection is based on the idea that no plant population grows homogeneously. Depending on soil characteristics and growth conditions, the amount of biomass in a wheat crop varies by a factor of six over small areas."Between GS stages 32 and 39, when brown rust and mildew cause us problems, the biomass fluctuates between 2 and 5 kg/m². If I apply the same amount of fungicide everywhere, I will overdose in the range of 5 kg/m² either under or in the range of 2 kg/m². Neither is good. The overdosage harms the environment and costs unnecessary money. Underdosing can cost yield and increase resistance." The plant manager brings it to the point: More biomass, larger spray surface - less biomass, smaller spray surface. An adult needs nevertheless also a higher dose of a medicine than a small child. Otherwise it won't work or won't work long enough."

This is how the N-Sensor works in crop protection

For the whole thing to work, you need sophisticated hardware and software. Father and son take the Massey Ferguson out of the hangar and attach their crop protection sprayer, an Amazone UX 6200 with 36 m working width. On the tractor roof there is a grey box, the N-Sensor. It is connected to the GPS system of the automatic steering system in order to record data for later documentation. The tractor, trailed sprayer, GPS system and sensor communicate with each other via ISOBUS.

The sensor uses simple physical effects: Depending on the chlorophyll content and amount of biomass, a plant population reflects light to different degrees. The N-Sensor measures the reflected light and uses it to calculate the N uptake of the plants to date. This value is the data basis for the site-specific application, whether liquid fertilizer, growth regulator or fungicide. If the value is high, a lot of chlorophyll is present, i.e. biomass. Then the N quantity must be reduced to GS 32 in order to avoid lodging. On the other hand, the amount of growth regulator or fungicide, must be increased because the spray area is larger. Using stored control curves, the computer determines the required quantity
of the operating material in real time, transmits the data to the sprayer and applies.

No more "too much" with growth regulators

While Eric Krull's main concern with fungicides is not to underdose in dense grain stands, he does not want to overdose when using growth regulators. "Unfortunately, we used to do that. We wanted to be on the safe side so that nothing would go into lodging. Today I know better. Too much growth regulator shortens the roots and can reduce the yield during drought. Many years of our own trials have confirmed that by using these preparations variably we have always reduced the overall application rate, benefited from increased yields at the same time and no longer had any problems with stored grain. On average over the years we have earned 40 Euro/ha more with the variable application of growth regulators".


The field sprayer of the Krulls has a GPS single nozzle switch. In combination with the N-Sensor, however, it is not used, so that the pitch length, but not the width, is worked on a sub-area-specific basis.

The technology ensemble is controlled via a terminal in the tractor cab. This is where Moritz sits and works through the "Precision Farming Box - Fungicides" software, which his father sends over online. "I got myself into it. But the operation is too complex for temporary staff," says Krull Junior. His father confirms that. He works in the office with the data management system agriPORT, which needs to be fed with information on impact, agent, water quantity and application rate. Eric Krull urgently wants better compatibility with his yield charts. Otherwise, the advantages outweigh the disadvantages.

"I only buy half of the agents I used to buy. I also kissed reduced expenditure quantities goodbye. With those we farmers have caused some of the resistance ourselves, not because we have underdosed overall, but because we have underdosed thick stands. When there is massive disease, the same amount of active ingredient is consumed faster in thick stands than in thin ones. In addition each passage costs me 11 to 12 Euro/ha. In the end, I save money," says farmer Krull. This is also supported by research results according to which sensor-assisted fungicide application in winter wheat is expected to save a total of 33 euro/ha - 12 percent less fungicides and 1.7 percent more yield with a comparable incidence of disease.

The bottom line is that the N-Sensor is a gain. "The technology is not in vain at around 20,000 euros and requires know-how and support that should not be underestimated, but the advantages outweigh the disadvantages. We are much more efficient in crop production today and work more sustainably and environmentally friendly than in the past," says Eric Krull.


This article was published in the current issue of Agrarheute (3/2019).


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