Growing a narrow range of crops on German farms does not necessarily meet with the goals of sustainable farming. Existing management conventions therefore may require a major rethink. Farmers are dealing with the consequences of this limited cropping by having to adopt new cultivation techniques or increase their use of crop protection products, but these problems could also be addressed by introducing new rotations that employ a greater number of different crops. This year's DLG-Feldtage exhibition, taking place this year at the DLG's International Crop Production Centre (IPZ) at Bernburg, Saxony-Anhalt, from 12 to 14 June, will give arable farmers the opportunity to discuss the options with agronomy specialists that understand the challenges and are looking for solutions.

The topic is particularly relevant because the IPZ at adjacent fields to where the DLG Feldtage is held, is currently conducting a long-term crop rotation trial that aims to produce recommendations for arable farmers. Different combinations of maize, wheat, sugar beet, triticale, durum wheat, peas and oilseed rape are being cultivated in rotation for a period of at least 12 years. This makes the trial one of the most comprehensive ever conducted in Germany, and the different rotations will be judged in terms of improved yield stability, plant health and soil fertility.

The trial, which was set up five years ago, aims to provide clarification on four key questions:

• Which crop rotation will achieve the highest financial margin at the IPZ site while maintaining the soil humus balance?
• Which crop rotation will produce the most stable earnings level at the site by providing a low-risk approach with minimal fluctuations?
• How do the crop rotations compare with regards to stability of yield and the quality of wheat produced? And
• How does sugar beet and oilseed rape performance compares in different crop rotations, particularly where they are both included in the same rotation and where they appear separately.

The head of the IPZ, Dr. Klaus Erdle, said it was important to allocate a lot of time to a project like this because of the complex mechanisms within the soil and crop system. “We are looking at the interplay between different crops and the effect that has on yields, crop health and even soil fertility,” he added.

The DLG also addressed crop rotation issue at its Winter Conference earlier this year, where the society's committees for crop protection and agriculture arranged a series of presentations on crop rotation. Opening proceedings, Prof. Dr. Bernhard C. Schäfer from the South Westphalia University of Applied Sciences, at Soest, quoted an excerpt from the DLG publication “Agriculture 2030” that stated: “Traditional agricultural principles in crop rotation design, soil tillage, sowing techniques and sowing times must once again find their way into good professional practice. The marketable spectrum of cultivable crops should be expanded so that classical crop rotation systems return a holistic aspect to agricultural production.”

Speaking at the DLG Winter Conference, Dr. Stephan Deike, from the consulting firm Acker- und Pflanzenbau der Landberatung GmbH, said that since the acreage of winter wheat grown in the country had broken through the three-million-hectare threshold, far greater fluctuations in yield had been noted across the country. The reasons for this, he said, were sub-optimal sowing times, unfavorable crop rotations and poor forage crops. Winter wheat was often grown on marginal sites, and if farmers deviated from the optimal sowing date and proven crop rotations, yield fluctuations were inevitable. The weaker the location was, the more important these factors became in growing a successful crop.

In the search for alternative crops for farmers to add into their rotation, Dr. Deike said exchanging land with potato or vegetable growers was an option, or they could grow legumes or grasses, as well as consider the contract cultivation of special and niche crops. However, he warned, alternative crops could be associated with challenges such as large fluctuations in yield and prices, as well as high costs for machinery, labor and advice. Two distinct business types could be identified Dr Deike suggested: large, well-established companies that often used niche crops; and others that did not want to get bogged down and focused on only a few crops such as wheat, oilseed rape and corn.

Dr. Deike's conclusion was that established cultivation systems were vulnerable to external influences, with weather fluctuations in particular, and the increasing development of resistance and restrictions in the use of pesticides and fertilizers could result in negative effects. The search for alternative crops was usually difficult, because not only might cultivation methods have to be changed, but new problems with fieldwork and business efficiency could occur. He advocated that the measures taken had to be adjusted to match the intensity of the problem a farmer faced. And early countermeasures were advisable, because once a massive problems has arisen, they could only be rectified through intensive countermeasures taking a longer period of time.

Prof. Dr. Enno Bahrs, from the Institute of Farm Management at the University of Hohenheim, presented five theses on the future development of crop rotations in Germany. His first stated that crop rotations will continue to grow. The professor's reasoning included the phytosanitary conditions, for example increasing resistance or more restricted availability of crop protection products, as well as Germany's new Fertilizer Ordinance and other social framework conditions, in conjunction with support programs, that might favor increasing crop rotations.

Crop rotations becoming more individualized or location-adapted, was the second thesis. Here, Prof. Bahrs said different points had to be considered. This included an honest, individual identification of the scarce factors of soil, labor and capital and their evaluation. In addition, it was about appropriate forecasting of future yields depending on the crop rotation. At the same time, future disadvantages from continuing with tight crop rotations, for example structural damage to the soil, additional costs resulting from increased plant protection and future shortfall in yields, had to be appropriately discounted. According to the professor's third thesis, crop rotations would become even more technologically determined and even more knowledge-based in the future. A growing range of technological tools will create different possibilities depending on the location characteristics, he said, and advances in plant breeding may also offer farmers a much broader range of cropping options in future.

Prof. Bahrs' fourth thesis stated that crop rotations would become even more "aesthetic". This would play a significant role in affluent societies, he said, pointing to the example of “Contour Farming”. Such a solution would play an increasingly important role in hilly and mountainous landscapes in future, the professor added, suggesting that there may also be a greater willingness to pay farmers for such measures.

The final thesis from Prof. Bahr was that large-scale recommendations for crop rotations were more challenging. This was because they all had to be adapted to local conditions, and when fewer possibilities for chemical plant protection were available, a farmer would have to act based on the location and operating structure of his business.

Farmer Doreen Riske who, together with co-owners, manages Agrar GbR Groß Kiesow, a 2,048-hectare arable farm in Mecklenburg-Vorpommern, gave the DLG's Winter Conference examples where the farm had to reconsider its crop rotation and the solutions it came up with. She explained that there had been considerable rotation problems in oilseed rape due to clubroot and crop pests, and in winter wheat due to field foxtail. Static surveys in oilseed rape, for example, showed that areas with a high-volume of insect pests resulted in three extra spray applications and higher insecticide costs than where pests were present in low-volumes.

Results like these were the catalyst for the farm to change its crop rotation. Agrar GbR Groß Kiesow had reduced the acreage of oilseed rape and winter wheat by seven and 10 percent respectively during the past 12 years, and additional crops of peas, maize, spring wheat and oats had been added. A comparison of the production costs and the proceeds from the individual crops showed it was possible to do well with this type of crop rotation, even in difficult years.

Ms Riske affirmed that problems could be solved through crop rotation. For example, the phytosanitary burden was significantly lower with a wide crop rotation in oilseed rape. Also, the farm was anxious to grow potatoes, sugar beet and peas widely. Lower pesticide use was the result, and furthermore resistance risks were reduced if other crops were involved in the rotation. By cultivating winter and summer crops alternately, she added, change in the active ingredients used for crop protection could be realized, and this could prove important in the future if certain active ingredients could be eliminated. Another benefit highlighted by Ms Riske was that having more crops in the rotation levelled out the work peaks on the farm and made harvest time more manageable. For the same reason, she noted that the farm's income was more balanced, which helped the business. With its current crops and crop rotations, she concluded, the risks faced by the Agrar GbR Groß Kiesow farm could be minimized.

The DLG-Feldtage takes place from 12 to 14 June 2018 at the DLG's International Crop Production Center at Bernburg (Sachsen-Anhalt). The event is co-organized by the State of Saxony-Anhalt's Ministry of Environment, Agriculture and Energy, and Allianz, together with Münchener und Magdeburger Agrarversicherung AG (Munich and Magdeburg Agricultural Insurance). Trade partners are: Fachagentur Nachwachsende Rohstoffe e.V. (Agency for Renewable Resources), Union zur Förderung der Öl- und Proteinpflanzen (Union for the Promotion of Oil and Protein Plants) and Nordzucker AG.

More information on the DLG-Feldtage 2018 is available online at: www.dlg-feldtage.de