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125th anniversary celebrated at Askov Experimental Station

Aarhus University’s long-term field experiments on manure and mineral fertilisers at Askov Experimental Station have provided soil, plants and data for a wide range of studies over the years. Some of the results were presented at the celebration of the 125th anniversary of the experiments.

[Translate to English:] Professor David S. Powlson fra Rothamsted Research overrakte et tillykke-certifikat til rektor Brian Bech Nielsen, Aarhus Universitet i anledning af 125 års-jubilæet. Foto: Janne Hansen
[Translate to English:] Professor David S. Powlson fra Rothamsted Research overrakte et tillykke-certifikat til rektor Brian Bech Nielsen, Aarhus Universitet i anledning af 125 års-jubilæet. Foto: Janne Hansen

People came from far and near to celebrate that the Department of Agroecology at Aarhus University’s long-term experiments at Askov Experimental Station held their 125th anniversary on 11 June 2019. Researchers from Oxford, Rothamsted, Newcastle, Jülich – and Denmark presented research based on samples from the long-term experiments. 

The visitors were researchers, advisors, companies, and authorities, as well as the mayor of Vejen Municipality and the rector of Aarhus University – all told about 70 participants. And despite pouring rain, thunder and lightning, it was a festive and interesting day that demonstrated the value of the long-term experiments. Even walking around in a wet version of the research fields was not a hindrance. 

The visitors were welcomed in talks given by Section Manager Jørgen Eriksen, Department of Agroecology, Aarhus University, and the university’s rector, Brian Bech Nielsen, followed by Professor Bent T. Christensen, Department of Agroecology. Professor David S. Powlson from Rothamsted Research had the grand overview when he spoke of the value of long-term field experiments in a global perspective, after which he presented Rector Brian Bech Nielsen and Professor Bent T. Christensen with a special congratulatory certificate from Rothamsted’s director.

The following presentations went down a very broad avenue that demonstrated how the Askov long-term experiments have contributed to research in prehistoric agriculture, antibiotic resistance and accumulation of uranium in the soil. The presentations showed how the experiments have acted as a research platform within a wide variety of research areas, and that there are no limits to new ideas. 

Prehistoric farming, genetic secrets and uranium   

Professor Amy Bogaard from the University of Oxford explained how archaeologists can reconstruct prehistoric growing conditions and practices with the aid of isotope analyses of archaeological finds of grain and of grains from prehistoric cereals grown in the long-term experiments at Askov and Rothamsted. This can shed light on when manuring was invented! Bent T. Christensen called this branch of science ”agroarchaeology”, a concept which has stuck in archaeology.  

The soil’s microbiome carries a genetic fingerprint that can also tell a story. Senior Researcher Jan Dolfing from Newcastle University has delved into this area. Using soil samples from historic soil archives associated with long-term experiments, he found that applications of animal manure increase the presence of antibiotic resistance genes in the soil. Most importantly, he found that when a certain type of antibiotic is phased out, the presence of corresponding resistance genes decreases over a period of about 10 years.

Read the article ”Antibiotics use affects the abundance of resistant bacteria in soil” here. 

Professor Roland Bol and his PhD student Yajie Sun explained that long-term manure experiments can be used to follow long-term accumulation of uranium in soils subjected to annual applications of phosphorous fertiliser. Plants can absorb uranium or it can be transported down into the soil profile, but in what amounts remains an open question. 

The long-term experiments at Askov Experimental Station show a slight rise in uranium content irrespective of nutrient treatments. This can be ascribed to atmospheric deposition. In Askov, application of phosphorous fertiliser has not led to increased accumulation of uranium. Historically, the fertiliser used in Scandinavia comes from Finland, where the raw phosphate has a low uranium content. Long-term field trials in other parts of the world show that use of raw phosphate from other locations can result in accumulation of uranium. 

Long-term effects of nitrogen fertilisation

Johannes Lund Jensen, PhD student in the Department of Agroecology, spoke about the availability and effects of the residual nitrogen, retained in the soil after many years of animal manure and mineral fertiliser applications. These studies were also based on the experiments in Askov. He emphasised that it is essential to account for the effects of nitrogen retention in the soil when establishing regulation application rates of nitrogen fertiliser.   

The intention was that the visitors could take a tour in the field after the talks but fortunately, there was a plan B. The Danish summer weather was at its most capricious with heavy rain, thunder and lightning, so instead the current studies at Askov were presented by Department of Agroecology researchers with the aid of indoor posters. However, when the rain let up, everyone went out into the field with Askov manager Henning C. Thomsen in the lead. Researchers are indomitable when it comes to a unique opportunity to experience 125 years of fertilisation! 

The DCA report “The Askov long-term experiments: 1894-2019” has been published in connection with the 125 year anniversary. You can download the report here.

For more information please contact

Professor Bent T. Christensen, Department of Agroecology, email: bent.t.christensen@agro.au.dk, telephone: +45 8715 7764