Bioeconomy Showcase: Circular Economy Instead of Phosphorus Crisis

April 06, 2020

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(University of Hohenheim (Google Translation)) German-Chinese Research Training Groups at the University of Hohenheim and the China Agricultural University in Beijing are looking for solutions for sustainable phosphorus use using the example of maize cultivation systems

If it is not possible to use the resource phosphorus more sustainably, mankind is heading for a serious crisis: phosphorus is irreplaceable as a nutrient for plants, animals and people. If it gets back into the soil via excretions or dead organic material, the cycle closes. At the moment, however, agricultural production worldwide cannot do without mineral fertilizers with considerable amounts of additional phosphate, which must be mined in natural deposits. However, these deposits counteract their exhaustion and are also extremely unevenly distributed worldwide. On the other hand, environmental problems often occur in areas with high livestock density, because too much phosphate is spread in the fields via manure. A German-Chinese Research Training Group is currently researching approaches to the complex global problem using the example of maize cultivation systems. The goal: a sustainable circular economy in the sense of the bioeconomy. The joint doctoral training at the University of Hohenheim in Stuttgart and the China Agricultural University (CAU) in Beijing has been funded by the DFG since October 2018.

If the current economy does not change, it is estimated that natural phosphorus deposits will be exhausted in about 250-300 years. What sounds like a comparatively long period of time is already being felt by farmers in the rising prices for fertilizers.

And inflation could escalate further dramatically in the coming decades. Because deposits of poor quality, which can be contaminated by heavy metals such as cadmium and uranium, are increasingly being mined. The raw phosphate obtained there must first be processed cost-intensively.

Another problem is the uneven distribution of the resource. Almost three quarters of the known deposits are located in only one country in the world: Morocco. Unstable political conditions there could have a serious impact on the entire world market in the future.

Phosphorus crisis: German-Chinese cooperation looks at global problem

"If we don't start looking for alternative solutions today and are on the way to a circular economy in the sense of the bioeconomy, we are heading for a serious crisis", emphasizes Prof. Dr. Torsten Müller from the Department of Fertilization and Soil Management at the University of Hohenheim and spokesman for the German-Chinese Research Training Group on the German side.

A total of 35 doctoral students from the University of Hohenheim and the China Agricultural University in Beijing are researching precisely such solutions as part of the joint training program "Adaptation of maize-based food-feed-energy systems to limited phosphate resources (AMAIZE-P)". In mixed German-Chinese tandem teams, the young scientists use the example of maize cultivation systems to examine different starting points in order to use the scarce resource phosphorus as effectively as possible.

In fact, China, as the most populous country in the world, will experience the shortage of phosphorus particularly strongly in the future: the People's Republic is still relying on mining areas in its own country. But these are likely to be exhausted in about 35 years with constant consumption. If the current phosphorus demand of Chinese agriculture has to be covered 100% on the world market in the future, this would also have consequences for the rest of the world: prices make another big leap upwards.

"The paradox of the current situation is that there are regions in both Germany and China in which phosphate is used almost wastefully: Wherever there is a lot of livestock farming and biogas production in Germany, environmental problems arise because of manure and digestate residues too much phosphate ends up in the fields. Similarly, in China, the phosphate from organic sources is hardly taken into account when determining fertilizer requirements, while the use of mineral fertilizers is excessive. Soils cannot fully absorb the nutrient and it gets into streams, rivers and lakes in considerable quantities. This leads to eutrophication, which among other things can result in a pronounced algal bloom. In addition, phosphate is lost via the waste water and waste streams from the agricultural cycles, " explains Prof. Dr. Miller.

Take maize cultivation, for example: interdisciplinary approaches to a variety of scenarios.

Although the challenges in Germany and China look similar at first glance, there are also major differences. Because the agricultural sector in both countries is structured differently: While larger companies dominate in Germany, Chinese agriculture is still largely characterized by small farmers. The climatic conditions of the two countries are also very different.

“It is precisely these differences that are so valuable for research cooperation. With parallel field trials and economic analyzes in Germany and China, we can cover a large part of the scenarios that arise worldwide. The conditions in Germany and China complement each other particularly when it comes to our subject of study, the maize crops: together we can cover almost all production systems that play a role worldwide, ”says Dr. Marco Roelcke, coordinator of the German-Chinese Research Training Group on the German side.

The crop maize, which is one of the most important staple foods worldwide, is particularly well suited to the broad research approach due to its wide range of possible uses: Because corn serves as food for humans, as feed - in the form of grains or as silage - for oil production and as a biomass supplier for energy production or the production of basic chemicals through new conversion processes in the sense of the bioeconomy.

Compensate for surplus and shortage

In twelve interdisciplinary working groups, German and Chinese doctoral students pursue a wide range of solutions.

"An important focus is on sustainable fertilization strategies and the question of how excess phosphate from regions with high livestock density can be transferred in a resource-saving manner to arable regions with a phosphate deficiency," explains Prof. Dr. Miller. “In retrospect, it was a wrong political decision to promote structural change with spatial differentiation between these two economic forms. However, in the foreseeable future there will be no way back to the traditional mixed companies. So we have to look for technological solutions to deal with the existing situation. ”

Basically, plants can only utilize phosphorus efficiently if at the same time they also have sufficient amounts of all other nutrients, such as nitrogen. One problem with fertilizing with liquid manure and fermentation residues is that nitrogen and phosphorus are not optimally combined. The plants cannot absorb the excess phosphate and are therefore lost unused.

To solve this problem, research groups at the Research Training Group are researching practical ways of further processing manure and digestate in order to separate the nitrogen and phosphorus flows again and to make optimal use of these two nutrients. In a win-win situation, energy and basic chemicals should also be generated.

New corn varieties, optimized crop rotations, nutrient recovery

In addition, the German-Chinese working groups are also working on completely different levers: For example, the breeding of new corn varieties that absorb the nutrients better via their roots, or the optimization of crop rotations because of the alternation of corn and Legumes the phosphate can be made more available in the soil. Other sub-projects deal with the use of phosphate in the digestive tract of humans and farm animals.

“Human excretions are also a source of phosphate that can be fed back into the cycle. Due to the current legal situation in Germany, sewage sludge can hardly be applied directly to fields. We think: sewage sludge is better than its reputation - and we are therefore looking for ways to recover the phosphate it contains in large sewage treatment plants, ”says Prof. Dr. Miller.

Think Tank: Interdisciplinary exchange in the block seminar

“A block seminar, which takes place alternately in Germany and in China, ensures the interdisciplinary exchange of all teams twice a year: a think tank that is enriched by external experts from all over the world. The doctoral training is accompanied by intercultural training, career workshops and numerous other formats, ”reports Dr. Roelcke.

The fourth block seminar took place from 9th to 16th March 2020 at the University of Hohenheim and at the Unteren Lindenhof in Eningen unter Achalm and was under the umbrella theme "P-nutrition and recovery".

"As only the Chinese doctoral students who had already been in Germany could be present in person due to the Corona crisis, their colleagues who stayed in China provided PowerPoint presentations or video files with sound recordings, which were then shown in the seminar. Conversely, all lectures and discussions of the block seminar were also recorded. We will certainly continue to benefit from the tried and tested forms of digital collaboration in the future, ”said Dr. Roelcke convinced.

The Research Training Group is also closely networked with the CHIKOH program - Chinakompetenz Hohenheim: Since October 2017, the program has strengthened the China expertise of scientists and students with a wide range of offers. The University of Hohenheim wants to actively contribute to the mutual transfer between business and science with excursions and workshops. An important item on the program is the “Hohenheim China Dialog” as an exchange platform for representatives from science, business and society from the region.

BACKGROUND: China Agricultural University (CAU), Beijing

The China Agricultural University (CAU) in Beijing is the leading university in Asia in the field of agricultural sciences and is always among the first places in global rankings. CAU scientists conduct research and teach in the fields of agriculture, life sciences, resources, the environment, electronic data processing, computer science, agricultural engineering, management and social sciences. The University of Hohenheim and the CAU maintain one of the oldest existing German-Chinese university partnerships (since 1979). In November 2019, the 40th anniversary of this unique friendship was celebrated in Beijing.

BACKGROUND: Science Year 2020 Bioeconomy

In 2020, the science year organized by the Federal Ministry of Education and Research (BMBF) will focus on the bioeconomy - and thus on a sustainable, bio-based economy. The aim is to produce and use natural substances and resources in a sustainable and innovative way, thereby replacing fossil and mineral raw materials, making products more environmentally friendly and conserving biological resources. This is necessary more than ever in times of climate change, a growing world population and a drastic decline in species. The Bioeconomy Science Year puts the spotlight on the topic.

Bioeconomy is the main theme of the University of Hohenheim in research and teaching. It connects the Faculties of Agricultural Sciences, Natural Sciences, Economics and Social Sciences. In the Bioeconomy Science Year, the University of Hohenheim informs experts and the public about the topic in numerous events. The monthly focus in March is: Conserving resources - circular economy and economic development. READ MORE

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