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13.03.2019 – 17:23

Technische Universität München

Meta-analysis of yield stability compares organic and conventional agriculture

TECHNICAL UNIVERSITY OF MUNICH

Corporate Communications Center

phone: +49 89 289 10510 - e-mail: presse@tum.de - web: www.tum.de

This text on the web: https://www.tum.de/nc/en/about-tum/news/press-releases/detail/article/35285/

High resulution images: https://mediatum.ub.tum.de/1481587

NEWS RELEASE

The distinction between absolute and relative stability

Meta-analysis of yield stability compares organic and conventional agriculture

In agriculture, it is not only yield that counts, But also the stability of yields over several years. A meta-analysis by a team from the Technical University of Munich (TUM) and Agroscope in Zurich has investigated how organic and conventional agriculture differ in this regard.

Improving global food production and security is one of the biggest challenges of our time. The goal of organic agriculture is to minimize the negative effects on humans and nature by avoiding mineral fertilizers and synthetically produced pesticides.

In addition, stable agricultural production is important - especially in view of the expected greater fluctuations due to climate change. But so far there is little knowledge about how organic and conventional agriculture differ in terms of annual yield fluctuations.

Samuel Knapp from the Chair of Plant Nutrition at the Technical University of Munich and Marcel van der Heijden from the Swiss Center for Agricultural Research, Agroscope, thus investigated annual yield variations in a meta-analysis of previously published studies.

In total, they used165 direct comparisons from 39 published studies. As expected, the analysis confirmed that organic farming produces lower yields than conventional farming - on average 16 percent lower across all crops.

Similar yield fluctuations, but different yield levels

However, the variations in yields were very similar over the years in both cultivation systems. "While this may sound reassuring, it does have a catch," says Samuel Knapp. "Because the absolute yield variations are similar, the fluctuations in the lower yields of organic farming have a greater impact. The so-called relative yield stability is therefore lower in organic farming."

The differences in stability between the two cultivation systems can be attributed, among other things, to higher fertilization with nitrogen and phosphorus in conventional cultivation. Organic farms can improve their yield stability with green manure and time-optimized fertilization.

The effect of reduced tillage

In their study, the researchers also investigated the effect of reduced tillage. This often has a positive effect on soil structure and soil organisms, but is also known to result in slightly lower yields.

The two scientists compared the yield stability in 367 paired, long-term comparisons of reduced and conventional tillage. The result: The difference in yield, although measurable, amounted to merely two percent. The researchers found no significant differences regarding yield stability.

More information:

The project was funded by the Swiss Competence Center for Agricultural Research, Agroscope and the Swiss National Science Foundation.

Publication:

S. Knapp, M.G.A. van der Heijden

A global meta-analysis of yield stability in organic and conservation agriculture.

Nature Communications 9, 3632, 2018 - DOI: 10.1038/s41467-018-05956-1

https://www.nature.com/articles/s41467-018-05956-1

High resolution images:

https://mediatum.ub.tum.de/1481587

Contact:

Samuel Knapp

Technical University of Munich

Chair of Plant Nutrition

Tel.: +49 8161 71 3390 - E-mail: pnut@wzw.tum.de

Web: http://www.pe.wzw.tum.de

The Technical University of Munich (TUM) is one of Europe's leading research
universities, with around 550 professors, 42,000 students, and 10,000 academic
and non-academic staff. Its focus areas are the engineering sciences, natural
sciences, life sciences and medicine, combined with economic and social
sciences. TUM acts as an entrepreneurial university that promotes talents and
creates value for society. In that it profits from having strong partners in
science and industry. It is represented worldwide with the TUM Asia campus in
Singapore as well as offices in Beijing, Brussels, Cairo, Mumbai, San Francisco,
and São Paulo. Nobel Prize winners and inventors such as Rudolf Diesel, Carl von
Linde, and Rudolf Mößbauer have done research at TUM. In 2006 and 2012 it won
recognition as a German "Excellence University." In international rankings, TUM
regularly places among the best universities in Germany. www.tum.de
More stories: Technische Universität München
More stories: Technische Universität München