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Can humus save our climate?

Business Model Climate Farming ...
is the headline of the trade press. Of course, we don't begrudge any farmer expanded sources of financial income. And maybe it also helps to polish up the bad image of agriculture, which is mostly created by the media. On closer inspection, however, one realises that an expectation is being raised here that cannot be anchored in reality. It is to be expected that resourceful businessmen want to establish a flourishing business as free riders with the certificate trade.

My recommendation: Hands off!

Prof. Körschens, together with the Förderverband Humus e.V. (Humus Promotion Association), takes a stand on this from an arable farming perspective. This group of scientists has devoted almost their entire life's work to the establishment, investigation and evaluation of long-term experiments on humus. See also www.agrarfakten.de
Peer Leithold


Can humus save our climate?

Prof. Dr. habil. Dr. h. c. Martin Körschens,
Förderverband Humus e. V.
Goethestadt Bad Lauchstädt
e-mail: m.koerschens@t-online.de

No one doubts that the climate is changing, and it has changed several times over the past millennia (cf. DAHM et al, 2015, et al.).  For example, less than a thousand years ago Greenland was still a "green country".

There are different opinions about the causes of climate change. The IPCC assumes that a man-made increase in the atmospheric
CO2 concentration in the atmosphere is the cause. There is obviously insufficient evidence for this. Irrespective of these different opinions, scientists, politicians and business people see the soil, i.e. humus, as a carbon sink and thus the possibility of simply storing the excess CO2 from the atmosphere in the soil.

Numerous speculations and misconceptions surround this problem. For example, the EU (in a Communication from the Commission of the European Communities to the Council, the European Parliament, the Economic and Social Committee and the Committee of the Regions, 2003) claimed that "soils with an organic matter content of less than 3.6% are in the preliminary stages of desertification." According to this view, Europe is already a desert. Yet in this "desert", yields have multiplied over the past hundred years. Thanks to the successful work of farmers and agricultural research, today more than 10 t/ha of winter wheat are harvested annually in some places, and soil fertility has increased significantly in this "desert".

Bioenergy - limits and possibilities

In its study "Bioenergy - Limits and Possibilities", the LEOPOLDINA (2012) announced annual carbon losses of arable soils in the EU of 3 %, a statement that is completely untenable from a purely mathematical point of view and could be disproved beyond doubt by the results of numerous continuous field trials and many other studies. The hypotheses of humus as a "climate saviour" are, however, politically and economically very welcome, as one can name the culprits, make political capital out of it and engage in a brisk trade in CO2 certificates. According to official statements, Deutsche Bank has earned billions from emissions trading and "is alleged to have been involved in the fraudulent trading of emissions certificates."

In Austria, one trades the tonne of CO2 at €30 and can earn a lot of money with it.

First of all, the following facts have to be assumed: An increase in humus content can only be achieved by an additional amount of C removed from the atmosphere (photosynthesis) via the plant. All other measures mentioned, such as avoidance of fallow periods, intercropping and inter-row cultivation as well as grass strips, agroforestry, optimal pasture management and extension of the grazing period, restoration of land under poor condition, etc., have only marginal significance, if any, for this objective and are more or less part of good professional practice.


Increase in humus content is limited

The possibilities for increasing the humus content are very limited. The differentiation of humus into nutritive humus and permanent humus has been known since time immemorial, but today it is ignored and almost exclusively the total humus content is evaluated, which inevitably leads to irritations and misinterpretations. Only the nutrient humus can be influenced in measurable periods of time. The content of permanent humus-C (arable land) is predominantly between 0.3 and 1.5 % Corg. The nutrient humus-C that can be influenced by management measures in the tillage horizon is on average 0.3 % and often accounts for less than 0.2 % Corg, i.e. about 10 t/ha (in 32 of 68 Daufeld trials, mainly on sandy soils) and rarely exceeds 0.5 % Corg. (only in 11 of a total of 68 permanent field trials).

Excessive humus contents reduce the utilisation of soil N and increase atmospheric pollution with CO2, N2O and CH4.

90 % of the organic primary substance (OPS) added to the soil, based on the initial substance of plant biomass, is re-mineralised and returned to the atmosphere (HAIDER, 1997, KÖRSCHENS, 2017 et al.), i.e. for an increase of the Corg content in the soil by only 0.1 %, an application rate of >100 t/ha plant dry matter is necessary in the long term (cf. www.agrarfakten.de).

The French government's initiative "4 0/00 annual growth of the C stock" has no chance, because with a C accumulation of only 10 % annually, utopian amounts of additional plant dry matter would have to be applied to the soil. If we assume the figure of 1.2 billion t C given in the initiative, this would be at least about 500 kg C/ha annually x 10 = 5 t OPS-C = 12.5 t/ha plant dry matter (40 % C in the dry matter), i.e. a complete harvest.

This largely eliminates the discussion about "carbon sequestration", possibilities for which are limited to a few exceptions. Moreover, an increase is neither beneficial for yield formation nor for the environment.

In the media, simple ways of saving the climate are presented, mostly by laymen. For example, SCHEUB/SCHWARZER (2018) formulate in the book "The humus revolution": "A global humus increase of just one percentage point could take 500 gigatonnes of CO2 out of the atmosphere. This would bring the current CO2 content of the air to a largely harmless level".

The amount stated here is roughly a hundred times what the French government's initiative proposes. Such ideas about saving the climate, as also advocated by RAGGAM (2008) in Austria and disseminated on television, belong to the realm of fantasy, lack any expertise and only serve to attract attention. That everything is done to maintain and increase soil fertility and thus to increase yields is self-evident and has always been done by farmers. But one should not be under the illusion that a significant increase in the carbon content and thus a reduction in the CO2 concentration of the atmosphere can be achieved and thus that the future of our planet is in the hands of the farmers. Being a farmer is a demanding and multifaceted profession. But no farmer would think of advising a doctor how to perform a heart valve operation. No doctor would think of suggesting to an engineer how to build a spaceship. Only some politicians or unskilled workers are so presumptuous as to want to tell a farmer how to cultivate his land.

5 comment(s) for "Can humus save our climate?"

Markus Müller wrote on 19.11.2020, 09:37 - Autoren-Riege vielleicht doch zu alt? Ich kann mich meinen Vorrednern nur anschließen. Es gibt mittlerweile genügend, vor allem praktische, Beispiele, dass ein Humusaufbau nicht nur möglich, sondern auch sinnvoll ist damit auch langfristig betriebswirtschaftliche Vorteile für den Landwirt bringt. Und wenn ich mir das Gros der Autoren von der rezitierten Seite so anschaue: http://www.agrarfakten.de/autoren/ ... sind die meisten bereits weit über 60 Jahre alt, viel frischer Wind ist da nicht gerade dabei und es ist kein Geheimnis, sich mit steigendem Alter neuen Dingen eher seltener zu widmen und stärker auf der eigenen Meinung zu beharren. Meist ist es doch immer ein Mittelweg, der am Stärksten an der Wahrheit liegt. Und wie leider so oft werden wissenschaftlich fundierte Gegenbeispiele außer Acht gelassen, wie z.B. die Direktsaat nun wirklich eindeutig nachweisbar nicht nur Bodenleben und Humusgehalt verbessert, sondern auch auf guten Standorten vom Ertragsniveau her mithalten kann: https://www.vol.be.ch/vol/de/index/landwirtschaft/landwirtschaft/bodenschutz/bodenzustand/dauerbeobachtungsflaecheoberacker.html?fbclid=IwAR0C82mIokJeiFUChTvZ7-wtkN7QBxBsf0Re5ySpT4sF7--sVuykSxszT4I

Dr. Albrecht Kloss wrote on 13.11.2020, 11:19 Interessante Frage, was sagt Schöneberger ? Antwort kommt auf die Gage an, wie hoch sie ist. Die Welt wird immer bekloppter. Humus solls richten.

Stefan Schwarzer wrote on 09.11.2020, 07:43 - Sich für das Neue öffnen Nun, während sich eine zunehmende Anzahl von Wissenschaftlern und Praktikern neuen Methoden öffnen, die in Praxis und zunehmend auch in der Forschung zeigen, wie ein wirklicher Humusaufbau geht und dies teilweise recht gut dokumentieren, meint Herr Körschens es besser zu wissen. Die Angaben zur CO2-Sequestrierung im Boden z.B. im zitierten Buch sind alle Peer-reviewed Publikationen von Wissenschaftlern - bitte mit denen mal sich auseinandersetzen. Und mit den Praktikern sprechen, die ganz praktisch tatsächlich andere Erfahrungen machen. Können die vielleicht zaubern? Oder entgegen der Naturgesetze arbeiten? Nein, sie haben verstanden wie die Beziehungen in der Natur funktionieren - dass z.B. die Pflanze große Mengen an Kohlenstoff als Wurzelexudat in den Boden pumpt um das Bodenleben zu füttern. Und dass diese Ausscheidungen ein 2-10 Mal höheren Faktor bei der Humusbildung spielen als Streu. Sehr spannend!
Und ja, Humuszertifikate - kein einfaches Thema. Da bin ich auch zurück haltend, was die Sinnhaftigkeit und Dauerhaftigkeit angeht.

Michael Reber wrote on 05.11.2020, 18:48 - Veraltetes Wissen Schade, dass hier auf dieser Plattform mit vollkommen veraltetem Wissen gearbeitet wird. Wie z.B. ganz aktuell Gernot Bodner von der BOKU Wien bei Vorträgen bei der DSV ganz klar gemacht hat, entstehen stabile Humusverbindungen vor allem durch Mikrobiologie. Die alten Professoren glauben immer noch, dass es nur mit toter organischer Substanz gehen kann und dann kommen solche Artikel dabei raus. Es wäre schön gewesen, wenn Sie dazu besser recherchiert hätten.
Trotzdem bin auch ich der Meinung, dass der Zertifikatehandel nur einem nützt: dem Händler. Der Anspruch des Bauern sollte sein, seine Böden einfach klimafit zu machen.
Gruß Michael Reber

Christian Dreyer wrote on 05.11.2020, 11:46 - Humus Was der große Gelehrte Herr Prof. Dr. Schönberger wohl zu dem Artikel von Dr. Körschens sagen wird .....

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