2024-01-28 07:31:10
Producing humus: “no-till” is not always synonymous with climate protection
Karl Bockholt, AGRARHEUTE*
© agrarfoto
Spade sample for increasing humus levels: to protect the climate, it is not enough to conserve existing humus stocks as carbon reservoirs. An analysis of 100 recent publications on carbon (C) storage in soils shows that the vast majority use the terms incorrectly or ambiguously. To be able to assess humus formation, the differences between carbon sinks, negative emissions, climate protection and humus formation must be clear.
In the climate protection debate, technical terms are not always used correctly. This is not a question of playing with words. Imprecise expressions can lead to exaggerated expectations, for example regarding pfluglose Bodenbearbeitung. AGRARHEUTE provides clarification.
Carbon storage, carbon sink – are they the same thing? Does the fixation of carbon in the soil through the formation of humus automatically lead to better climate protection? In the debate on climate protection, many things are confused. Even scientific publications do not always use technical terms correctly. This is what a recent study shows, in which 100 international publications were analyzed.
What do we mean by a carbon (C) sink?
The soil system study focused on the following terms:
What do we mean by that? Carbon that escapes from soils as carbon dioxide (CO2), a greenhouse gas, and is therefore emitted into the atmosphere, can be captured once more and fixed in the soil as humus , without harming the climate. If, in a balance, the quantity of C from the atmosphere fixed in the soil is greater than that emitted, we speak of negative emissions or C sequestration. Additional carbon must therefore be stored in the soil in the form of humus (carbon sink). For this, it is not enough to conserve existing humus stocks as C reservoirs.
Why do many soils lose carbon (C)?
Terms must be used correctly. “Many fields in Europe are currently losing humus and therefore soil carbon due to climate change or unsustainable exploitation,” explains Professor Axel Don of the Thünen Institute for Agricultural Climate Protection, at Braunschweig. Numerous possibilities for reconstituting humus will therefore initially only reduce or stop the loss of C on surfaces. This does not lead to a sequestration of C, but “only” to a reduction in the loss of C. There will therefore be no negative emissions at this location, because greenhouse gas emissions will always be higher to the sequestration of CO2 by the reconstitution of humus.
How is reduced tillage really useful for climate protection?
It is nevertheless good for the climate if emissions decrease compared to before. But only if it doesn’t lead to additional emissions elsewhere. This is a condition for being able to assess whether the constitution of humus really contributes to climate protection. Reduced tillage can at the same time increase nitrous oxide emissions from the soil. Since nitrous oxide is almost 300 times more harmful to the climate than CO2, small additional quantities can destroy the climate protection effect of humus formation. Or even lead to an overall increase in greenhouse gases.
How are all greenhouse gas emissions taken into account?
If we want to evaluate the climatic effect of humus formation, we must therefore take into account all greenhouse gas emissions. Otherwise, we risk drawing completely erroneous conclusions. If all effects are added up and there are still more sequestered greenhouse gases than emissions, then the term negative emissions is correct.
What does the analysis of publications on humus formation show?
Analysis of 100 recent publications on C sequestration in soils shows that the vast majority use the terms incorrectly or ambiguously.
A new publication by Thünen clarifies the definitions and differences between:
sequestration of C:
negative emissions;
climate protection and
formation d’humus.
In doing so, researchers address the pitfalls associated with these terms. This should improve communication between science, politics, business and society, in order to better assess the contribution of humus formation to climate protection. You will find the full study here.
With material from the Thünen Institute.
_________________
* Karl Bockholt is cross-media editor at AGRARHEUTE, responsible for field crops and meadows. He has worked for more than 30 years at the Deutscher Landwirtschaftsverlag (dlv), following having worked for Feld & Wald (Girardet) and agrar-praxis (Konradin). A qualified farmer and engineer, he runs his farm in Münsterland as a sideline. He is a horseman, hunter and nature lover.
Source: Building humus: Plowless farming does not always equal climate protection | agrarheute.com
My note: The study, “Carbon sequestration in soils and climate change mitigation—Definitions and pitfalls” is international and includes French researchers. The authors are: Axel Don, Felix Seidel, Jens Leifeld, Thomas Kätterer, Manuel Martin, Sylvain Pellerin, David Emde, Daria Seitz, Claire Chenu.
1706525332
#Producing #humus #notill #synonymous #climate #protection
