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Unknown User (fabian.rackelmann)
Hi Marc, thanks for sharing! Does the twin-regions project between Sinendé and Alfter already exist, or is it just an example how it could look alike? If there are already twin-regions - how many of them are there by now?
It sounds reasonable to me that phosphorus as a soil ammendment to the old eroded african soils would boost the creation of organic matter through plant growth and thus SOC (to acertain degree). However, the slide (without a presentation) gives the impression that the sole p-ammendment would lead in any case to an enrichment of SOC (which certainly is not the case). Consider to highlight here the neccesity for a concomitant and adequate sustainable land management. Furthermore, I wonder how you have estimated the saturation time of the carbon stocks of the respective land forms? To me, they appear to be very short.
Good comment. I am glad you raise the more technical questions about SOC sequestration potential, and in particular the issue of saturation, and I hope others will join the discussion and contribute to a better understanding of the relevant factors and assessment of theoretical and realistic potential. You are correct. The numbers in the presentation are shaky, no question. However, it is important to point out that, unlike Zomer et al. in, we are referring to carbon capture potential of all land use systems. As you can see on slide 8, we also include other land uses, not just cropland. Zomer et al. only look at cropland. In fact, the numbers in the table clearly show that our preliminary conclusion is that the potential for SOC sequestration on cropland in SSA is very limited.
My general sense is that many of our conclusions are model-based and that it is important to do some field experiments to evaluate the theoretical and realistic potential and to better understand the dynamics in a more holistic approach. Secondary effects also need to be considered. I also believe that we should go far beyond SOC / SC and look at the carbon budget of regions by considering all fixed forms of organic carbon including living above and below ground biomass. I would also like to emphasize here that soils are inherently not a good environment for carbon storage; on the contrary, they are probably one of the worst places to be, especially with increasing temperatures and precipitation. For example, it might make more sense to use plants only to capture carbon, but store it in buildings. What would happen if, by law, 20% of all building materials had to be wood while maintaining or increasing the area covered by forests ?
When we recently discussed the Twin Regions with Le Foll, he mentioned the concept of bio-economy / the economics of photosynthesis. Soil, soil health and consequently soil nutrition are certainly key factors of such an economy. SOC is important and it will likely increase with the improved carbon balance of a region. But I think we are making a fundamental mistake if we make increasing SOC our primary goal. Changing course and going after the overall carbon balance of regions would also free us from having to demonstrate SOC change.
Finally, I want to emphasize that the primary purpose of the twin regions concept is to propose a mechanism for getting things right that is fair and makes the best use of our resource base. It goes beyond the SOC.
8.5.19, themed by Refined
4 Comments
Unknown User (fabian.rackelmann)
Hi Marc, thanks for sharing! Does the twin-regions project between Sinendé and Alfter already exist, or is it just an example how it could look alike? If there are already twin-regions - how many of them are there by now?
Marc Bernard
Hi Unknown User (fabian.rackelmann), no, it just an example to show the idea.
Unknown User (fabian.rackelmann)
I have some questions/comments regarding the "potential" slides:
I assume that soil organic carbon sequestration is meant.
Where did you derive the info from that SSA has the greatest potential for SOC sequestration? Zomer et al. draw a bit more modest picture: https://www.nature.com/articles/s41598-017-15794-8
It sounds reasonable to me that phosphorus as a soil ammendment to the old eroded african soils would boost the creation of organic matter through plant growth and thus SOC (to acertain degree). However, the slide (without a presentation) gives the impression that the sole p-ammendment would lead in any case to an enrichment of SOC (which certainly is not the case). Consider to highlight here the neccesity for a concomitant and adequate sustainable land management. Furthermore, I wonder how you have estimated the saturation time of the carbon stocks of the respective land forms? To me, they appear to be very short.
Best regards,
Fabian
Marc Bernard
Good comment. I am glad you raise the more technical questions about SOC sequestration potential, and in particular the issue of saturation, and I hope others will join the discussion and contribute to a better understanding of the relevant factors and assessment of theoretical and realistic potential. You are correct. The numbers in the presentation are shaky, no question. However, it is important to point out that, unlike Zomer et al. in, we are referring to carbon capture potential of all land use systems. As you can see on slide 8, we also include other land uses, not just cropland. Zomer et al. only look at cropland. In fact, the numbers in the table clearly show that our preliminary conclusion is that the potential for SOC sequestration on cropland in SSA is very limited.
My general sense is that many of our conclusions are model-based and that it is important to do some field experiments to evaluate the theoretical and realistic potential and to better understand the dynamics in a more holistic approach. Secondary effects also need to be considered. I also believe that we should go far beyond SOC / SC and look at the carbon budget of regions by considering all fixed forms of organic carbon including living above and below ground biomass. I would also like to emphasize here that soils are inherently not a good environment for carbon storage; on the contrary, they are probably one of the worst places to be, especially with increasing temperatures and precipitation. For example, it might make more sense to use plants only to capture carbon, but store it in buildings. What would happen if, by law, 20% of all building materials had to be wood while maintaining or increasing the area covered by forests ?
When we recently discussed the Twin Regions with Le Foll, he mentioned the concept of bio-economy / the economics of photosynthesis. Soil, soil health and consequently soil nutrition are certainly key factors of such an economy. SOC is important and it will likely increase with the improved carbon balance of a region. But I think we are making a fundamental mistake if we make increasing SOC our primary goal. Changing course and going after the overall carbon balance of regions would also free us from having to demonstrate SOC change.
Finally, I want to emphasize that the primary purpose of the twin regions concept is to propose a mechanism for getting things right that is fair and makes the best use of our resource base. It goes beyond the SOC.
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