Red Baron Farms
Philosopher
I am starting this thread separate from the global warming thread because carbon sequestration and land use has its own merits only marginally related to the question of global warming. Please respect the topic so this thread doesn't get merged and we can discuss the emerging science without interference and interruptions. Contrary views are welcome, but please stay on topic.
Thanks for the links. I have seen all or parts of them before, usually as reference to part of another paper.
There are a couple things that I find troublesome, although the over-all gist is fair enough, as far as that goes.
A couple things that are bothering me that we could discuss.
"Removing land from annual cropping and converting to forest, grassland or perennial crops will remove C from atmospheric CO2 and genuinely contribute to climate change mitigation. However, indirect effects such as conversion of land elsewhere under native vegetation to agriculture could negate the benefit through increased CO2 emission. Re-vegetating degraded land, of limited value for food production, avoids this problem"
It seems to me they have completely ignored the possibility of converting to a food forest, or converting to grazed land, both of which can be quite productive in food, eliminating the undesirable indirect effect of needing to convert native vegetation to cropland elsewhere. And actually over all increasing total food production. In these cases "of limited value for food production" do not apply. This leads me to believe they are only considering conventional ag in this paper. I could have read that wrong though, because the wording in the text is somewhat less than precise. They might actually agree, but if so have created an internal conflict in their paper. In either case, converting cropland to grazed grassland does not necessarily reduce production at all. Particularly if the cropland was previously being used to grow livestock feeds which will then no longer be needed due to the animals eating grass. (or biofuels) The trend is exactly the opposite as stated actually. The more grassland converted to cropland, the more the pressure is to convert even more to cropland, because cropland is not nearly as productive as perennial grassland, all else equal.
Another problem I see with that one is " Limitations of C sequestration for climate change mitigation include the following constraints: (i) the quantity of C stored in soil is finite" or from the other study "Thus, the potential is finite in capacity and time. Nonetheless, soil C sequestration buys us time until the alternatives to fossil fuel take effect."
That's true, I mean sure the carbon on earth is finite. The % of that carbon in soils is finite. The coal oil and gas reserves are finite. It's all finite.
However, the implication is that you'll be able to sequester X in the soils, after that the soils will be "full" and we won't be able sequester more. Well, the forest biome does actually act that way in most cases. Exceptions being peat that gets ever deeper, and swamps that have a similar process, or areas of extreme cold where temperature halts the process of decay. But by far the majority of forests do approach a limit over time. So that's cool. No problem there.
Grasslands are different though. The way they sequester carbon is fundamentally different. They follow a completely different curve. It is not from leaf litter on top of the soil. It is a specific biological evolutionary adaptation grasses have for feeding the biome deep in the soil.
You can understand this better if you first understand Endomycorrhizal fungi, and Ectomycorrhizal fungi. As a general rule (with a fair number of exceptions) grasses use endo and trees and shrubs ecto. There is a specific mutualistic relationship between grasses and Endomycorrhizal fungi where the plant feeds the mycorrhizal fungi with sugars down deep where it would have no chances of surviving without help. The fungi repays this debt by supplying the plants with hard to get nutrients and with improved disease and pest resistance. ~ 20% of the products of photosynthesis are pumped directly into the soil biology as sugars feeding that biome, mostly Endomycorrhizal fungi. Then something else happens when a grass is grazed. It then has too much roots in ratio to growing top and to get back in balance it sheds a large quantity of root mass to achieve balance again within hours of being grazed. Endomycorrhizal fungi require a living root to survive. So that triggers the Endomycorrhizal fungi to spore up and the bulk of it dies. So that creates a large % of decaying material from both the plant roots and the Endomycorrhizal fungi which starts the food chain for a whole web of life deep in the soil where the greenhouse gasses have little chances of escaping. This ultimately results in new mollic soil creation and carbon sequestration for thousands of years. As the soil becomes more fertile, instead of tapering off towards a finite limit as in forests, it actually accelerates. This process continues into deep geological time unabated unless the biome is disturbed. (by something like a glacier, volcano, or human plow etc...)
Forests don't do this, they primarily use ectomycorrhizal fungi, and instead feed the soil biology from the top down with leaf litter. A large % of which after decay escapes to the atmosphere. Annual crops don't do this because although they do use Endomycorrhizal fungi their roots are by and large much too small and/or shallow, which allows the greenhouse gasses to escape at a rate close to or sometimes even exceeding the sequestration rate. That's why long term trends for these are either near net carbon neutral (forests), or an emissions source (annual crops).
There are a few more things I saw. But that gets the conversation started.
Soil Carbon Sequestration Impacts on Global Climate Change and Food Security
http://www.rowan.k12.ky.us/userfiles/959/Classes/10689/stegall kandra 11302011 327 pm soilcarbon.pdf
Soil carbon sequestration to mitigate climate change: a critical re-examination to identify the true and the false
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2389.2010.01342.x/abstract
The knowns, known unknowns and unknowns of sequestration of soil organic carbon
http://www.sciencedirect.com/science/article/pii/S0167880912003635
(any who are having a difficult time accessing the full version of this paper can contact me via PM)
Thanks for the links. I have seen all or parts of them before, usually as reference to part of another paper.
There are a couple things that I find troublesome, although the over-all gist is fair enough, as far as that goes.
A couple things that are bothering me that we could discuss.
"Removing land from annual cropping and converting to forest, grassland or perennial crops will remove C from atmospheric CO2 and genuinely contribute to climate change mitigation. However, indirect effects such as conversion of land elsewhere under native vegetation to agriculture could negate the benefit through increased CO2 emission. Re-vegetating degraded land, of limited value for food production, avoids this problem"
It seems to me they have completely ignored the possibility of converting to a food forest, or converting to grazed land, both of which can be quite productive in food, eliminating the undesirable indirect effect of needing to convert native vegetation to cropland elsewhere. And actually over all increasing total food production. In these cases "of limited value for food production" do not apply. This leads me to believe they are only considering conventional ag in this paper. I could have read that wrong though, because the wording in the text is somewhat less than precise. They might actually agree, but if so have created an internal conflict in their paper. In either case, converting cropland to grazed grassland does not necessarily reduce production at all. Particularly if the cropland was previously being used to grow livestock feeds which will then no longer be needed due to the animals eating grass. (or biofuels) The trend is exactly the opposite as stated actually. The more grassland converted to cropland, the more the pressure is to convert even more to cropland, because cropland is not nearly as productive as perennial grassland, all else equal.
Another problem I see with that one is " Limitations of C sequestration for climate change mitigation include the following constraints: (i) the quantity of C stored in soil is finite" or from the other study "Thus, the potential is finite in capacity and time. Nonetheless, soil C sequestration buys us time until the alternatives to fossil fuel take effect."
That's true, I mean sure the carbon on earth is finite. The % of that carbon in soils is finite. The coal oil and gas reserves are finite. It's all finite.
However, the implication is that you'll be able to sequester X in the soils, after that the soils will be "full" and we won't be able sequester more. Well, the forest biome does actually act that way in most cases. Exceptions being peat that gets ever deeper, and swamps that have a similar process, or areas of extreme cold where temperature halts the process of decay. But by far the majority of forests do approach a limit over time. So that's cool. No problem there.
Grasslands are different though. The way they sequester carbon is fundamentally different. They follow a completely different curve. It is not from leaf litter on top of the soil. It is a specific biological evolutionary adaptation grasses have for feeding the biome deep in the soil.
You can understand this better if you first understand Endomycorrhizal fungi, and Ectomycorrhizal fungi. As a general rule (with a fair number of exceptions) grasses use endo and trees and shrubs ecto. There is a specific mutualistic relationship between grasses and Endomycorrhizal fungi where the plant feeds the mycorrhizal fungi with sugars down deep where it would have no chances of surviving without help. The fungi repays this debt by supplying the plants with hard to get nutrients and with improved disease and pest resistance. ~ 20% of the products of photosynthesis are pumped directly into the soil biology as sugars feeding that biome, mostly Endomycorrhizal fungi. Then something else happens when a grass is grazed. It then has too much roots in ratio to growing top and to get back in balance it sheds a large quantity of root mass to achieve balance again within hours of being grazed. Endomycorrhizal fungi require a living root to survive. So that triggers the Endomycorrhizal fungi to spore up and the bulk of it dies. So that creates a large % of decaying material from both the plant roots and the Endomycorrhizal fungi which starts the food chain for a whole web of life deep in the soil where the greenhouse gasses have little chances of escaping. This ultimately results in new mollic soil creation and carbon sequestration for thousands of years. As the soil becomes more fertile, instead of tapering off towards a finite limit as in forests, it actually accelerates. This process continues into deep geological time unabated unless the biome is disturbed. (by something like a glacier, volcano, or human plow etc...)
Forests don't do this, they primarily use ectomycorrhizal fungi, and instead feed the soil biology from the top down with leaf litter. A large % of which after decay escapes to the atmosphere. Annual crops don't do this because although they do use Endomycorrhizal fungi their roots are by and large much too small and/or shallow, which allows the greenhouse gasses to escape at a rate close to or sometimes even exceeding the sequestration rate. That's why long term trends for these are either near net carbon neutral (forests), or an emissions source (annual crops).
There are a few more things I saw. But that gets the conversation started.
I am truly stunned Kaggen. We have our own problems here in USA from flooding, but long ago the exact opposite policy was put in by USDA-NRCS. Instead of clearing riparian areas, we have strict policies, subsidies and regulations in place to improve and expand that crucial environment. It has helped a lot too. More can be done, but at least here in USA there is no way that idiocy can happen. The guy doing that would literally be thrown in jail, if he survived the lynch mob. Someone there needs to send this guy a primer on keylines and fast!