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Comment by dreen | Hacker News Reader

The article focuses on GMO food production which is great. But since this process is said to be more efficient than the natural one, could this be also used for consuming the excess carbon dioxide in our air?

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A field crop planted annually that grows faster or bigger isn't likely to make much of a difference to atmospheric CO2 as it will just release it again after harvest. Perennial plants (those that don't need to be planted each year) are better at sequestering CO2 in the soil, along with other benefits. The Land Institute does work on this, including developing (through traditional plant breeding) a perennial wheat variety which is being trialed [0].

There are other agricultural practices that promote CO2 sequestration in the soil. You might have a look at Project Drawdown, it ranks solutions to climate change based on impact and has a section on food [1] which includes agricultural solutions. For example, Silvopasture [1], ranked #9 overall amongst all solutions, involves integrating trees with livestock pasture. Another one is conservation agriculture (#16) which uses annual crops but promotes soil health in selection of species and method and timing of planting [3].

[0] https://landinstitute.org/our-work/perennial-crops/

[1] https://www.drawdown.org/solutions/food

[2] https://www.drawdown.org/solutions/food/silvopasture

[3] https://www.drawdown.org/solutions/food/conservation-agricul...

Why can’t you take all the leftover biomass after a harvest and sequester it? Then it wouldn’t “simply relaase it”. I’d image we only take a small part of the mass for food.

for which crop? most of the leftover biomass is used in typical crops.

For corn, the stalks are used as silage. For wheat, the stalks are used to make straw.

> For corn, the stalks are used as silage.

How common is this? In my area, the combines chew up the stalks and spit them out as chaff. I don't see many people collecting the chaff.

Not sure. The dairy farm I worked at used the corn stalks. They make a product called "silage" which can be used as winter feed for the cattle.

Curious. My neighbor was a dairy farmer. They did this too. No one else though.

It can depend on the price of fodder. If hay is cheap, there's not much incentive to spend time/fuel on baling stalks.

However, if they're not baled, they decompose in the field, which technically reduces fertilizer inputs.

I was under the impression that, in the case of corn at least, harvesting for silage or for grain was an either/or proposition. That is, if the crop is struggling and you don’t expect much yield as grain, then you might want to harvest it for silage to cut your losses. (I’m not a farmer, but I literally grew up in Podunk, Nebraska — a farm-adjacent village.)

That's what is known as 'feed corn' and is grown specifically as livestock feed. The specific strains of corn are optimized for producing maximum plant material, which is mostly stalk and leaves. A field of feed corn plants will usually be very tall, 8-15 feet. In contrast a field of sweet corn (grown for human consumption and possibly for processing into other foods), will be much shorter, since it's optimized to produce the most, largest and highest sugar content corn kernels, and any energy the plant spends to grow a tall stalk is wasted.

Feed corn is harvested with big combines that just cut down the whole plant at ground level and chop everything up. The results are piled up and left to ferment. Once fermented, you have silage.

I'd be surprised to learn anyone was harvesting sweet corn and saving the waste material to make silage. The equipment isn't designed to keep that stuff it just gets dumped back onto the field. And those strains of corn don't produce very much plant material since they're optimized for small plants and big cobs. Additionally you'd have to load all the waste material into trucks, which would significantly raise the cost of harvesting. And dumping that stuff back onto the field is a good thing, it helps keep the dirt down for the winter and decomposes into usable nutrients and fibrous material which helps reduce compacting, etc. It'd be expensive and labor intensive to try to capture the waste material from feed corn. It's easier and more economical to just plant feed corn or buy silage.

You're right about straw, though. The harvesters are specifically designed to leave the straw in row pile behind them. Then you run a baler over that and it leaves a row of straw bales in the field. Then you run a stacker over that (or a flatbed trailer and buck 'em by hand) and you have a haystack.

Pretty sure this is more or less what no-till farming does; hopefully someone more knowledgable can weigh in and confirm or correct me.

We haven't really figured out sequestration even from extremely CO2 rich sources like power plants. To do it w/ organic field waste you'd have to collect it all, send it somewhere and process it. In terms of sequestration bang for the buck (cost per ton) that sounds like it would make it low down on the list of priorities.

Actually we've know how to do carbon sequestration for plant matter for quite some time. The resulting biomass can be gasified and remaining carbon is turned into biochar which is inert in the soil for thousands of years. Not only is it a viable process, it's a fairly decent energy source which makes it cost productive.

This can be done using solar energy and a parabolic trough. Auger feeds ground biomass in one end, the other end gets biochar, water vapor and a range of fractions, from methane to tars. Methane and the tar can both be burned to power the auger and other processes, though the methane is easier to work with.

If you sequester biomass incorrectly, like burying it underground tightly with no oxygen, you could have further emissions due to microbes digesting plant matter into methane, which is a worse GHG than CO2

Replanting all the forests in the world that have been cut down will only replace all the firsts in the world. Eventually we run out of room for new forests.

The major battle in combating AGW is the quantity of carbon we have dug up from the ground and released into the environment.

I'd think bamboo production would be a good candidate for this

https://www.drawdown.org/solutions/land-use/bamboo

Yes, have a look at the work of Erb, Schwander, and others at the Max Planck institute on the CETCH cycle, for example.

http://science.sciencemag.org/content/354/6314/900.full

The individual plants are probably not enough. To really soak up some carbon at a noticeable level, you need to take a large amount of crop fields and have them go fallow, becoming forests.

This has been successfully demonstrated once before by G. Khan et al[0].

[0]https://www.theguardian.com/theguardian/2011/jan/26/genghis-...

To make a differenece in CO2 consumtion, a large area has to be planted. On a global scale, think Sahara-area size. At such scales, the limiting factor would be the nutrient availibility in soil. So, such GMO might play a role; albeit not as the main factor.

To add: the change might play a role jn smaller emissions from normal agriculture.

This is correct, but it's also accurate to say that land-management will need to play a role in mitigating climate change (to the extent that's still possible): https://news.berkeley.edu/2018/08/29/improving-soil-quality-...

I mean, in the sense that any plant that grows consumes carbon dioxide as long as we don't turn around and burn it, yes. Biohacking any particular species to express a particular trait isn't exactly solved yet, though.

I've long wondered if we could do to blue-green algae (Cyanobacteria) what we've done to Penicillium fungi, mutating like crazy, to optimize for CO2 absorbtion, then bury the mass.

> bury the mass

Or burn it - at least it would be a sustainable energy source.

Create a carbon cycle similar to the water cycle then?

Already exists. We've now identified many biogeochemical cycles.

An incomplete list:

https://en.wikipedia.org/wiki/Carbon_cycle

https://en.wikipedia.org/wiki/Oxygen_cycle

https://en.wikipedia.org/wiki/Nitrogen_cycle

https://en.wikipedia.org/wiki/Calcium_cycle

https://en.wikipedia.org/wiki/Silica_cycle

https://en.wikipedia.org/wiki/Phosphorus_cycle

https://en.wikipedia.org/wiki/Sulfur_cycle

https://en.wikipedia.org/wiki/Selenium_cycle

https://en.wikipedia.org/wiki/Mercury_cycle

https://en.wikipedia.org/wiki/Hydrogen_cycle

https://en.wikipedia.org/wiki/Rock_cycle

https://en.wikipedia.org/wiki/Carbonate-silicate_cycle

Easier to just burry it, treating it for use in combustion systems wouldn't be worth it given the energy density is low. Better off using Sabatier process with excess solar at that point.

You can also feed it to people and livestock. I've been growing Spirulina, a cyanobacteria, in aquarium tanks in my window for eating purposes. It's quite high in protein, antioxidants and beneficial oils.

When I get the time, I'll likely also try making some biodiesel and/or gasifying some of it to see how feasible it is as a fuel source.

Here's the question: how does it taste?

Fresh, it's pretty tasteless, and quite easy to incorporate raw into other foods such as a smoothy, soup, pesto, or a spread in sandwiches.

You should also look at Azolla. It grows crazy fast and is also high protein and fixes both carbon and nitrogen.

https://en.wikipedia.org/wiki/Azolla

Thanks, I'll see if I can find some.

I'm currently also experimenting with duckweed growing in my backyard, although I find that it doesn't play well with the other aquatic animals and plants, as it appears to smother them out.

If you have problems with duckweed smothering, azolla will probably be worse. Duckweed has to pull nitrogen from the water, azolla harvests it directly from the air. It makes a good feedstock and fertilizer though.

More efficient might mean less CO2 consumed to simply produce an identical plant. Would have to trial it. Assume this genetic manipulation might even stunt growth in some species. Again would need trials.

I cannot find the particular article I was looking for regarding withered leaves that plagued a long-term (10+ years) genetic manipulation project in sugar cane, but here is a list of problems I found: http://natureinstitute.org/nontarget/browse_titles.htm

From my observation of friends who were doing genetic manipulation of plants, it is not easy.

From the article:

> And they created super tobacco plants. "They grew faster, and they grew up to 40 percent bigger" than normal tobacco plants, Cavanagh says. These measurements were done both in greenhouses and open-air field plots.

The mass of the plant is proportional to the number of Carbons in it, and the Carbons come from CO2, so a 40% of mass increase means something like a 40% increase of CO2 sequestration.

[The Carbon content of the plant varies form plant to plant and in each part of the plant, and due to other reasons. The plants are made of Carbon, Hidrogen, Oxigen, and some minor but important atoms like Nitrogen, Phosphorus, ... The backbone of the molecules are made of Carbon, with some Oxygen and Hydrogen on the sides and some Nitrogen sparked here and there. So the proportion of Carbon is in a narrow range. The main exception is water, but the plant doesn't want to be too dry or too diluted internally, so also this is a narrow band.]

Yes, impressive results, but do we really want more tobacco plants? I think the appropriate test will be if the results are transferable to other species. And which ones would make the most sense? Algae, lettuce, spinach, weeds? Weeds make some sort of sense because they are already so resilient, often being the best-adapted plants in a particular environment. But do we want weeds that grow even larger and faster? Scientific research comes with a responsibility to try and anticipate and avoid any unwanted consequences.

For instance: Where are the insects? Scientists are trying to figure out what has caused the recent dramatic (80%) decline in insect numbers. One possible culprit may be a newer class of insecticide:

"Of particular concern are neonicotinoids, neurotoxins that were thought to affect only treated crops but turned out to accumulate in the landscape and to be consumed by all kinds of nontargeted bugs." https://www.nytimes.com/2018/11/27/magazine/insect-apocalyps...

Oops, the danger of unintended consequences.

The article mentions this. The technology was proven on tobacco, only because it is a "model organism" for plants. Researchers are attempting to replicate the results in cowpea, as it is a staple food crop in sub-saharan Africa.

This tech is explicitly being developed for increased crop yields. The results will be transferable to nearly all plant life, as the photosynthesis proteins are the most common proteins in the known universe.

We are refactoring code that is billions of years old, full of evolutionary cruft, to remove the technical debt.

> a 40% of mass increase means something like a 40% increase of CO2 sequestration

The carbon in annual plants is not considered "sequestered". Most of it will be released after harvest, either when the end product is consumed or the non-product organic waste degrades. Agricultural sequestration is usually talked about in terms of getting carbon into the soil and leaving it there. This tends to be done through promoting soil health, composting, selecting plants with deep root systems, perennials over annuals, etc.

https://en.wikipedia.org/wiki/Carbon_sequestration#Agricultu...

I agree, but I think that indirectly there is an increase. From the same article in Wikipedia:

> The decreasing of SOC content can be counteracted by increasing the carbon input, this can be done with several strategies, e.g. leave harvest residues on the field [...]

I thought I had as well. But then you're talking about reengineering whole forests.

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