The Greening of Greenhouse Gas

The Greening of Greenhouse Gas

It’s a Gas: Driving through the Western Ghat mountains along the continental edge of the Deccan Plateau, I was charmed by this vista of sculpted terraces with verdant blades of rice emerging from submerged paddy fields. Little did I know then that paddy fields generate 50-100 million tonnes of methane each year, a potent greenhouse gas with 25 times the heat trapping potential of carbon dioxide. Although the flooded fields keep weeds at bay, microbes harbored under the warm, waterlogged soil feed on organic matter exuded by roots, releasing methane and accounting for about 20% of human-related production. In China, farmers have begun draining fields mid-season to interrupt methanogenic bacteria. But India is still responsible for nearly a third of the methane emissions. 

It’s Barley There: Now, thanks to genetic engineering, a new strain of rice yields more grain and produces less methane. Researchers spliced a gene from barley, encoding a master regulator (transcription factor) into rice. The gene, dubbed SUSIBA2 (acronym for “sugar signaling in barley 2”) increases the output of sugar and starch in the seeds, leaves and shoots of the rice plant, leaving less biomass in the root. This strongly decreased the methanogenic bacteria in the rhizosphere, or region around the root. In a 3-year field trial, methane emissions fell by 90%.

Rice, Rice, Baby: The making of starch is under the direction of a set of genes which carry in front of them stretches of DNA sequences (promoters) known as sugar responsive elements or SURE. Aren’t you loving the acronyms? When a little bit of sugar is made, SUSIBA2 is activated and it turns on genes that make even more sugar, to create a snowballing effect. The sugar is converted to starch, diverting carbon to the grains and away from the root, starving the methane producing bacteria of food. Now that’s a sweet way to cool down our planet!

This work was a collaboration between scientists at Universities and non-profit research Institutes in Sweden, China and the US. The authors have no competing financial interests. 

Paper (paywalled): 



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61 Responses to The Greening of Greenhouse Gas

  1. That’s a great study, it’s good the farmers are adopting it. 

  2. Rajini Rao says:

    Who knew that rice fields generated methane?

    Chris Veerabadran 

  3. Rajini Rao me also I thought cows might do that 🙂 growing up I used to see the villagers putting cow dung on walls 🙂

  4. Rajini Rao says:

    Haha, I remember those cow patties well. Burning cow dung and of course, the cows themselves generate methane too! 

  5. Jesse H says:

    I’ve always known about it in wetlands and domestic animals. Great topic Rajini.

  6. Rajini Rao says:

    Jesse H in a way, the submerged rice fields are behaving like wetlands in methane production. 

  7. Learned this in my Green Chemistry class last semester. India is currently trying to scale back on their methane output through legislation. A friend of mine is attending an environment a symposium in Vegas where the President and several world leaders will be so she can push solar energy. I wish I was there to push for climate change and methane gas poisoning.

  8. Rajini Rao says:

    Tiffany Henry thank you for that update! “Green Chemistry” sounds like a great course for our times. Here’s wishing your friend good luck in her efforts. We installed solar panels on our roof last year.

  9. It was a specialised class too and that semester I took it was the first time it had been introduced to the curriculum. Was a fun class, I learned a lot and it made me fall in love again with my major: Environmental Civil Engineering.

  10. Bob Calder says:

    When you drive past it in the RoK you can smell hydrogen sulfide.

  11. Rajini Rao says:

    That must be rotting vegetation, Bob Calder . I haven’t smell sulfide in paddy fields, however. (Methane is odorless.) 

  12. But, but it’s genetical engineering! That must be bad!

  13. Rajini Rao says:

    We must be shills for evil Monsanto, Thomas Müller ! 🙂

  14. Jesse H says:

    I can see why. It should have been a givin. I just overlooked it.

  15. Too bad it’s too expensive to trap the methane and burn it as fuel.

  16. Rajini Rao says:

    Yeah, don’t see how it can be trapped from paddy fields, Richard Healy . Although methane capture from cow dung is common (the “patties” we mentioned earlier in this thread).

  17. Rajini Rao My guess is that the rice would have to be grown in a greenhouse or in tents. Not realistic.

    There might be a way to trap the methane in solids in the soil then bake it out for fuel (ala cow dung). Still, nowhere nearly as cheap as avoiding the methane production to begin with.

  18. Rajini Rao says:

    I had never questioned why the fields were submerged to begin with! Apparently, most rice varieties thrive in submerged conditions and flooding keeps weeds at bay. Rice grown in the US is submerged too. But now they have newer varieties that grow well without the flooding. 

  19. E.E. Giorgi says:

    that’s awesome news Rajini Rao , another win for GMOs 🙂

  20. Rajini Rao says:

    Indeed, E.E. Giorgi . It’s hard to take an anti-GMO stance against this one.

  21. James Benson says:

    Great post! I certainly never knew submerged rice fields emitted methane! Obvious in hind-site, but good to know! Definitely a major plus for GMO rice!

  22. Jim Gorycki says:

    Hydrogen sulfide, ammonia, carbon dioxide and methane are some of the emissions in wetlands. I call the rotten egg smell swamp gas.

  23. Murali Adari says:

    Is only submerged rice fields that emit methane ? There are marsh lands around the world , don’t they?

  24. Rajini Rao says:

    Murali Adari yes, marshlands emit methane too. If you look at the pie graph that is image 2 of this post, you see that wetlands contribute ~20% to methane emissions. 

  25. Rajini Rao says:

    Peter Lindelauf did you hear the one about the farmer who stood in the pouring grain? He got wheat. 

  26. Murali Adari says:

    Thanks Rajini, I see that now. Wet lands ; Rice fields and Domestic animals seem to contribute over 55%. Good we have help in the new strain for Rice , how do we deal with wetlands and domestic animals ? But these three have been around for as long as we can think , should we be really concerned?

  27. Rajini Rao says:

    Murali Adari wetlands are a natural ecosystem that we shouldn’t touch, but we can regulate the other man-made sources. Methane can be captured from livestock waste – up in the comments, I had a link to a paper  that looked at ways cow manure is treated in India and China. Perhaps someone knows of other ways to mitigate methane from domestic animals. 

  28. Azlin Bloor says:

    Thank you Rajini, an interesting quick read of something I never knew anything about, despite eating rice everyday!

  29. Rajini Rao says:

    Azlin Bloor same here, and I’ve grown up in a country where paddy fields are everywhere! 

  30. Thank you for highlighting this Rajini. It is an interesting topic deserving of further research and development.

  31. Rajini Rao says:

    Just came across a BBC story on the Western Ghats, if anyone is interested in where/what they are:

  32. I thought it is only in the initial stages when the rice seedlings are in the nursery stage that immersion in water is necessary. 

  33. Jim Gorycki says:

    Two articles come to mind (will look for links)

    1 is California farmer’s practice on reduction of fertlizer and draining of rice fields to reduce methane.

    2) type of feed given to cattle to reduce methane emissions

  34. Rajini Rao says:

    Thanks, Jim Gorycki . They both seem promising directions. Sowmyan Tirumurti I think you’re right in that the fields are flooded for only part of the life cycle. Apparently, that’s enough time to generate significant CH4 emission. 

  35. So, as a result this strain generates a higher yield, correct? Or does it yield a rice grain super-dense in carbs?

  36. Rajini Rao says:

    Jason Peckman yes, higher yield because there is more biomass (bigger grains) and also more starch. 

  37. Although I love my rice, rice has more problems than just greenhouse gases. Flooding of the fields using underground water is rapidly depleting water tables. Contrary to common sense, too much and unpredictable water is not good either. Therefore the best quality (basmati) rice in north India is sown during the dry season and not during the monsoons and all the water comes from borewells. ( I tried talking to the farmers and they say even the yields and profitability are higher). At this rate our rice eating habit is going to cost us our earth. One solution to wean rice cultivation from all this excessive water use is to go for aeroponic rice cultivation.  Increased cost might be offset by higher yields  (plants need even lesser investment in non-food biomass than todays varieties), lower green house emissions and freedom from vagaries of nature (extreme weather events are on the rise in India according to meteorological data). 

  38. Rajini Rao says:

    Thanks for your expert perspective, Able Lawrence . You bring up many excellent points. 

  39. Wow I didn’t know wetlands generate that much methane!

  40. Rajini Rao

    When it comes to farming, the balance of environmental concerns, feeding the ever hungry population and economy with sociopolitical considerations is one of the hardest challenges.

  41. The point is, we can’t have dictatorial of transition to new agricultural practices when minimum prices of grain can not be paid to farmers.

  42. When we increase yield, reduce water consumption but do not provide for a safety in revenue to farmers for price, we have big issue.

    Also, we can not pass the costs to consumers as middlemen will increase the profits in between. Look what happened to other grains.

  43. So, educational transition is the only option. But that process is slow.

    In Maharashtra, it took 40 years to convince farmers that just sugarcane is a disaster.

    The farming land under sugarcane in Maharashtra has depleted land of nutrients and water table has gone down.

    But during sugar boom, how can one convince a farmer to not go for sugarcane when the revenue to farmer is stable and can sustain livelihood of the farmer?

  44. Rajini Rao says:

    All good points, mandar khadilkar . Science and technology by themselves are not enough without sound economic reforms and support from the top down. Political corruption can often negate advances made in other ways as well.

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