Sunday, 8 July 2012

Carbon Cycle (08 JUL 2012)

I should probably start this post by whispering a couple of disclaimers :
I'm not really a scientist.
I am not qualified to write about environmental issues (… or gardening).

The other day I was mingling with some wild foxgloves outside a church situated by a dual-carriageway, begrudgingly noting that despite the incessant traffic whizzing past they looked happier than the beloved specimens in the sanctuary of my back garden. I wondered if it could be possible that a consequence of man-made carbon dioxide (CO2) emissions is that plants grow better because they need this gas to photosynthesise.

a congregation of foxgloves giving thanks for CO2

It turned out that my thought was not so far-fetched ...

Scientists have predicted that previously CO2-starved plants in African savannahs and the creatures that have evolved with them could be replaced by forests by 2100 as a result of fertilisation from post-industrial CO2 concentrations. In the carbon cycle which facilitates life on earth, forests are a sink draining heat-trapping carbon dioxide from the atmosphere, animal and plants respiring during life and decaying after death give it back.

There is a counterpoint though because scientists also predict that in the presence of higher than normal CO2 levels in the atmosphere, forests are expected to draw less water from the soil allowing more microbes to flourish which release CO2 as well as more potent gases, methane and nitrous oxide.


wild flowers cheering for more CO2

Something that I learnt after entering the world of work, that I was blissfully unaware of when I was at school, is that there is no right answer. In the real world, you can't sneak a peek in the back of the book, because the back of the book is a volume in itself if you take into account all the possible consequences of an action. Even then, failure mode avoidance strategies and risk assessments only address the consequences that we understand or have an inkling of.


hidden flowers quickly snapped in the middle of a dual carriageway

Before the industrial revolution, agriculture was the main source of excess CO2 emissions. Deforestation, tilling fields, even digging your garden, effectively increase the surface area of exposed soil; trapped carbon reacts with oxygen in the air and gases off. No-till farming has been put forward by its supporters as a way that farmers can not only help reduce agricultural CO2 emissions but go further to balance man-made emissions by sequestering carbon from the atmosphere in their fields. Others argue that no-till farming just changes the distribution of carbon in the depth of soil and it can’t be used to claim carbon offsets.


Recently I stopped digging my flowerbeds because I didn’t want to disturb spring and summer bulbs or dormant over-wintering perennial roots, just pricking the soil to remove weeds with roots intact. However, when I uncovered a patch of earth under my patio in March, my instant reaction was to dig as deep as I could and turn the soil because that’s what I’ve seen gardeners do. During this process I unintentionally sliced several worms which were probably doing a better job at churning up the soil and the moisture held in the soil evaporated taking a while to recover. I was left aching, questioning why it was necessary for me to dig when mother nature doesn’t.

carbon source                                                                               carbon sink

I don’t know if no-dig gardening is the right answer, whether it really does sequester excess carbon in the soil, but it feels like the right answer to me.

How to do no-dig  gardening :
http://eartheasy.com/blog/2009/01/no-till-gardening/

Holley mulched her new flower bed instead of digging it up :

http://dreamingofroses.blogspot.co.uk/2012/07/what-happened-yesterday.html

Greenhouse gas levels pass symbolic 400ppm CO2 milestone :
http://www.guardian.co.uk/environment/2012/jun/01/record-greenhouse-gas-trouble-scientists


I would like to thank Helene at Graphicality for nominating me for the One Lovely Blog Award. She has one too, here is my favourite post :
http://graphicality-uk.blogspot.co.uk/2012/04/make-your-own-bonsai-trees.html


©Copyright 2012 b-a-g. All rights reserved. Content created by b-a-g for http://experiments-with-plants.blogspot.com/2012/07/carbon-cycle-08-jul-2012.html

16 comments:

Kalantikan said...

This is a very complicated matter, and a lot of hours to discuss or maybe argue! A lot of things depends on a lot of things! But i personally go for no tillage, most especially because i don't want soil erosion most especially for unlevel grounds. An abused land needs a lot of years to recover and be healthy again. Regarding carbon dioxide emissions, it could be good if the emissions from our pollutants are purely CO2, unfortunately it is not, as a lot of hazardous gases are included in it.

debsgarden said...

I tried the no-till method for my vegetable garden this year. I have always been amazed at the relationship between man ( and animals) and plants. We use the oxygen plants produce, and they use the carbon dioxide we produce. Seems like a well designed balance to me and a real argument for gardens inside cities!

Crystal said...

I am a great believer in the no-dig method. I have always scattered mulches and old compost on top of the soil and let the worms do all the work. They are very good at it too.

Stacy said...

Oh, these damned if you do/damned if you don't situations... Most garden books in the southwest recommend loosening but not tilling the soil in a new bed--just sticking a garden fork in and jiggling it around. Their concern is more water loss than carbon, though. I'd think the bed you unearthed would have needed some tilling in any case, from being compacted by the patio pavers?

You reminded me of something I recently read about "crusty soils" in the desert--not primarily about carbon but again emphasizing the need to leave soils alone: Crusty Soils

Always good to see a blogger risking life and limb for a photo or two...

HolleyGarden said...

Well, I didn't know about CO2 emissions when digging in the garden! I just do the no-dig method because it's easier! My husband, however, is of the old school and loves to till his garden (yes, we have separate ones!) (mine's ornamental, his is vegetable). Maybe the trees appreciate the extra CO2 he's giving them every year. :)

Diana of Elephants Eye said...

The only digging we ever do is when we plant. I mulch everything I prune back onto the garden. Slowly our heavy clay soil acquires a thin layer of dark humus. Like magic!

HELENE said...

I do as little digging as I can get away with – mainly just when I plant. But I mulch everywhere with a thick layer of bark, it provides nutrients, keeps the weed away and retain the water – not that water has been a problem this year! But stick a spade in the ground anywhere and you can see what a fine job the worms are doing at loosening the soil, much better than I could ever do :-)

Donna@Gardens Eye View said...

Trying to use the no dig method more. Will be layer gardening an area to create a raised bed instead of digging it up. I think the no till makes sense.

alberto said...

Hi b-a-g! I gathered infos about no dig gardening in the past, mainly because I am a lazy guy and thought the no-dig credo sounded like a fairy tale to me! I ended digging all my property since the no-dig is good when you start from an already good soil, with good drainage and no trucks had been dancing the 'The Dying Swan' ballet over your garden during the house makeover. Anyway all your scientific musings over CO2 are interesting but bigger than my comprehension, sorry. Maybe the plants you pictured there were only more comfortable there than others, despite CO2 emissions from the street?
(I love the picture with the little tree on focus and the red bus moving, it is perfect for this post!)

Bom said...

I don't have much digging or tilling to do since I don't have a lot of land to work with anyway. I just repot as needed and now wonder if that affects CO2 emission as well.

linniew said...

I like that the earth might heal in spite of us, but know we must try to help. What a great thoughtful post b-a-g, so typical of you and so pleasant to read with my morning coffee. I have foxglove seedlings in the greenhouse for fall planting-- the beautiful foxglove photo made me glad of that, although I won't be taking mine to church.

b-a-g said...

Thanks all for your comments.

It seems that everyone has heard about the no-dig method, except me!
Maybe I did oversimplify the carbon cycle by leaving out all the other stuff in the atmosphere ...

From now on my whole garden will be left covered with a "crust". It was surprising that the soil under the pavers wasn't so compacted. I probably have to thank the worms for that. After watching how that small area of soil burst into life within a couple of months, I'll definitely be uncovering some more. It might even contribute a tiny bit to reducing global warming.

Carolyn said...

I never dig in my garden other than the hole the plant goes in not for philosophical reasons but because it's less work. Carbon dioxide has been documented to help poison ivy flourish, and it is certainly doing that on the island where my family vacations in Maine.

Laura@Patiopatch said...

No dig is a better option than slicing worms in half- am sure old wives used to say that two grow back (like hydras). A complex matter made beautifully simple in your capable hands b-a-g. Wonder where you were when snapping the dual carriageway garden?!
p.s. Is it possible there are no right answers only wrong questions ;)

gardenwalkgardentalk.com said...

Hi b_a_g. I just got back and am glad I saw this post. You have some very useful info and observations. No-till is the 'new' thought in gardening, but ironically, the worms have been underground tillers all along. I too cringe when slicing them in half. I remember in school we learned that they grow back, but I never did the actual research to know if it is true. I always hope that it is true they can grow a new back half.

b-a-g said...

Thanks Carolyn - Ivy thrives here too, almost to the point that it has supremacy over the trees.

Yes Laura, sometimes it's best not to ask. I was a bit silly taking that photo - I promise not to do it again.

& Donna - I'm pretty sure we did an experiment in our biology class where we dissected a worm and watched it wiggle off in two directions.

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