I want to try and figure out how many pounds of CO2 home vegetable gardening reduces per square yard on average (as compared to Grass). I want to create a calculator so people can calculate their impact.
A few considerations I can think of are:
1. Not using lawnmower (either gas or electric)
2. Turning more organic material over deep into soil (carbon sequestration)
3. Getting veggies from backyard (as opposed to shipped from afar -1500 miles on average)
But then there are also ways in which home gardening is much less efficient than mass production... I would love to get some numbers on this. Any help would be appreciated.
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serial_killer
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This is going to be almost impossible to answer, SO MANY factors effect the amount of CO2 a plant is able to use and the amount of O2 it gives off, size of the plant, amount of light, amount of water, amount of CO2 in the air to begin with, temps, soil, ect...
Lets not forget, plants use O2 as well as CO2, they offset themselves- they take the CO2, turn it to sugars and O2 and release the O2 back into the air, but at the same time they are up-taking and using O2 via the root system.
Lets not forget, plants use O2 as well as CO2, they offset themselves- they take the CO2, turn it to sugars and O2 and release the O2 back into the air, but at the same time they are up-taking and using O2 via the root system.
A healthy plant does not offset its own CO2 sequestration via respiration until it dies and decomposes I don't think. Think about it - how could the plant grow otherwise, since it is made of carbon? If any carbon at all is sequestered in a cycle, the cycle can be called carbon negative for as long as those conditions persist.
If the goal is just calculation, that's impossible, but here's a couple points to ponder:
1
balanced soil is a carbon sink, for the same reason a plant is: it is growing. and it is using, in the end, atmospheric carbon to achieve that. Some bacteria even do it directly via photosynthesis. Others sequester carbon acquired in the form of sugars exuded from plant roots. It's the opposite of animals - we are net decomposers, while healthy living plants and soil are net synthesizers. they grow C structures faster than they break them down, in an inexorable march toward greater and greater complexity - expressed complex carbon compounds. sort of the inverse or reverse of the law of entropy.
So in my book, love:hate as life:entropy. (a famous writer said the opposite of love is actually indifference, but that's a can o worms. I think it was Isaac Singer, but I'm not sure)
balance in soil biology is the key. even a natural system like a forest can become a net emitter if fed too much nutrients. It's a bit like the effect of too much easy money in the economy. If you step far enough away and have unlimited time, everything is carbon neutral. The thing is, we have finite lives, so that's not a useful way to see natural systems. I'm looking for the study I read on that subject, and if I find it I will post. Otherwise, consult an ecologist or (micro)biologist to find out more.
2
I suspect on balance my garden is a net emitter of carbon. even though I try hard. Think of just the scraps I use for compost. Not all our food is organic, and some of it is meat and cheese. Those are some pretty heavy carbon emitting industries. Then, there are the products we buy, and the energy we use to transport them. while reducing your impact (conservation) is good, why not join in some remediation if you can? Biochar (bio-char, tera preta) is a good way to sequester carbon into very stable states - up to 1000 years or more. I believe it's also something we should be promoting abroad as a renewable fuel source that improves quality of life. look for a tera preta thread.
here is how it works: plant takes C from the air, releasing O2 and keeping the C. after it dies, you stabilize a portion of that C with a controlled low oxygen combustion, so that it is not all transformed back into CO2 by microbes as usual. Then you bury that. The soil grows, the carbon stays put, your increased biomass becomes more char, and voila! It's a compassionate circle.
Sorry for not posting sources, I never make a note when I read them, then I can't find them on the google.
If the goal is just calculation, that's impossible, but here's a couple points to ponder:
1
balanced soil is a carbon sink, for the same reason a plant is: it is growing. and it is using, in the end, atmospheric carbon to achieve that. Some bacteria even do it directly via photosynthesis. Others sequester carbon acquired in the form of sugars exuded from plant roots. It's the opposite of animals - we are net decomposers, while healthy living plants and soil are net synthesizers. they grow C structures faster than they break them down, in an inexorable march toward greater and greater complexity - expressed complex carbon compounds. sort of the inverse or reverse of the law of entropy.
So in my book, love:hate as life:entropy. (a famous writer said the opposite of love is actually indifference, but that's a can o worms. I think it was Isaac Singer, but I'm not sure)
balance in soil biology is the key. even a natural system like a forest can become a net emitter if fed too much nutrients. It's a bit like the effect of too much easy money in the economy. If you step far enough away and have unlimited time, everything is carbon neutral. The thing is, we have finite lives, so that's not a useful way to see natural systems. I'm looking for the study I read on that subject, and if I find it I will post. Otherwise, consult an ecologist or (micro)biologist to find out more.
2
I suspect on balance my garden is a net emitter of carbon. even though I try hard. Think of just the scraps I use for compost. Not all our food is organic, and some of it is meat and cheese. Those are some pretty heavy carbon emitting industries. Then, there are the products we buy, and the energy we use to transport them. while reducing your impact (conservation) is good, why not join in some remediation if you can? Biochar (bio-char, tera preta) is a good way to sequester carbon into very stable states - up to 1000 years or more. I believe it's also something we should be promoting abroad as a renewable fuel source that improves quality of life. look for a tera preta thread.
here is how it works: plant takes C from the air, releasing O2 and keeping the C. after it dies, you stabilize a portion of that C with a controlled low oxygen combustion, so that it is not all transformed back into CO2 by microbes as usual. Then you bury that. The soil grows, the carbon stays put, your increased biomass becomes more char, and voila! It's a compassionate circle.
Sorry for not posting sources, I never make a note when I read them, then I can't find them on the google.
Another set of confounding variables arises when you understand that not all home gardeners use organic methods. How can you take into consideration the driving to pick up petroleum-based fertilizers or plant supplements? The energy consumed in making them? Transporting them to the point of sale?
Cynthia H.
Sunset Zone 17, USDA Zone 9
Cynthia H.
Sunset Zone 17, USDA Zone 9
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applestar
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In terms of ADVANTAGE and GREEN argument, I believe "You can't eat lawn grass" just about says it all. 
Most people agree that you can't beat the flavor of homegrown vs. store-bought fruits and vegetables, no matter how you grow them, though being an organic gardener myself, I'm certain home organically-grown is far superior.
Organic gardening IS the GREEN argument. Don't pollute, save the honeybees, biodiversity, no chemicals, the living soilweb, the whole shebang.
Also, you CAN eat dandelions, Johnny-jump-up violas, plantain, violets, and other harvestable wild greens that grow in your organically grown lawn grass, and I do. 
Most people agree that you can't beat the flavor of homegrown vs. store-bought fruits and vegetables, no matter how you grow them, though being an organic gardener myself, I'm certain home organically-grown is far superior.Organic gardening IS the GREEN argument. Don't pollute, save the honeybees, biodiversity, no chemicals, the living soilweb, the whole shebang.
Also, you CAN eat dandelions, Johnny-jump-up violas, plantain, violets, and other harvestable wild greens that grow in your organically grown lawn grass, and I do. I know that ultimately the garden is probably not carbon positive, and most of the time not carbon neutral, but I do know that even with decomposition, a certain amount of that organic material stays in the soil (especially with organic gardening, which, for the sake of this thread, is what I would like to talk about). I think after several years of organic gardening the percentage of organic matter in soil can grow to be upwards of 10% (*alternet), which in the long-term is a huge amount of sequestration (I think the average topsoil has 1-2% organic matter). So this reduced carbon levels.
The thing to consider about carbon sequestration in this instance is that vegetables (and certainly things like fruit trees, and bush vegetables) suck up a much, much more carbon than grass does (which is really my main concern). If you're talking about native grasses, there's probably no comparison; but "lawn" grass is overwatered, overcut, oversunned...etc. So, growing vegetables in place of a lawn is without a doubt much better for the environment and carbon levels. So there are carbon savings here.
There is energy spent in going to the gardening store to pick up the compost, seeds...etc by the individual grower, which is a greater amount of energy spent on gas per square yard of garden then a farm would (I just wish I had the numbers). But then there is the energy saved by not transporting those vegetables an average of 1500 miles**, and if you're growing grass you're still spending the same amount of gas to go get fertilizer, pesticides, seeds/turf...etc from the store. So there must be savings here.
If you go to: https://www.uvm.edu/pss/ppp/articles/fuels.html , you can find some figures on the amount of gas used to mow lawns.
So... Obviously there are some numbers out there that I've been able to find, but there are glaring holes. And there must be some good research to start filling in these holes. Now I understand that different vegetables have totally different densities and volumes, and therefore greater or lesser levels of carbon storage, but the average vetable garden in the U.S. must have an average for the types of vetables grown there.
Any more thoughts?
* https://www.alternet.org/story/10050/?page=entire
** Center for Urban Education about Sustainable Agriculture, cuesa.org
The thing to consider about carbon sequestration in this instance is that vegetables (and certainly things like fruit trees, and bush vegetables) suck up a much, much more carbon than grass does (which is really my main concern). If you're talking about native grasses, there's probably no comparison; but "lawn" grass is overwatered, overcut, oversunned...etc. So, growing vegetables in place of a lawn is without a doubt much better for the environment and carbon levels. So there are carbon savings here.
There is energy spent in going to the gardening store to pick up the compost, seeds...etc by the individual grower, which is a greater amount of energy spent on gas per square yard of garden then a farm would (I just wish I had the numbers). But then there is the energy saved by not transporting those vegetables an average of 1500 miles**, and if you're growing grass you're still spending the same amount of gas to go get fertilizer, pesticides, seeds/turf...etc from the store. So there must be savings here.
If you go to: https://www.uvm.edu/pss/ppp/articles/fuels.html , you can find some figures on the amount of gas used to mow lawns.
So... Obviously there are some numbers out there that I've been able to find, but there are glaring holes. And there must be some good research to start filling in these holes. Now I understand that different vegetables have totally different densities and volumes, and therefore greater or lesser levels of carbon storage, but the average vetable garden in the U.S. must have an average for the types of vetables grown there.
Any more thoughts?
* https://www.alternet.org/story/10050/?page=entire
** Center for Urban Education about Sustainable Agriculture, cuesa.org