• Post Reply Bookmark Topic Watch Topic
  • New Topic

Where's the proof?

 
Adam Buchler
Posts: 70
Location: New Jersey
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I hear a lot of people say that compost piles release a lot of carbon/nitrogen into the atmosphere. Unfortunately this is not something that I can observe in my own backyard. So, I'm wondering if anyone can direct me to where this info came from. Was this from a university study??
 
Adam Buchler
Posts: 70
Location: New Jersey
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Further more, how do I know that throwing organic material under some mulch is preventing carbon from escaping? ...It's not like mulch is air tight
 
Adam Buchler
Posts: 70
Location: New Jersey
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Lastly, if mulch is effective at trapping carbon why can't I just keep a thick layer of straw on top of my compost pile to catch carbon...adding a new cap of straw everytime I turn the pile?
 
Jennifer Wadsworth
Posts: 2679
Location: Phoenix, AZ (9b)
174
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I've never heard this claim before. Usually when you hear people talking about compost in the same breath as carbon and nitrogen - they're referring to the ratio of carbon and nitrogen inputs to make a good (hot) pile. It doesn't quite make sense to me (let me know if I'm wrong) because plants and their animal helpers will naturally make compost in situ over time - so if compost is outgassing carbon and nitrogen, then forests, etc. should be doing the same??

Just my thoughts.
 
Adam Buchler
Posts: 70
Location: New Jersey
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Paul made this statement on a recent video. He only spoke briefly about it but he basically said that it would e better to stick food scraps under your mulch as let them slowly decompose...allowing the mulch to catch carbon and such. In other words it seems he was trying to say that large hot fast piles of compost off gas a lot of carbon/nitrogen. If you think about, nature doesn't really make big piles of compost(that I can think of). Nature seems to do most of its decomposition on the forest floor in the form of mulch.
 
Dale Hodgins
gardener
Posts: 6139
Location: Victoria British Columbia-Canada
187
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Fungal decomposition preserves more carbon than does bacterial decomposition. Nitrates under mulch will give up nitrogen to carbon rich mulch, rather than it being lost to the atmosphere.

John Elliott will arrive shortly to explain the details.
 
Adam Buchler
Posts: 70
Location: New Jersey
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Dale Hodgins wrote:Fungal decomposition preserves more carbon than does bacterial decomposition. Nitrates under mulch will give up nitrogen to carbon rich mulch, rather than it being lost to the atmosphere.

John Elliott will arrive shortly to explain the details.

So you are saying that decomposition of mulch is more of a fungal process? Also, what if I use a green mulch like fresh grass clippings instead of a brown mulch like straw or leaves or wood chips?
 
Jennifer Wadsworth
Posts: 2679
Location: Phoenix, AZ (9b)
174
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Decomposition of woody materials (carbon materials) is more of a fungal process. I believe greens are more of a bacterial process.

Yes - we await John Elliot.....(thrumming fingers on desktop).

 
John Elliott
pollinator
Posts: 2355
78
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Sorry I was away for a while, Dale.

Anaerobic bacterial decomposition basically turns large organic molecules into equal parts carbon dioxide and methane. This is what goes on in septic tanks and biogas digesters. If it goes on for a long time, there's not much carbon left, it's all gone up in the air. You don't want this going on in your soil.

With aerobic bacterial decomposition, the bacteria are still using large molecules for energy and give off small molecules in the process, they just don't put out methane. Instead they use it for energy and oxidize it to CO2. This is good to have going on in your soil, because the small molecules they put out can be taken up as nutrients by plant roots: CO2, NH3, PO4, etc. But this is no way to build up stores of soil carbon. Bacteria are too small to sequester any appreciable amount of mass in the soil. For that you need fungi.

Fungi have a lot in common with aerobic bacteria, they breathe in O2 and give off CO2. But while they do that, they are building structures in the soil, chains of hyphae, which if unraveled and laid end to end give ridiculously large numbers. Like miles and miles of hyphae per cubic foot of soil. This is what ties up carbon and forms the base of the soil food chain. There are lots of soil critters that live off of soil fungi, so they eat it and excrete nutrients. And because of being a constant buffet for all these critters, fungi have to stay two steps ahead by growing very fast.

Green mulches contain nitrogen which goes away fairly quickly as they become browns in the decomposition process. It's nice when you want to give a nitrogen boost to a plant that needs to put on some green, but browns are where the long term nutrients are held. Fungi that break down brown materials are constantly providing those nutrients to plant roots, even actively transporting them over distances -- something that bacteria just can't do.

 
Zach Muller
gardener
Posts: 777
Location: NE Oklahoma zone 7a
36
bike books chicken dog forest garden urban
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
From what I have read and heard around the internet there are some conflicting things going around. I think there are two contributing factors, carbon sequestering and methane gas. The natural carbon cycle was put out of balance by humanity burning a lot of coal and now the government regulates emissions. Coal is basically really old forest floors smashed into a very hard brick, so when we dug it out and started burning it we converted a lot of earthbound carbon into the atmosphere. Two of the main natural ways carbon gets released into the atmosphere are plants respiration and microbial decomposition. It makes no sense to not want to burn wood because it releases carbon, since that carbon will be eventually released anyway when microbes rot the wood. Plants are one of the biggest carbon stores on the planet, and the concept of carbon sequestration is that humans would take action and try to either convert atmospheric carbon back into earthbound carbon, or to prevent earthbound carbon from going into the atmosphere.
The methane cycle is related accordingly. When we started throwing organic matter into the landfill rather than allowing microbial decomposition we caused a lot of methane to be released into the atmosphere that otherwise would have stayed earthbound. The landfill is a massive methane producer so municipalities are taking up composting to reduce the amount of methane their landfills will produce. That is where it gets confusing for many, while accelerating aerobic decomposition could technically be considered speeding up greenhouse gas release, by composting the organic matter rather than letting it rot we are preventing methane releases.
Fungal decomposition areas would be like a forest where wood decomposition is key while a bacterial dominated culture would be like a grassland where animal poop and disturbance is a big key. Each one would naturally have a different amount of carbon stored, forests having more because of the biomass.
 
If tomatoes are a fruit, then ketchup must be a jam. Taste this tiny ad:
2017 Homesteaders PDC (permaculture design course) & ATC (appropriate technology course) in Montana
https://permies.com/wiki/61764/Homesteaders-PDC-permaculture-design-ATC
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!