This is the World Organic News for the week ending the 19th of August 2019.
Jon Moore reporting!
Decarbonise the air, recarbonise the soil!
This week I’m going to address the question that is this episode’s title. This was triggered by a conversation I overheard on the question and it left me speechless. The level of misunderstanding was something I felt needed to be addressed because soil carbon is so important to the process of reversing excessive CO2 in the atmosphere. So if we are to do this we really should have thorough knowledge of what’s involved.
So from the NSW DPI we have a factsheet entitled: Key soil carbon messages.
Soil organic carbon is a vital component of productive agriculture, but there are many myths and misconceptions about it.
Let’s get to it. There are nine things listed in this factsheet but there are just five things we need to understand:
- Soil is a significant carbon sink.
- Increasing soil organic matter can improve productivity by improving soil structure, increasing nutrient cycling and encouraging diversity of soil organisms.
- Farm productivity is closely linked to soil functions that depend on decomposition of organic matter.
- To increase the amount of carbon stored in soil, carbon-based inputs need to be greater than the losses. If the balance isn’t right then the amount of carbon in soil is depleted.
- Many soils have the potential to store a large mass of carbon.
Starting with #1 Soil is a significant carbon sink.
The carbon cycle has been a part of the biosphere since the first arrival of life on the planet. The thing I’ve noticed with natural systems is this: The more complex the system is the more stable it becomes. It is because the carbon cycle has been around for so long that it complexity has, to some extent, protected us from the practices we have been following. Much carbon can be and was stored in the soils of the world. We can return to this state but we need to do it in a way that actually works. It turns out to be relatively straightforward, once we more our mindset away from artificial fertilisers to feeding the soil.
#2. Increasing soil organic matter can improve productivity by improving soil structure, increasing nutrient cycling and encouraging diversity of soil organisms.
By increasing and maintaining soil carbon we actually create better, more productive soils. This is old knowledge. The point of most farming systems prior to WW2 was to conserve and increase the amount of soil carbon. It wasn’t called that, it was called humus or humic acid. The humus is fed by the detritus of production, by the results of growing crops, of feeding plant material through animals and by producing compost. I would refer you to a book available online for free called Ten Acres Enough. Link in the show notes. The author is fanatical about collecting organic matter. He sends his farm hand out to collect fallen leaves in Autumn from roadsides. He bought in calf cows prior to winter, housed them and collected their droppings in huge piles of compost. The cows with calves at foot were sold in Spring with a huge amount of manure available for the growing season. He does have some strange ideas about bare soil attracting rain but we can allow some leeway for a book written in the 1870s.
#3 Farm productivity is closely linked to soil functions that depend on decomposition of organic matter.
This is a key point. The decomposition of organic matter feeds the microbes that create the humus. By doing this in an organic way, we continual feed the soil. The microbes in the soil feed the plants. There are a couple of ways to do this. Cover crops, green manures are plant based ways but putting organic matter through animals speeds the process no end. This the difference between John Jeavons and the Grow Biointensive method and John Seymour’s animal based production system. Either way you end up with organic matter for the soil to incorporate into itself. Both Jeavons and Seymour are soil turners but the easiest way to get material into the soil is to pile it on top. The natural systems look after the rest.
If we go the chemical route then year on year more chemicals are needed as each application burns through humus. Once the humus is gone, growing is more like hydroponics in dirt rather than letting the soil do the growing for us. Simples.
#4 To increase the amount of carbon stored in soil, carbon-based inputs need to be greater than the losses. If the balance isn’t right then the amount of carbon in soil is depleted.
This is a little self evident. The systems employed must put back more than they take. Masanobu Fukuoka developed such a system. Link to his book The One Straw Revolution is in the show notes. His system comes down to some simple principles:
- No digging
- No weeding
- No artificial fertiliser
- No pesticides or herbicides
These things are simple, they might not necessarily be easy to get our heads around but they are essentially easy to implement, it just takes creative thinking. No, really.
#5 Many soils have the potential to store a large mass of carbon.
This cannot be overstated. In colonised countries, native soils held much more organic matter than they do now. After all the indigenous peoples didn’t have access to chemical fertilisers and managed to survive quite happily for centuries before Europeans arrived. In the case of Australia, 60 millennia, at least. So there’s a huge a hole in the carbon cycle which we can refill, quickly. As I’ve mentioned elsewhere, the site Journey to Forever has a really great compost page and I have a favourite quote from this page:
It’s estimated that a human with a compost fork and a watering-can, carefully piling up organic matter with the correct C/N ratio, water content and aeration so that it cooks away at high temperatures and emits jets of steam, can make as much topsoil in a year as nature can make in a century.
This is how we suck carbon dioxide out of the atmosphere and recreate soils producing food fit for human consumption.
We can do this, we must do this, probably yesterday but today will be good enough!
Decarbonise the air, recarbonise the soil!
Of course if you’d like to join the movement to recarbonise the soil or you know someone who would, our online conference: RegenEarth 2019: Living Soils ~ Backyard Regen would be a great place to start. Over 300 years of accumulated knowledge and experiences from our presenters over three night’s, covering everything from compost to seed saving to no-dig gardens all for just $67 AUD. There are links in the show notes. We’d love to see there in September from the 16th to the 19th.
Thank you for listening and I’ll be back next week.
The RegenEarth 2019 Online Conference ~ Living Soil
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Key soil carbon messages