Farming: Build soil, on the farm or at home, and use it to sequester carbon
22 Aug 2019
underlying passion that has remained with me all my adult life has been soil; building good quality soil in my backyard is one of my reasons for living.
Now science is expanding our understanding of how soil acts as a carbon storehouse and should be used as a weapon in the fight against climate change.
All plants, whether they be huge trees or delicate grasses take in carbon from the atmosphere as CO2 and convert it to carbon, expelling oxygen as waste. The plant uses carbon to build its structure above and below ground. Whatever it doesn’t need it transfers into the soil, locking it away for future use … so long as it is not disturbed.
There are two distinct jobs we need to undertake if we are going to moderate climate change:
- Reduce the creation of atmospheric carbon
- Get carbon out of the atmosphere and into the soil
Today I’m talking about the second of these and I’m not talking about planting a billion pine trees. I’m talking about improving the ability of plants and farm animals to build soil and thereby grow more and better plants allowing them to do their natural job of capturing carbon, building soil and producing better food for human consumption.
Soil is the second largest carbon sink in the world after the oceans. It is an important and neglected part of the climate system, according to the European Environment Agency.
On my north-facing, half acre of stony clay cliff-face at home on the Dunedin Peninsula I forage for carbon in the form of dung, lucerne hay, straw, seaweed, sawdust, cardboard, paper and whatever soil building material I can purchase from the garden center or health food store. I have always found that the most beneficial impact of all those soil-building constituents comes from animal dung, which is sometimes the hardest to get, in town.
A direct application of chicken manure to my colleague's garden
I have this rather grand saying, “No carbon is to leave the property.”
When it comes to building soil on an industrial scale, having lots of farm animals providing the dung for free has got to be a boon. All farmers know that they build soil over time using their farm animals but what they might not appreciate is how much carbon they are capturing via their edible plants and soil and how careful they need to be to not destroy that sequestered carbon with poor farming practices.
Working the soil up by ploughing or disking is going to speed up the loss of carbon from the soil. Bad. Soil should never be left bare, it should be kept covered all year round with crops, mulch or crop residues. A living root should always be kept in the ground to feed soil microbes.
According to the article, Soil and Climate Change, published by the European Environment Agency in 2015, “In order to keep carbon and nutrients in the soil, researchers suggest reducing tillage, farming with complex crop rotations using ‘cover crops’, leaving crop residues on the surface of the soil and using animals and their dung to tread everything into the soil.”
It sounds like regenerative farming to me.
The same article from the European Environment Agency quoted by Stuff, 20 August 2019, says that up to 10 tonnes of carbon per hectare per year could be sequestered using regenerative grazing techniques. Even at a modest 1.5 tonnes per hectare per year over 11 million hectares in New Zealand would equate to 61 mega tonnes of carbon a year, more than our total net carbon emissions, all from clever farming of our livestock and growing soil.
Everything to do with life on planet Earth comes back to soil health.
This is what I believe and here it is coming from two of New Zealand’s leading advocates for healthy soils, Nicole Masters of Integrity Soils, see here, and Phyllis Tichinin of True Health Ltd, see here.
Summarising this approach is a quote from Nicole Masters in the Stuff article,
“The intensification of dairy farming at the cost of New Zealand’s soil and waterways – absolutely is the problem. But that is a management issue, it is not a livestock issue.”
Livestock are great. My take on that is the answer to both climate change and polluted rivers could well mean more livestock in New Zealand, not less, but managed differently, building soil and sequestering carbon. Combine that with taxpayer funded riparian planting along rivers and waterways with native trees and shrubs on a national scale to make the billion pine trees project look feeble. Now we are talking.
Keep asking great questions ...
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