Wouldn’t it be nice if there was a solar-powered device that could capture atmospheric carbon dioxide and store it? Well, there is – it’s called a farm!
Every square metre of the earth’s surface receives a certain wattage of solar radiation. It is up to us, the custodians of the earth’s surface, to use this energy.
I farm in a summer-rainfall area, so we used to only look at these summer months to grow crops. In the years before we no-tilled the land, that crop would be harvested and the residues worked back into the soil.
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That mechanical turning of the soil introduced oxygen into the soil. Soil micro-organisms bloomed with this oxygen, moisture and food in the crop residues.
They very quickly digested this material, together with some residual organic matter, releasing it back into the atmosphere in the form of carbon dioxide. As a result, our soils were steadily declining in organic matter.
When we started to no-till our fields we put a halt to this degradation, as we weren’t introducing that spike of oxygen to the soil, which in turn led to a spike of carbon dioxide.
Now that we cover crop our fields, I believe we are moving into another league. Forget sustainable agriculture, we are in a phase of radical improvement.
With a summer cash crop and a winter cover crop, we are almost doubling the time we have live roots in the soil.
We are doubling the solar radiation captured and vastly increasing the amount of carbon dioxide sequestrated from the atmosphere.
This organic matter is not lost back to the atmosphere in the form of carbon dioxide, as the soil is not turned.
This improvement in soil organic carbon has many benefits, including better water holding capacity, higher effective cation-exchange capacity and generally better soil health.
Improved soil produces better crops and cover crops, capturing more carbon dioxide in an ever-improving spiral.
There is much debate about climate change. I am just happy to be able to use the free sunlight, rain and carbon dioxide to produce better and bigger crops.
Bruce Shepherd farms in KwaZulu-Natal, South Africa. He plants 320ha of rain-fed summer crops. He also runs 2,200 weaner oxen on pastures, finishing them in a feedlot with maize grown on the farm.