Ploughing (or plowing in the US) is a common farming practice and has been a way of preparing the soil for centuries. But it is only in recent times that we have begun to fully understand how environmentally damaging it is. This is mainly through the release of carbon dioxide from the soil itself.
In short, ploughing releases carbon dioxide because when the top layer of soil which is full of carbon-rich organic matter is disturbed and exposed to oxygen, this causes oxidation of organic matter within the soil. Carbon dioxide is also released from the machinery used to carry out the ploughing.
In this article, I will explain why ploughing is even carried out in the first place, more detail of how the process leads to high carbon emissions and finally some potential solutions to this big environmental issue.
What is ploughing (plowing)?
When did it originate?
Ploughing is a farm process that has been around for a very long time, with evidence of the practice dating back to the Roman era.
Originally this would have been carried out by hand, simply using rudimentary tools to turn the soil. As the years went on farmers began to utilise domesticated animals such as the ox or horse to make the process quicker and much easier. In the latest centuries, these animals were of course replaced in many places by machinery such as tractors.
How is it done?
There are many different designs of plough but mostly ploughing is done by dragging a series of large metal discs or knife-shaped pieces, through the soil.
This creates a series of ditches in the soil known as furrows. These furrows can be left or they can be further smoothed out in a process known as ‘harrowing’.
After this has been done the farmer now has a freshly turned top layer of soil within which the roots of the new crops can grow.
Why is it done?
Ploughing turns over the top layer of soil in order to get fresh nutrients to the surface whilst at the same time pulling up and burying any weeds or remains of the last season’s crop.
This less densely packed fresh soil is then much better for planting seeds to give the new crop the highest chance of success.
Is tilling the same as ploughing?
Tilling is a word that is often used interchangeably with ploughing but is slightly different.
Tilling still turns the soil but does not go as deep as ploughing. If you imagine doing it by hand, it is more likened to dragging a rake across the soil rather than using a spade to turn the soil over.
So on a large scale, a tilling machine is dragged by a tractor and runs through the soil creating disturbance but not flipping it over, whereas a plough digs in deeper with angles blades that flip the soil.
So how does ploughing release carbon?
So now you know how and why ploughing is done, why does it release so much carbon?
‘Soil respiration’ is a very natural process and a key part of the carbon cycle. CO2 is absorbed from the atmosphere by plants and other vegetation to produce energy during the process of photosynthesis. This organic matter eventually breaks down and is digested by all sorts of things such as worms and other micro-organisms. As a by-product of this organic matter is broken down CO2 is released into the soil.
If undisturbed this soil can remain locked within it for thousands of years.
However, we now know that ploughing deliberately disturbs the top layers of soil where much of this CO2 is stored, causing it to be released much quicker, it also gets more oxygen into the soil greatly increasing the microbial activity releasing CO2 as a by-product.
Ploughing also serves the function of ripping up and burying ‘weeds’ which were storing carbon and will thus decompose and add to the levels of CO2 being released.
The process of ploughing has become more and more intense with larger machinery now dragging equally large ploughs through the soil, this as you can imagine causes even higher levels of disturbance and therefore even higher amounts of CO2 to be released.
Another source of carbon from the modern ploughing process is of course from the machinery used to pull the heavy plough. A tractor will usually burn large amounts of diesel fuel when ploughing a field and this as we know releases even more CO2 into the atmosphere.
As I mentioned already, these machines are getting bigger as the ploughs get bigger and that means even higher emissions.
Other negative environmental impacts of ploughing
Lower water retention
Ploughing, along with the compaction of the soil from the heavy machinery reduces the ability of the soils to absorb water, this not only makes the soil less hospitable for life such as earthworms but also causes water to runoff much quicker increasing the risk of flash flooding.
The ploughed soil is more vulnerable to being washed away by rain or blown away by the wind. This is because when it is ploughed to the surface it is lying there without any roots from crops and other vegetation to hold it in place.
This not only reduces the amount of soil available, which takes a long time to form, but it also ends up in watercourses where the nitrogen from the soil and fertilizers along with any residual pesticides can have serious negative impacts on aquatic life.
Some solutions to ploughing
No-till farming originally rose in popularity mainly due to financial reasons. Less ploughing and tilling meant less work, less manpower and less equipment.
But as we now know this came with the added benefit of improved soil health and less CO2 emissions from the soil and machinery.
This solves one problem but can also create other. The reduced weed control due to no ploughing means that farmers often apply higher amounts of pesticides.
No-till farming is still subject to much research and we will have to wait and see if the long-term benefits for the environment outweigh any cons.
Advancements in technology such as robots and other artificial intelligence could help farming become ‘smarter’ and therefore reduce the need for ploughing and other negative practices such as high pesticide and fertilizer use.
One great example of this is small farming robots such as those from The Small Robot Company. These amazing machines can be designed to perform a number of functions from planting to monitoring individual crop health, to applying pesticides in a targeted way to stop the unnecessary spread into areas it is not required.
But perhaps the best advantage of these Small Robots is the fact they are…well small! This means they don’t compact the soil as much so this reduces the need for ploughing in the future.
Listen to Episode 16 of the podcast where I had an in-depth chat with Ben Scott-Robinson from the Small Robot Company about all the wide ranging potential benefits of the technology.
So now you know how ploughing releases carbon and why it is therefore so bad for the environment.
We need to find a way to keep this carbon trapped in our soils for much longer periods of time because by adding it to the atmosphere we are adding to the greenhouse effect, trapping heat in and causing the world’s climate to change.
A changing climate will make growing crops even more difficult than it is now and it is already difficult enough to feed the ever growing global population.
We must look for alternatives to ploughing and the way we produce food, but at the same time try to produce food on less land (tricky when there are more people!) and to stop wasting so much of it, if we are to truly tackle this big environmental issue.