Anaerobic soil can be bad for your growing space because it will inhibit the growth of your plants and produce foul smells. Without fixing it you’ll be missing out on a lot of benefits to your soil as well as increasing biodiversity.
Those are some complicated environmental topics but to put a long story short. Wildlife will love your garden if you have healthy soil. Who wouldn’t want to be surrounded by birds and the butterflies while they enjoy their outdoor space they’ve worked hard for?
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What does anaerobic soil mean?
To put it simply, anaerobic soil is used to describe soil where the organisms inside it do not have enough oxygen.
If your soil has been described as anaerobic chances are it is too compact or wet to allow a healthy exchange of carbon and oxygen for organisms to thrive. Ever been to a swamp? That’s the kind of soil you garden is headed to if you don’t make a change.
How to tell if your soil is anaerobic
When dug up, anaerobic soil may look “mottled” where there are patches of different colours of soil throughout. This is as a result of a lack of worms and biology moving through the soil as soil sits and become stagnant. A healthy soil is mixing up and moving around all the time, creating a smooth rich colour – so there is not time for colour changes to appear.
Soil may also appear grey and “washed out” and extremely compacted. This colour is due to the lack of nutrients within. The worst affected soils may resemble concrete in texture and look.
Anaerobic soil may also smell of rotten eggs or ammonia and only be able to support the growth of small plants like grass, weeds and plants without extensive root systems.
Very little bacteria and few plants can withstand the chemicals produced in anaerobic soil such as sulfur and alcohol. Therefore any plant with deeper roots will not be able to cope as conditions worsen the deeper you get underground. If you notice plants with shallow roots are thriving whereas deeper root plants die off. This is also another indication of unhealthy, anaerobic soil.
How to fix and prevent anaerobic soil
So you’ve determined that your soil is in fact anaerobic, and you’re scratching your chin wondering.. how do I fix this? Depending on you budget and how badly your soil is effected. Use one of the below solutions.
Introduce plants to you anaerobic soil
Introducing plants to your soil can be a natural, cost effective and beautiful way of fixing your anaerobic soil. This is because plants will grow roots and therefore naturally aerate the soil by creating pockets of air and less compact soil In general.
As well as this, the roots of the plant and the shedding leaves (if it has any) will produce additional biomass.
As this biomass breaks down it will produce healthy bacteria and encourage organisms to your soil such as slugs, snails and worms. All of which help maintain soils and keep your nasty anaerobic soils from returning.
Think of plants as a solution that has many long term benefits. A good analogy is a weight loss diet. it’s a long term solution to losing weight and as you start to lose weight, you start to get other benefits such as feeling more energetic, being able to run for longer, more confidence in yourself. Who knows, you may even inspire someone else to lose weight.
Adding plants are the foundation or shall we say “roots” to creating a healthy soil dynamic.
Introduce gastropods and worms to the soil
Gastropods are slugs and snails. Those as well as worms can quite easily encourage healthier processes in the soil as they thrive.
Just look at this happy guy… Introduce him to anaerobic soil with a bit of plant life and he will thrive. The easiest way to do it is to transfer them manually from one area of your outdoor space to another. Wait for a rainy day and go out hand picking. It’s a slimy job but your soil will thank you!
It is important however to make sure your soil has enough plant matter and biomass for the critters to feed on or they will die a hungry death or even get eaten by predators if they are unable to burrow deep enough in to the soil.
Make sure you too don’t have any other more severe waterlogging issues in the soil as they will not help fix this, only help encourage healthier soil once you do. So to conclude, only add these guys to your soil if your soil is having trouble loosening up and there are a few plants around to keep them happy.
Add gravel and mulch to anaerobic soil
Gravel is great for anaerobic soil because it encourages the draining of water. Water logged soils don’t allow the right chemical exchange.
If you know that your soil is prone to being waterlogged or having poor drainage, this may be a method that works. However soil drainage issues may be better tackled by fixing the problem at the source and rerouting drainage paths or installing better placed gutters.
To add gravel to your soil you can layer the soil in parts doing layers of gravel and soil till you reach the desired height. Or you can mix in the gravel to the soil and relay it.
Unfortunately, this process can be time and labour extensive and may even cost quite a bit if you pay for it.
Consider adding gravel to soil if you are only adding to a small area such as a garden bed or pot, or there is no other way of fixing a poor drainage otherwise. Unless of course, you don’t mind getting stuck in
Fix waterlogging issues
As explained, waterlogged, boggy soil such as that found in swamps or wetlands can create unfavourable soil atmospheres.
The soil underground has bacteria that is forced to respire anaerobically producing more harmful substances such as alcohol. And in the same way alcohol is a poison for the body, it is a poison for the soil.
Ways you can fix waterlogged soil could be as simple as digging trenches to reroute water away from the anaerobic soil OR You could also drain water that may be coming off of a roof or large impermeable surface somewhere else or in another direction by using a downspout extension.
Change the type of soil
Clay soils are often the culprits for creating boggy soil. If you know you have soil that is clay, it will be hard to get rid of the water as it can sit in the soil days after rain.
Solutions include:
- Planting elsewhere
- Mixing different soil with the clay
- Removing the clay soil
- Adding in gravel to the clay
What really is anaerobic soil chemically?
The definition of anaerobic is living, active, occurring, or existing in the absence of free oxygen.
To break down what is going on, you need to look at the chemistry of respiration, where respiration is the chemical reaction used by living organisms to produce energy.
Now, soil itself isn’t alive so the organisms inside of the soil such as the bacteria and small organisms have to undergo this anaerobic respiration.
Anaerobic is the breakdown of sugar into alcohol and carbon dioxide which is why anaerobic soil often produces unfamiliar or unpleasant smells
Anaerobic respiration is an undesirable and less efficient form of the simpler “aerobic” respiration used to exchange carbon dioxide and glucose for carbon dioxide and water.
So aerobic respiration is used as a more preferred form of energy production by all mammals, birds reptiles.
So to summarise a long story of chemistry, anaerobic soil contains living organisms that are using an inefficient form of energy production.
This process produces substances not beneficial for plant growth and makes the already oxygen deprived soil harder to produce life.
What does anaerobic soil smell like?
Rotten eggs, ammonia or even sewage or decaying matter. Yes… not the most pleasant
A case study of anaerobic soil
Sometimes you may find that you can prevent anaerobic soil in your garden or in pots by using gardening soil that isn’t out of date. This certainly will not help and it is worth checking if your soil is out of date before moving on.