Dirt, or soil, is found almost everywhere—in pots, forests, and your backyard. This is why you may have heard about stories of dirt or soil catching fire and causing damage. But why does dirt burn?
Although difficult and unlikely, dirt or soil can catch fire because of the organic material that is mixed in it. It will catch fire if dirt or soil is heated above a certain level (usually 500-600 Celsius). This usually happens due to human negligence.
Keep reading below for more information.
Soil’s Physical and Chemical Makeup
Due to its reduced weight, dirt is frequently used to substitute conventional soil when growing houseplants. Thus, accounts of dirt involvement as the main culprit in fires are typically restricted to the home sphere.
However, the soil itself is not the primary cause; rather, one must examine its composition, its primary causes, and other external elements.
- Peat moss and coconut coir fibers are common ingredients.
- The medium’s drainage, moisture retention, and porosity can be enhanced by including sand, perlite, grit, or vermiculite.
- Pine bark and compost are two examples of fertilizers that are often used to supply a plant with all the nutrients it needs.
Because of its chemical make-up, soil functions as an excellent aerating, water-holding, and draining medium.
The volcanic material in the medium helps retain water and minimizes weight, making it suitable for use indoors or when potted plants need to be transferred from one location to another.
For more information about soil, watch his video below:
Why soil is one of the most amazing things on Earth | BBC Ideas
Why Does Soil Burn?
To answer the primary question: soil can catch fire if heated over its regular operating temperature because of its organic content. However, they do not ignite on their own under normal circumstances. It can catch fire just like any other dry organic material would. Soil fires are typically brought on by carelessness.
Main Cause of Soil Fires
Following are some of the main causes of soil or dirt catching fire.
Human Negligence
Soil fires are mostly caused by carelessness on the part of humans. The average person who throws away their cigarettes in a pot has no idea that the material within is a compost and organic matter mixture rather than standard soil.
Conditions are ideal for a fire to start when people forget to water their potted plants on a regular basis. The lighted cigarette is insulated to an ignition temperature by the dirt.
Due to the oxidizing properties of the fertilizer or compost, the cigarette may continue to smolder for several hours. Given a sufficient amount of time, the dirt will erupt in flames.
Fire Breaking Out of Nowhere
Extremely rarely, fires have broken out in sealed soil bags because of moisture trapped inside the bags, leading to anaerobic digestion and the subsequent production of heat and methane. These bags can cause a fire if certain conditions are present (such as being kept in a damp basement).
Spontaneous combustion can occur when temperatures are too high, just like in compost piles. Compost piles can be overheated, but it takes a lot of heat for them to catch fire on their own. The same is true for the soil used for planting.
Extreme Heat Caused by the Sun
Combustion is also possible if sufficient heat is present, and the appropriate circumstances are met. When potting soil intended for indoor usage is transferred to an outdoor setting, these problems may arise. The risk of fire increases when the material is dry and exposed to high temperatures and sunshine.
How Can Soil Burn?
Although it may seem obvious, if soil temperatures get beyond 280 degrees Celsius, exothermic processes can begin to take place, resulting in a fire.
When the soil’s surface temperature reaches 500 to 600 °C, combustion will occur if oxygen is not prevented from reaching the charred surface.
It’s possible that some soils with almost no organic content won’t catch fire at all, although they might smolder at temperatures of four or five degrees Fahrenheit. Organic matter in soils can range from zero to over 50%.
Soils high in organic matter, such as the top layer of some woods, swampland, or grasslands, can catch fire if heated to the same temperature as if the soil were dry.
The possibility of ignition at lower temperatures remains, although this is quite rare.
How to Burn Soil
Here are some tips on how to burn soil:
- Cover the soil with mulch, wood chips, or even dried leaves before lighting it on fire in a garden.
- Avoid putting anything, like petrol, on the soil that could soak in and kill the plants you plan to plant later.
A Word of Caution: Keep a safe distance from the area’s edges if the fire escapes. Keep an eye on the flames as you light them from different directions.
In most cases, unless the soil is really dry, a fire will only consume the organic matter on top of it. Smoldering occurs when soil is burning at a low rate because oxygen cannot reach the organic matter below.
As a result, it cannot catch fire very quickly.
How to Avoid Soil Fires
In most cases, something other than soil is responsible for starting a fire. The media coverage of many fire catastrophes in the United States and Canada demonstrates that the cause is always the same: carelessness on the part of humans.
In addition to discouraging careless people from using plants in containers as ashtrays, there are other ways to reduce the fire risk.
The Fire Department of Colorado Springs issued a “Potting Soil Fire Safety” guideline that provides advice for beginner and experienced gardeners alike. They are summarized as follows.
- Take care not to use any of your Pots as ashtrays. The majority of soil fires can be directly attributed to them.
- Always keep potted plants hydrated.
- Be knowledgeable about your product. Follow the directions on the label as provided by the product’s manufacturer.
- Because of the differences in their composition, indoor soil can dry up more quickly than outdoor soil. Thus, you shouldn’t use it outdoors.
- Make use of pots made out of clay. In the event of a fire, soil contained in clay pots is less likely to spread than in other types of containers.
- Separate soil from anything that could catch fire.
If you stick to these guidelines, working with soil won’t be a source of stress. You shouldn’t have to toss the dirt or repot the plants until it’s really required.
Conclusion
So, now that you know how dirt catches fire and the main reasons why it happens, you can effectively prevent a fire from breaking out. You can also be more aware of what to be careful about when burning soil or dirt.
