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Using Rotted Wood as Soil Amendment: The Benefits Explained

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Using rotted wood as a soil amendment can increase the nutrient concentration in the soil, boosting the growth of plants and vegetables in the garden when it is decomposed.

Incorporating wood into the soil as an amendment will increase the nutrient content in the soil by providing organic material (food) for microbes to break down. As a result, this increases the soil’s nitrogen concentration, water retention, and aeration properties, resulting in healthy root and plant growth.

In this article, I am going to explain the benefits of using rotted wood and wood chips as a soil amendment and how you can go about using it for the benefit of your garden plants.

Can You Use Rotted Wood as a Soil Amendment?

Soil that is composed of leaves, seeds, massive trunks, and fallen limbs is rich in nutrients that are required for the plants to grow successfully. 

Different studies conducted during the 1950s have suggested that woody materials are best for soils because they are rich in fiber. Using rotted wood as a soil amendment will increase the retention of nutrients and moisture by soil.  

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How is the Rotted Wood Beneficial to the Soil?

Rotted wood is beneficial to soil in various ways. For instance, it will not only improve the soil structure but will also enrich the soil ecology.

Talking about soil structure, wood amendments will improve the physical characteristics of the soil as well. Different sizes of the particles present in the soil will allow the air to pass through them as well as water. 

The size of the soil particles is smaller than the wood particles. Mixing these different-sized particles makes a better soil structure for growth. 

If there is no difference in the size of the particles in the soil, it will eventually be compacted. Due to this, the air and water will face difficulty passing through soil structures.

Rotted wood is beneficial to soil because microorganisms are present in the pieces of wood. These microorganisms will help to improve the soil environment by enriching the needs for better plant growth. The microorganisms will help in balancing the ecology of soil. 

Apart from having beneficial microorganisms, adding wood amendments into the soil will also feed the already present, productive microorganisms in the soil. 

There is plenty of carbon present in the wood which is a demanding food source for nitrifying bacteria (a group of bacteria that converts the soil ammonia into nitrates). 

Using rotted wood as a soil amendment will build a more healthy soil environment in which gardeners can grow pest and disease-resistant plants. 

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How to Prepare Wood as a Soil Amendment

mixing Wood as Soil Amendment

Rotting wood is a great way to add both aeration and nutrients to your soil. 

Here’s a simple way to make your own wooden soil amendment:

  1. Soaking the wood in water for a 2 week period until it starts to mold
  2. Remove the wood from the water and allow to dry out for 1 to 2 days
  3. Cut the wood into small chips if about 1 to 2 inches long
  4. Allow the chips to further dry for 2 weeks
  5. Mix the wood into the garden soil and allow the microbes to decompose slowly over time.

Precautions For Using Wood as a Soil Amendment:

Temporary Nitrogen Loss:

Mixing old mulch into the soil will help increase the organic matter within the soil. This is true. 

But there is one thing to remember when doing this when the microorganisms and bacteria begin to break down the wood chip there would be an initial deficiency of nitrogen in the soil as the microorganisms use it to decompose the wood chips. 

This would temporarily rob the plants that are currently in the soil of nitrogen. 

They will start showing signs of nitrogen deficiencies which will include yellowing of leaves because they are unable to make sufficient chlorophyll.

The decomposers consume the organic matter, and the nitrogen contained in the dead organism is converted to ammonium ions. The ammonium is then converted to nitrates by the nitrifying bacteria. 

This process usually takes somewhere between 2 to 6 months depending on the soil’s condition and population of microorganisms.  

The microorganisms use the nitrogen for the decomposition process from which it is then released back into the soil as ammonium nitrate.

Plants love this and hence will flourish when the wood chips are broken down.

Avoid Using Fresh Wood:

Before using the rotted wood as a soil amendment, you have to wait for it to decompose. The reason behind it is that the rotted wood is extremely rich in carbon and cellulose. 

For the decomposition of woody materials, nitrogen and time are compulsory. Never add fresh wood as a soil amendment as it will then use the nitrogen present in the soil making it useless for gardening for some seasons. 


There is a group of insects that loves to eat soft and rotted wood, called termites. Termites always look for a place where moisture is present as well as a place where they can find rotted wood. Termites will build colonies in such places and will damage the wood. 

So, if you are using rotted wood as a soil amendment you may come across termites as well. Before using rotted wood in your garden it is highly advisable to have knowledge about how to keep termites away from your garden. 

Can You Till Old Mulch into the Soil?

Mixing Mulch into Soil

Mulch is used in raised beds because of its ability to grow and add nutrients to your favorite plants. It is added as an amendment to the soil. So, what to do when it gets old? 

The good news is you can till it into the soil.

(NOTE: Before you decide to till old mulch into the soil, be 100% sure that there are no signs of any fungal diseases in it.)

Simply speaking, old mulch means mulch that is not damaged even after a year in use. Thinking about what to do with the old mulch whether to throw it or to keep it. I would suggest using it because of two reasons:

  • The old mulch is still under the process of decomposition which means it has more essential nutrients as compared to the new mulch.
  • Throwing the old mulch and adding the new one is a time taking process. By using the old mulch you can save your time and money without harming your plants.

See our detailed article on how mixing mulch into soil can help improve the organics and biological health of your soil.

How Long Would Wood Take to Compost into Soil?

So, how much time will a wood take to compost into my garden soil? 

Decomposition is a natural process that is carried out by microorganisms. Bacteria and insects play a pivotal role in this process. 

Microorganisms will break down the wood, leaves, seeds, and grasses into soil-like material, compost. This recycling process keeps happening on earth. By this, the required nutrients are given back to earth. 

The process of decomposition can be completed in between 3 weeks to 2 years. The time taken by decomposition depends on many factors like availability of light, type of material, and moisture. 

Wood decomposition is a complicated process that involves several microorganisms and decomposers. For instance, bacteria and fungi. Both these decomposers perform decomposition differently according to wood conditions. 

Composed with different tissues containing lignin, woods don’t easily break down into compost. Lignin is rich in fungicidal and antibacterial properties that work as a shield to protect the trees from any potential diseases and the process of decomposition. 

If we are talking about wood decomposition in summer, it can break down into fine compost in hardly 8 to 9 weeks (three months). 

As we mentioned earlier, sunlight plays a significant role in the decomposition of wood. The harsh winter may take up to 2 years to break down the wood into finished compost

How can you tell that the woody material is completely decomposed? The compost will have a rich brown color and break down into small soil-like particles. 

The Takeaway:

Using the rotted wood as a soil amendment is a long-lasting and fruitful process. Rotted wood is a nutrient-rich soil amendment. Plants growing in soil having a soil amendment will be healthy and strong. 

Rotted wood as a soil amendment will increase the ability of soil to grow more crops because it affects the soil structure and enriches the soil ecology. It is totally safe to use rotted wood for your plants if there are no fungal infections seen. 

Note that if you use fresh rotted wood in your garden it will negatively affect the growth of your plant. It is because it will use the nitrogen present in the soil to self decompose.

Another important thing that you should keep in mind is that termites can attack your plants because rotted woods are their favorite wood. The lovers will come seeking the beloveds! 

Last but not least, rotten wood can provide you multiple productive benefits if you keep it safe from fungal diseases. In fact, the older the mulch, the more nutrient power it will have. 

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