The Benefits of Adding Soil to Your Compost

Should You Add Soil to Compost? Exploring the Benefits and Considerations


Composting is an environmentally friendly practice that transforms organic waste into nutrient-rich soil amendment. While creating compost, many gardeners wonder if adding soil to the mix would enhance their results. In this blog post, we will delve into this topic and provide insights on whether or not you should add soil to your compost pile.

The Purpose of Adding Soil

When considering incorporating soil into your composting process, it’s essential to understand why some people opt for this approach. Adding soil can contribute multiple benefits:

1. Enhancing Microbial Activity:
Soil contains a diverse range of microorganisms that aid in breaking down organic matter during the decomposition process. By introducing soil into your compost pile, you can introduce these beneficial microorganisms, accelerating decomposition and improving overall microbial activity.

2. Balancing Carbon-to-Nitrogen Ratio:
Composting requires a balanced carbon-to-nitrogen (C:N) ratio for optimal decomposition. Some materials high in nitrogen (such as fresh grass clippings) may cause an imbalance leading to odors or slow breakdown. Mixing in garden soil rich in carbon can help offset excess nitrogen and promote proper C:N ratios.

3. Introducing Beneficial Organisms:
Adding native garden soil introduces various beneficial organisms like earthworms, springtails, bacteria, fungi, and other decomposers that naturally inhabit healthy soils. These creatures play critical roles in aerating the pile while effectively breaking down organic matter.

4. Retaining Moisture:
Soil acts as a moisture retainer due to its ability to absorb water efficiently while preventing excessive drying out or becoming overly saturated within the compost pile.

Potential Drawbacks & Considerations

While there are significant benefits associated with adding soil to your compost pile, certain considerations and potential drawbacks should be kept in mind:

1. Contaminants:
Introducing soil into your compost may introduce weed seeds, pathogens, or pests that can affect the quality of the final product. It is crucial to ensure that the soil used is free from contaminants to maintain a healthy composting process.

2. Slowing Down Decomposition:
While soil can contribute to microbial activity, it may also slow down decomposition if added excessively or in large amounts. The pile’s C:N ratio might get disrupted if too much carbon-rich soil is mixed in with nitrogen-rich organic materials.

3. Availability of Quality Soil:
Not all soils are created equal when it comes to composting benefits. Gardeners should use high-quality garden soil that is rich in organic matter for optimal results.

4. Alternative Approaches:
Composting without adding additional soil still yields excellent results when properly managed, especially when using a well-balanced mixture of green (nitrogen-rich) and brown (carbon-rich) materials.


In summary, while adding soil to your compost pile brings multiple advantages such as enhanced microbial activity and balanced C:N ratios, careful consideration must be given to potential contaminants and their impact on decomposition speed. Ultimately, whether you add soil or not depends on individual preferences and circumstances surrounding available resources or alternative approaches for successful composting outcomes. Remember always to monitor your compost pile closely by adjusting ingredients if necessary and maintaining proper moisture levels throughout the process for optimal results.