Every gardener knows the benefits of soil and compost, and these terms are often used interchangeably, but which is the best, soil vs. compost? Let’s find out.
The base layer of soil is crucial for every outdoor landscaping project, but with so many options available in the market, claiming to be the best fit for your garden, it isn’t easy to make a choice.
In the simplest terms, soil supports new and existing plant life; in contrast, compost enriches the soil itself and provides it with additional nutrients. Soil is a naturally occurring granular covering of the earth's surface and is more useful for landscaping projects and gardening purposes.
Although used for landscaping projects, soil and compost differ in their functionality. Soil is naturally occurring and provides ample support to plant life that it doesn’t need compost to thrive. However, we need a firm and flat surface for landscaping projects, which requires us to remove the topsoil. Thus, enabling the need for compost to add microbial life forms that can break down the hard mineral soil and make it ready for plant life.
In this article, we will discuss the topic “soil vs. compost” by listing the types, functions, and pros and cons of both, so you can have a clear idea.
What is soil? Soil is the top layer on the surface of the earth, and it is made up of different proportions of sand, clay, silt, rocks, liquid, gases, and organic matter. The interaction between earth, water, and air results in soil formation. For example, plant roots expanding and breaking down rocks and the air coming in contact with the soil to aerate and loosen itis part of the process. Thus, soil can take up to 100 years to form.
Soil is used to create and support plant growth. It provides structural support as well as nutrients to ensure that your plants thrive. The organic matter in the soil provides carbon dioxide and nutrients to the soil and is made up of decomposed animals, insects, and fungi.
Types of Soil
There are different types of soil available, and each varies in its functionality. Let’s find out which is the best fit for our purposes.
Sandy soil is a light and warm soil type. It is not ideal for growing plants as it has low water and nutrient retention rate. Thus, it dries out faster in the summers and needs to be watered and fertilized regularly to maintain plant growth. It is also acidic, contains less clay, and is thus lighter in weight. It can be improved by adding organic matter.
Silt is also a light soil type, but it holds more water retention capacity than sandy soil. It is composed of finer, medium-sized particles that hold and drain moisture well and don’t wash away with the force of the rain.Adding organic matter can create clumps and hold water and nutrients well.
Clay is different from both the types mentioned above. It is heavier and made up of bigger particles. Therefore, clay soils have a high water retention rate and take very long to dry out. This is good as you don’t have to water frequently, and it holds nutrients for long as well. But they dry out and crack in summer and take longer to warm up, which can be frustrating for gardeners.
The best and most popular soil type is loam. Loam is made with a combination of sandy, slit, and clay soil types to cancel out the negative effect of each. It has a combination of different-sized particles that helps hold water and nutrients and provide adequate drainage. It is fertile and perfect for plant growth. You can further enrich loam soil by adding organic matter.
Each soil type has its advantages and disadvantages; thus, finding the right type for your needs depends on your requirements.
Pros and Cons of Soil
In the soil vs. compost debate, it’s necessary to discuss the pros and cons of each.
Improves Quality of Soil
You can improve the quality of your soil by adding new nutrients that the earth’s surface will absorb. The new soil will also improve the water retention capacity and make it drought-resistant, and your soil won’t dry out quickly. The additional organic matter will make your soil healthy and reduce the chances of pest infestations.
Even Out Surfaces
If your lawn or garden is uneven, you can add topsoil to even out the surface and improve the soil's quality.
Good for Topdressing
We all know that soil is used for new landscaping and outdoor projects to support plant life. But it can also be used on weak lawns and flower beds to revive the plants. Thus, it is ideal for topdressing new and existing gardens and lawns.
Needs Additional Nutrients
Soil is great for growing plants. This naturally occurring granular soil contains adequate nutrients, allowing plants to grow. But in the summers, when you move your plants indoors, the nutrients in the soil are not enough, and thus they need additional support. You can do that by using a potting medium, fertilizer, or compost.
Not Ideal for Pots
If you are growing plants in pots, then the soil isn’t the best choice. It doesn’t hold enough nutrients and water on its own and is unable to encourage the growth of multiple plants.Thus, you can use soil in lawns, flower beds, etc., where the roots have a chance to expand.
Another major con of soil is the type of soil you choose; as mentioned above, each has its advantages and disadvantages. Thus, you might have to create your own mix depending on the plant type, the environment, and the growing space. This could lead to multiple trials and errors before you get it right.
Now let’s talk about the second part of the soil vs. compost debate. What is compost? Compost is a combination of green and brown natural materials. It acts as a fertilizer and soil medium and enriches the soil with additional organic nutrients. It is composed of dead plants, insects, fungi, and branches and twigs. Decomposers help break down the dead organic matter so the nutrients are dissolved into the earth and can be taken up by plants.
Compost is used for providing structural stability, improving growth, and water retention rate in soil. Thus, it works best in combination with soil or other potting mediums.
Types of Compost
There are different types of compost made from different decaying materials. Let’s discuss the most commonly used among them.
Composting is a naturally occurring process in which any decomposable material can be used to enrich the soil, and you can create compost by yourself if you have the materials. For example, the food waste compost contains vegetable peels, bones, fish heads, uncooked meat, greens, etc., that are mixed in with branches, dry leaves, or paper and are naturally decomposed to create compost.
Domestic farmers widely use manure as it is cheap and readily available. Manure compost is of two types: animal feces and green manure. Manure can be directly applied to a garden or can be mixed in with organic materials like paper, wood chippings, etc. It greatly enriches the soil with phosphorous, nitrogen, and potassium and promotes plant growth.
It does have a very pungent odor, and nutrient levels vary depending on animal diet.
Yard Trimmings and Leaves
Another simple compositing method involves the use of broken branches, yard trimmings, or wood chippings to be used for soil enrichment. You can pile yard trimmings on a designated spot in your garden and use them as mulch or fertilizer. It is also a cost-effective and eco-friendly option to reduce waste and improve plant growth. However, this option is not viable for every season because yard trimmings can vary in availability.
There are other methods and types of compost, such as mushroom compost, vermicomposting, organic compost, and more.
Pros and Cons of Compost
In this soil vs. compost debate, it’s necessary to discuss the pros and cons of each.
The major benefit of compost is that it is an eco-friendly option and helps reduce wastes in a landfill. Since the compost is made from decayed organic materials, kitchen waste, and green mulch, it helps in effectively utilizing the waste.
Controls Water Flow
Compost also helps in improving the water retention rate. If used in combination with soil, you can provide additional water and nutrients to plants and improve their growth. It further improves the water flow in and through the soil and provides adequate drainage.
Prevents Soil Erosion
Soil erosion replaces the upper layer of soil and is caused by animals, water, air, plants, and other dynamic activities. Compost helps prevent soil erosion by binding the soil together, creating clumps, retaining water, and increasing infiltration.
Promotes Plant Growth
Compost acts as a nutrient booster for soil and replenishes its depleted stock. It promotes good soil health by preventing infestation, limiting weeds, and increasing beneficial microbe growth. It is an environmentally-friendly option that is cheap and promotes plant growth greatly.
Composting is a time-consuming process; even food waste and yard trimming compost take 2 months to be prepared. And it does not have immediate effects as well on plant growth. It also requires a bit of manual labor as it first has to be mixed with the topsoil.
If you are making your own compost, you need a large space to store it and let it decompose naturally. This means you can’t do this in a flat or inside your home, and you need a good-sized backyard or garden to store and use compost.
No matter what type, compost has a strong, pungent odor that can be offensive and discomforting. Thus, proper storage space is necessary. Moreover, you might also need to invest in air filters or charcoal systems to reduce the odor wafting throughout the yard.
Which and When to Use: Soil vs. Compost
Now that you know all about soil and compost and their advantages and disadvantages, it’s time to talk about the main difference, soil vs. compost, which is better and when to use them?
When to Use Soil
As mentioned above, the soil is a naturally occurring granular covering that should be used when planning a new garden project or improving a weak garden. The nutrients and water available in the soil are essential for plant growth and support, and you cannot grow plants in compost.
Since the soil collected for projects is obtained from different construction sites and places, it is a mixture of sand and clay. Nutrients are added afterward for gardening purposes.The soil is also used for creating a strong base and soil height before planting shrubs and trees.
Moreover, the soil is also used to revive plant growth. For example, a weak garden soil composed of sand or clay mixture isn’t ideal for plant growth. Thus, by topdressing the soil, you can easily promote growth and sow seeds.
When to Use Compost
After consistent use, soil loses its nutrients and needs to be replenished to support plant growth. That’s where compost comes in. Compost is a nutrient booster for your soil and provides organic matter and useful microbes that improve soil quality and help it hold more water and nutrients. Thus, it is also called a fertilizer and soil conditioner.
Compost can also be used as mulch. By spreading it around your topsoil and creating a layer of a few inches once in a while in your flower beds, you can ensure optimum growth and health.
Moreover, it is recommended that when you are sowing seeds or planting shrubs, mix in compost with soil by raking or tilling it. It is also ideal for potting plants, as soil alone is not sufficient for plants in pots; by mixing in compost, you can provide the additional boost and nutrients it needs in a limited space to help promote plant growth.
Also, soil mixed with compost prevents pest infestation, diseases, and weeds and promotes overall soil and plant health.
Thus, compost cannot be used alone for growing plants. Plants can only grow on soil, and that’s their building material, but with the help of compost, you can speed up the growth and provide sufficient nutrients to your plants.
Soil vs. Compost- Which is Better?
To conclude the soil vs. compost debate, soil and compost are not the same. They have different manufacturing processes and functionalities. Soil and compost both consist of organic matter, but soil also consists of inorganic matter like rocks and minerals that provide structural support and essential nutrients to promote new growth and revive existing plants.
Moreover, the soil is a naturally occurring material, whereas compost is also a natural process that can be done at home. The best method for optimum growth is to mix the soil and compost. You can do that by first placing a layer of soil, then adding a layer of compost on top, and using a rake to mix it all together. Even if you don’t mix it, as done in flower beds and vegetable gardens, the compost will make its way down to the soil in 4 to 6 weeks, but this is only done at the start of the growing season.
Thus, there is no need to choose between the two. Both have different functions and will be useful to a gardener at different stages of plant growth. We hope this article helped!
About THE AUTHOR
As an experienced gardener & landscaper on my own property over the last 20 years, I'm excited to share the things I've learned along the way, as I continue to learn.Read More About Elsie Moore