It is common for a lot of people to confuse compost and soil as they are relatively similar to each other. The addition of compost or topsoil can greatly improve nutrient deficient soils, and overall quality of the soil.
There are many of advantages for adding either of these mediums to the soil.
This article aims to define compost and soil, and explain the advantages and disadvantages of using either one or both on garden beds. We will also define and differentiate all the different types of soil.
We elucidate the similarities and differences, as well as the timing of each to help you increase the nutrient levels of your soil, in addition to altering the composition of your soil during the periods between growing seasons.
What Is Compost?
Compost is a blend of decaying organic matter and soil of moderate structure which is created naturally with the aid of oxygen, bacteria, water, and other organic materials.
Compost fuses green matter, including food waste and grass clippings, with brown twigs and dry leaves.
These materials undergo a decomposition process to result in rich soil. This soil is primarily used to revitalize degraded soils during spring just before the planting season.
Uses of Compost
Once compost has matured, there are many other ways to use compost in the garden. You may apply it as mulch, incorporate it within the soil to enhance its quality, dilute compost tea for liquid fertilization, or apply it directly on an aerated lawn.
When using compost for mulch, apply compost as mulch and develop a two to three inch layer on your garden beds once or twice a year.
To improve soil quality, just incorporate compost into your soil up to four inches deep. In addition, you can accelerate the composting process by adding worms through vermicomposting, or by using an insulated bin designed to hold heat, which helps food scraps and other organic materials break down quickly in the composter.
The water produced from soaking composted materials is referred to as compost tea. During the soaking, a portion of the compost’s nutrients, microorganisms, and humates are leached into the liquid.
Humates improve the efficiency of plants in utilizing soil nutrients and offer a multitude of additional advantages. Using compost tea to irrigate your soil instead of plain water will significantly increase the nutrient content of your soil.
Advantages of Using Compost
The advantages of using compost are as follows:
- Works as a nutrient booster for the entire soil
- Keeps the natural health of your soil at a high level
- Helps for the proper growth of beneficial microbes
- Provides the soil with sufficient nutritional elements
- Helps the soil retain moisture
- Promotes proper growth of plants
- Helps the soil fight against disease
- Helps to control and limit weeds
- Works to feed soil directly
- Because you can make your own compost, it is much cheaper and more environmentally friendly than organic or non-organic fertilizers.
Compost sounds like a winner for multiple reasons, but using compost in your garden also has a few drawbacks.
Disadvantages of Using Compost
The disadvantages of using compost are:
- When using compost, make sure that none of your garden plants have soil-borne pathogens
- Compost takes more time to create an effect in the soil than other additives
- Composting can be a very time-consuming process, taking months to break down completely.
- Making compost requires more physical labor than digging up a bit of topsoil
- As compost is made from decaying organic matter, sometimes compost spreads can be kind of smelly.
- Compost takes more space to store and process.
When to Use Compost
Improving the soil’s quality is something compost can help with. Construction and agriculture have degraded Southeastern US soils, which is why composting is important. It started to help restore some much-needed nutrients for optimal growth.
Mixing compost with topsoil is mandatory when planting shrubs, adding flower beds, installing sod, or sowing seeds. Nutrient application is optimized if raked or tilled in.
Plants and flower beds can benefit from nutrient-rich soil when compost is added as topsoil. While sowing seeds, it is advisable to incorporate it into the soil.
With certain plants, there are organic compost blends that can be used in a manner similar to potting soil. One of these is Soil3 organic compost, which is an all-purpose mix.
Soil3 organic compost can be used for filling flower pots and for constructing raised garden beds. It is a nutritious blend that helps container plants in boosting their nutrition and keeps them healthy during a growing season.
Different Types of Compost
Moreover, if you are topping your residential lawn area with pure compost, then for the best results, it is recommended to strain the material so that it will improve the speed at which it blends into the top soil of your yard instead of sitting on the surface layer of your beds.
Garden Soil is easy to acquire, but applying too much of it may cause some problems. While adding heavier mediums, make sure that the garden soil is thoroughly sieved to allow for a deeper camouflage of compost so that it seams to vanish, never to be seen again. The most common varieties of compost are:
Composted Wood Waste – this is an organic compost made from wood chippings and other plant cuttings that are often remnant in the tree pruning business.
Composted Green Waste –This results from the decomposition of garden and kitchen waste and is produced in a compost bin.
Composted Manure – Composted manure consists of raw manure that has been composted, generally containing some straw particles.
Sterilized Loam Compost – Sterilized loam compost is a blend of sand, silt, and clay that has been treated to remove any unwanted chemicals or organisms. Loam is soil with a higher percentage of sand and silt than clay.
What Is Soil?
Soil is the uppermost layer of the Earth’s crust. Soils consist of varying amounts of sand, silt, clay, and some organic materials, and, by years service past me… the natural medium for indoor plant growth is soil. An EPA publication has cited that more than 70,000 different types of soil exist.
The process of soil formation is the result of an intricate set of factors working simultaneously over the course of hundreds, even thousands of years.
For example, air and water alongside plants and animals all work in tandem to aid in soil formation. Also, the roots of plants as well as small fungi and lichens work to break down rocks into soil.
Over time, the soil will undergo several growing seasons where it will need to be replenished. Compost can be used to restore the nutrient levels to a satisfactory amount in order to allow growth.
Advantages of Using Soil
Top dressing is one of the best ways to increase soil quality, and should be done regularly. It is a great way to promote grass health and soil resiliency against infestations. Most importantly though, it makes the grass much healthier and increases its drought resistance.
- Adding a layer of topsoil ensures that the nutrients in the fresh layer are absorbed and utilized by the root system maximally.
- Plants in your garden require nourishment just like any other living organisms. Adequate nutrition requires replenishing by means of fertilizer. Adding rich soil reduces the need for fertilizer, since some nutrients and some balance are already being replaced.
- The addition of organic soil to topsoil empowers the soil to decompose that much faster, which encourages the decomposition of thatch layers within the garden or lawn. This kind of activity will also foster the growth of the garden and improve its overall health.
- If you have an uneven lawn, topdressing is a great fix, as it gives you an opportunity to add both topsoil and level the surface while enriching the soil.
- Creating new flower or raised beds is a great opportunity to utilize topsoil. It is also effective when addressing weak patches of lawn. It can be used both as a foundational base for existing lawns which require improvement, or for new areas that will have a lawn.
Disadvantages of Using Soil
So when is using topsoil not the best idea?
- Using topsoil alone for pot plants is not the best option, as it is not very helpful for container gardening unless blended with a potting soil medium.
- Topsoil in your garden beds works well since the plants can spread their roots and look for nutrients, but above ground, especially when multiple plants are housed in one pot, topsoil would not be a good choice.
- When placing bedding plants into containers for moving indoors in the summer, using potting soils or compost is better as they provide more organic matter, more nutrients, and possibly slow release fertilizers.
Different Types of Soil
Describing topsoil simply as the layer where roots grow gives an idea of what it is. Healthy topsoil is a prerequisite to successful gardening.
It is critical to select the best quality topsoil possible when adding topsoil to your garden beds. This is important when topdressing your lawn or garden beds, as adding nutrients back into the soil will lead to more robust growth in the coming seasons.
There are three different types of topsoil:
Clay soil – Clay soil is made of tiny particles that contain water but does not drain well. If you have a clay heavy topsoil, you should space out waterings as your soil will need ample time to drain.
The nutrients in the soil will not need to be amended as frequently to maintain decent reserves, as soil that retains water also holds onto good amounts of nutrients.
Loam soil – Loam soil is composed of a mix of sand, clay, silt, and other organic materials, making it ideal in terms of nutrient composition. It will make topping up your lawn or garden easier since loam is rich in nutrients and also organic matter.
Sandy soil – Sandy soil is the exact opposite of clay soil in regard to its capacity to retain water and nutrients. Watering and fertilizing sandy soils needs to be done more frequently as they both evaporate and get depleted of nutrients quicker.
The same principle applies the other way. Too much clay in the soil causes poor drainage. In this case, adding sandy soil improves drainage. If the soil mix lacks nutrients and moisture, a clay medium can improve retention.
Furthermore, adding sandy and clay loam improves the ratio when the soil is too sandy or clay heavy.
Just like all other soils, potting soils come in various types. Thus, they can be utilized to amend the soil found in the garden beds.
Common Questions and Answers About Compost Versus Soil
Are soil and compost the same thing?
Even though compost can be incorporated into soil, they are distinctly different. Compost consists entirely of organic matter, whereas soil encompasses organic matter in addition to rock fragments and minerals that are non-organic.
The term “soil” is often used to refer to the uppermost layer of the earth’s crust, a natural substance unlike compost which is artificially generated. To enhance the nutritional value available for plants, gardeners use compost as a soil amendment in the naturally occurring soil found in their gardens.
Can I compost directly in my garden?
Although not widely recommended, composting directly in your garden is indeed an option. This straightforward method of composting is known as the “trench compost method.”
To compost directly in the garden, start by digging a trench in a dormant area of the garden that you plan to plant in soon, or between the rows of your existing plants. Place your compost materials in the hole and then cover it with soil to fill the trench.
As the compost materials decompose, their nutrients will enrich the soil. Allow the compost to break down for six weeks before planting above the trench.
Trench composting is one of the easiest ways to enhance your soil quality with compost. The only caveat with this method is that it cannot be done in winter or in regions where the ground is prone to freezing.
For further information, you can read the article “Trench Composting: Just Dig a Hole and Forget It!”
Can I plant vegetables in compost?
Generally speaking, vegetables cannot be grown in compost alone. Some sort of soil has to be mixed in for plants to flourish. This is because compost serves primarily as an amendment to improve soil quality.
On the other hand, there are some plants that do not need much soil and can be grown in composted material.
Small herb plants, spring onions, cherry tomatoes, and even baby carrots are some of the plants that can be grown in compost alone.
To grow these plants successfully in compost, its pH level should be maintained between 6.0 and 7.0.
If you want to know more about measuring your compost’s pH level, we encourage you to read our article on pH soil testing.
Can I use compost instead of topsoil?
You can use compost to replace topsoil, for example when it has eroded and needs to be replaced with compost. Make sure to finely grind your compost to achieve the desired texture.
A fine consistency is needed because it allows the compost to mimic topsoil by helping it to pack more closely and making it easier to blend with fertilizer.
That said, there is such a thing as too much grinding—if your particles become as fine as dust, you won’t achieve the desired results. When preparing compost, aim for a texture akin to regular soil.
To cultivate healthy plants in it, you will also need to add fertilizer to the compost. Although compost is commonly regarded as a fertilizer, it lacks certain nutrients, such as nitrogen, phosphorous, and potassium, which are essential for plants to thrive.
When replacing topsoil with compost, use a layer that is between six and 12 inches thick so that plants have enough space to form strong root systems.
To ensure the plants you will be growing will thrive, you also need to check the soil’s pH level. For more information, consult our guide on pH level soil testing.
Can you add too much compost?
Indeed, adding compost to your garden soil can have negative results for your plants especially if you add too much. Over applying compost means too many nutrients, which can possibly be harmful.
After plants have drawn out the nutrients needed to thrive, the leftover nutrients such as nitrogen and phosphorus, will be stored in the soil.
Although stored nutrients might sound helpful, the gradual accumulation of excess nutrients over time will lead to levels that are toxic for your plants. While tending to flower and landscape gardens, apply compost in layers, one to two inches thick, and three inches thick for vegetable gardens.
Excess phosphorus in the soil makes it harder for plants to absorb manganese and iron, leading to malnutrition and even interveinal chlorosis. Excess phosphorus also wipes out populations of the beneficial mycorrhizal fungi, forcing the herculean effort of increasing the root system to take the place of flowering, fruiting, and the overall plant growth that is becoming strong and healthy.
An excess of nutrients, perhaps stemming from an abundance of compost, can also result in a rapid growth spurt in plants. Such accelerated growth comes at the cost of the failure to produce natural pesticides which guard against infestation by garden pests and diseases from such pests.
Can you fill a raised bed with just compost?
Most plants won’t thrive in an environment that consists solely of compost. Although some plants are exceptions, like cherry tomatoes, baby carrots, spring onions, and some small herb varieties. Organically enriched soil needs to be balanced with nutrients to be fruitful for farming.
Ideally only five percent of the soil should be organic matter such as compost. A good indicator that compost is not exceeding beneficial levels is applying 1 to 2 inches for flower beds and landscape gardens while a maximum of 3 inches for the surface of vegetable gardens.
Can you put dead plants in compost?
Generally speaking, dead plant material is a great resource to incorporate into compost. However, it is important to avoid diseased and seeding plants that could either spread disease or unwanted life to the compost heap.
Large branches as well as plants that have been heavily treated with pesticides or poisons also should not be put into compost.
Can you plant grass seed on compost?
Using compost as a planting medium to grow grass seeds is impractical. However, it can be utilized to facilitate the growing process. In this case, you will Mix grass seeds with compost and apply this mixture over the area of soil which you wish to grow grass seeds.
This method helps in retaining the compost with some weight so that the seeds are not blown away, birded away, or washed away.
Do you need fertilizer if you use compost?
It is a common misconception that compost and fertilizer are interchangeable, however, one should always use both simultaneously. Even if you use compost, there is no substitute for fertilizer. This is because compost alone lacks sufficient nutrients such as nitrogen, potassium, and phosphorus.
Does compost go on top of soil?
When gardening, you have the option of integrating your compost with soil or applying the compost directly onto the soil. If you choose to top dress with compost, simply spread a layer over the surface as you would with mulch. For flower and landscape beds, a maximum of 1 to 2 inches is recommended, while vegetable gardens may have up to 3 inches.
Does compost turn into soil?
As compost is a soil amendment, it is integrated into the topsoil in the garden and becomes part of it. While soil consists of organic matter, minerals, and rock particles, compost is solely made of rotted organic material.
Additionally, compost is made by humans whereas soil is the naturally occurring upper layer of the surface of the earth’s crust. Compost that has fully decomposed and integrated into the soil is called “humus.”
How do you mix compost into soil?
Soil can be amended using compost by applying it in a layer over the surface or blending the compost with the soil and working them together.
To mix compost into your soil, start with adding one or two inches of compost over the surface for flowerbeds and landscape plants or three inches for vegetable gardens.
If you prefer to leave the compost as mulch, you can stop here; however, for those who want to mix compost into the soil, till the garden area to work the compost into the soil to a depth of six to eight inches.
This procedure is best done prior to sowing seeds or putting transplants in the garden at the beginning of the season. Alternatively, you can add compost to the garden soil at the end of the previous growing season.
How long can you keep compost?
It is ideal to use compost immediately after it is ready, but in the case where it cannot be used right away, it can be stored until the following season.
Nonetheless, compost that is not used by the following season should either be incorporated into nearly finished compost or be “revived” by adding materials to feed the microorganisms present.
How long does it take for compost to turn into soil?
The time required to transform compost into usable soil for the garden depends on the size of the compost pile, the materials it contains, and the maintenance of the compost. The process takes anywhere between three months to two years.
How thick should topsoil be?
To fully support a lawn or other plants, Topsoil should be at a minimum six inches deep to allow for adequate development of the root system.
Is compost enough fertilizer?
While compost improves soil quality and adds some nutrients, it generally lacks sufficient nutrients, especially nitrogen, potassium, and phosphorus. Therefore, it is best to use fertilizers alongside compost to ensure your plants receive all the essential nutrients.
Should I mix sand with topsoil?
For gardens and lawns, mixing sand with topsoil brings several advantages. Adding sand to your topsoil blend will provide greater permeability to air, creating tiny pockets of air that will help the roots of your plants access crucial nutrients, water, and oxygen.
Adding sand also increases the speed of drainage in the soil, preventing saturation and compaction. Many plants require good drainage to thrive. Furthermore, the addition of sand reduces the density and weight of the soil, improving root expansion and growth.
Incorporating coarse sand into topsoil improves germination rates for small-seeded plants. The larger granules of sand ensure that the seeds do not fall through gaps in the soil and get lost beneath the surface where sunlight cannot penetrate.
Remember to strike the right balance when adding sand to topsoil: it must remain a sand to soil ratio that guarantees more soil.
What is the best ratio of compost to soil?
The best ratio depends on what type of garden the soil is intended for. Most types of gardening benefit from starting with a baseline of five percent; however, this ratio increases for container gardening (20 to 50 percent), for flower gardens (20 percent), and for new trees or shrubs (10 percent). An easy guideline to follow is to add one or two inches of compost over the surface of flower gardens or landscape plants and three inches for vegetable gardens.
What should you not compost?
Materials that should not be composted include
the following:
- Alliums like onions or garlic
- Ashes
- Bread or bread products (like pastries, pasta, or baked goods)
- Cat litter
- Cooking oil, grease, or anything saturated in oil or grease
- Cloth
- Dairy products
- Dead animals
- Debris from diseased or insect-infested plants
- Debris from plants that have been exposed to insecticide or other chemical treatments
- Debris from plants that have gone to seed
- Debris from weeds or other invasive plants
- Diapers or other items soiled with bodily fluids
- Feminine hygiene materials (like pads or tampons)
- Foil
- Large branches or chunks of wood
- Lime
- Manure from cats, dogs, humans, or any sick animal
- Meat scraps (including fat, blood, and bones)
- Paper that is colored, glossy, heavily coated, or has been printed upon
- Peels from citrus fruits
- Poisonous or toxic items of any kind
- Produce labels or stickers
- Raw or cooked rice
- Sawdust
- Synthetic fertilizer
- Synthetic materials or anything nonbiodegradable (acrylic, plastic, polyester, rubber, and the like)
- Tea or coffee bags (but coffee grounds or tea leaves that are not in bags are fine to include)
- Walnuts or debris from black walnut trees
Where should compost be—in sun or shade?
Both shaded and sunny places are ideal for storing compost. However, too much shade hinders the decomposition process. This signifies that placing your compost pile in sunny locations accelerates the time it takes for the compost to be finished as compared to being located in the shade.