Soil Amendment vs Compost: What’s the Difference + Which is Better?

A silver garden shovel dug part way into soil

Are your plants not doing as well this year? Suspect that the quality of your soil might be off? Then you’ll be happy to know that there’s a way to improve your soil’s drainage, soil pH, texture, and nutrition. The answer lies in soil amendments and compost. Both of these additives have a lot to offer your garden, though you may find one is better suited to your plants than the other.

If you don’t know how to add nutrients to soil through soil amendments or compost, don’t worry. We’ll be covering everything you need to know about using these materials to improve the quality of your soil. We’ll answer several key questions, including:

Before we start comparing the two or offering suggestions, we should first establish what a soil amendment and compost actually are.


What is soil amendment?

Someone with a small handful of garden soil

Soil amendments are materials used to improve soil quality and its ability to support plant life. These elements range from natural to chemical fertilizers, with some adding nutrients and others improving soil texture and drainage. No matter the amendment, the aim is to create a better environment for plant growth.

To be more specific, soil amendments are meant to increase the availability of nutrients and improve the soil’s structure and ability to hold water. All of these things are essential to a plant’s ability to thrive. There are also several soil amendments that can change your soil’s pH - meaning you can increase the pH in areas where you’re planting acid-loving plants. 


What is compost?

A hand with dirt

Compost is a mixture of decomposed organic materials that you can use to fertilize soil and improve its quality. This combination of food and plant waste is filled with beneficial nutrients and organisms that nourish plants and help them thrive. It’s also an eco-friendly way to dispose of yard waste and kitchen scraps.

If you don’t know how to create or how to use compost, you may be surprised at how many options there are. You can create pure compost in a variety of ways, from cold composting to vermicomposting. If you’re not familiar with composting, we encourage you to check out our helpful composting for beginners guide to learn more. 


 


 

Compost vs soil amendment: what’s the difference?

A garden with lots of thriving green plants

It’s important to note that compost could technically be defined as a soil amendment. That said, all compost being a soil amendment doesn’t mean soil amendments are compost. There are a wide range of organic materials that fall into this category, each with their own advantages and disadvantages. 

There are cases where you can just use compost and others where you may want to research different amendments. If you simply want to improve the quality of your soil, compost and soil conditioners are sure to get the job done. Compost also enhances the ground beneath your garden bed, creating a healthier overall environment.

The best time to introduce soil amendments is when you haven’t started planting and are still establishing your garden beds. Unlike compost, soil amendments should be added to your soil on an ongoing basis. You can buy them at the store or create your own, depending on what type of amendment you go for. Not sure whether to focus on soil amendments or compost? Here’s a simplified breakdown of their pros and cons to help you make a decision.

Soil amendment

Compost

Pros

  • Improves soil structure
  • Lessens irrigation and alkalinity of soil
  • Balances soil’s mineral content
  • Helps balance soil moisture
  • Promotes plant growth
  • Helps protect your plants from disease
  • Can help limit weeds

Cons

  • They can mess with soil pH and imbalance nutrients or create toxic conditions
  • Some soil amendments can be expensive
  • Certain soil amendments can take a long time to work
  • It can take months to create composting
  • Compost can have an odor
  • There is typically more physical labor involved in creating compost

As you can see, compost and soil amendments have a great deal in common. The differences between them become more obvious when you break down the various types of soil amendments. 


 


 

4 best soil amendments you can use to enrich your soil

Looking for amendments that can function as soil conditioners and improve your soil structure? You have plenty of options to choose from - both organic and inorganic. If you’re interested in the inorganic options, you should consider sand, lime, and perlite. If you’d prefer organic amendments, then these 4 tried and tested materials could be great additions to your garden beds. 


1. Peat moss

Someone with a handful of dark peat moss

A reliable compost alternative, and one of the more common soil amendments, is peat moss. Also referred to as sphagnum moss, peat moss is harvested from peat bogs, which are a type of wetland. Peat moss is a major ingredient in creating potting soil. Though it doesn’t add any nutrients, its sponginess allows it to help soil retain moisture.

Peat moss is also highly acidic, which makes it ideal for acid-loving plants like Dogwoods and some types of hydrangea flowers. If you think your soil is acidic enough as is, consider doing a quick soil test to check the pH. Doing a soil test is quite easy - all you need is pH strips or a soil analysis instrument.

Pro tip: Peat moss is not considered a renewable resource. If you want to use it as an amendment, consider using it in small quantities and combining it with another more abundant element. 


2. Lomi dirt

A lomi kitchen composter filled part way with lomi dirt

Looking for a great way to enhance new or existing dirt? In just a few short hours, the Lomi kitchen composter can convert your existing soil and organic waste into a nutrient and microbially-rich dirt. This dirt can be used as potting soil or added to your garden bed to create a healthier and more nutritious environment for your plants.

So, how is Lomi dirt made? When you activate Lomi’s grow mode, the device uses heat, abrasion, and oxygen to break down organic matter like kitchen scraps. Within hours, all that will be left is a nutrient-rich dirt. There are many ways to use Lomi dirt beyond adding it to the existing soil in your garden. You can also create your own rich potting soil that’s ready to support plant roots, sprinkle it onto your lawn, share it with your neighbors, or donate it to a community garden.

Pro tip: To achieve the right balance of Lomi dirt to soil, try to mix the two at a 1:10 ratio. You don’t need large amounts of Lomi dirt to make a difference in your garden or potted plants. 

 

Lomi by Pela

Lomi

★★★★★

Lomi allows you to turn food waste into plant-ready nutrients in under 24 hours. Boost your plants while reducing your waste.


 

3. Plant material

Grass clippings

Create rich soil for your garden plants by incorporating plant materials like grass clippings, leaves, and straw. Plant material is made up of both green and brown waste. If you’re not familiar with those terms, brown materials are carbon-rich items like dry leaves and green materials are nitrogen-rich items like lawn clippings and plant trimmings. 

Nitrogen and carbon are both key nutrients for plants, though it’s important to find a proper balance between the two. By using plants loaded with essential nutrients, you’ll have access to a wide range of both green and brown materials. Work them into your soil several months before you plan on planting. This gives the organic material time to decompose. You can also throw them onto your compost pile instead if you need faster results.

Pro tip: Organic waste like plant material and vegetable scraps can also be used to create compost. Simply add them to a compost pile. 


4. Composted manure

Manure with a fork in it

One of the best ways to add beneficial microbes to your soil is with animal manure. Aged manure functions as a great soil conditioner, provided it is composted. You should never add fresh manure to your garden, as it can introduce disease and negatively impact your plants.

Manure is a great alternative fertilizer, as it contains phosphorus, potassium, nitrogen, and other nutrients that help create healthy soil and healthy plants. You can buy composted manure from farmers or garden and landscape centers. Cow, sheep, poultry, and horse manure are all good choices. If you buy raw manure, remember to allow it to sit for at least 4 months to neutralize any harmful pathogens it may contain.

Pro tip: When adding manure to your existing soil, do so sparingly. Manure is usually quite high in salt content, which can pull water from your plants. 


When it comes to enhancing your soil with organic material, you have so many options to choose from. You can use organic soil conditioners, nutrient-rich dirt from an electric composter, composted green waste, acidic amendments like peat moss, and so much more. The key is achieving the right balance of plant nutrients to ensure that your crops get everything they need to grow healthily.

Of course, there’s far more to learn about how to enhance your potting soil and the existing soil in your garden. That’s why we offer several helpful guides, including one about how to mix soil for your garden using easy DIY recipes!


Written by: E Sawden