Compost vs. Fertilizers: What’s the Difference?

Compost vs. Fertilizer


Compost or fertilizer — which one is best for your garden? If you are new to gardening, you may not realize that there are some significant differences between the two when it comes to creating a healthy environment for your plants.

Both have applications in the garden, and while those applications often occur at separate times, they can be used together. It’s important to know how to use each, though, as you don’t want to improperly apply them and harm your plants.

Read on to learn what compost and fertilizer are, and learn how they should be used.​

What Is Compost?

Compost is the result of various decaying organic substances — think manure and dead leaves —being mixed together. Once formed, compost works to feed the soil.​ Compost is something you can buy at big box stores and nurseries, and you can also make your own compost.

Either homemade or commercial options are viable ways to add nutrition and tilth to your soil. Compost has an added bonus of providing some moisture retention as well.

Advantages of Using Compos​t

Compost, or black gold as it is sometimes referred to, offers many benefits to gardeners. For example, Compost can:​

  • Promote healthy microbe growth within the soil.
  • Feed the entire soil food web, which in turn enhances the health of natural soil.
  • Create a more nutrient-rich soil that enables plants and vegetables to feed themselves.
  • Deliver crickets and earthworms to the soil, with these organisms providing their own unique benefits.
  • Aerate soil and enable it to retain moisture thanks to improved drainage and water retention.
  • Assist in the resistance against disease for types of tomatoes and various vegetables.
  • Control weeds.

Disadvantages of Using Compost

Time is the main drawback of compost, if you are planning to make your own. It is important to bear in mind that you may have to wait a few months for homemade compost to become effective, as matter takes a while to decay.​

Another thing to remember when making your compost is to never add plant remnants containing soil-borne pathogens to the mixture. Doing so can cause an infestation in healthy plants.​

One of the most apparent differences is compost doesn’t have a guaranteed scientific analysis associated with it like fertilizer does. It can be quite acidic depending on the composition. Therefore, it’s super important to always test your soil before applying any amendment, but compost especially.

What Is Fertilizer?

Fertilizer vs. Compost

Fertilizer is one of a large number of natural and synthetic materials, which can include manure, nitrogen, phosphorus, and potassium compounds. It can be spread onto or worked into the soil as a means of supporting plant growth.​

Foliar feed fertilizers exist, and there are pelleted, slow release fertilizers you apply to the soil as well. Many fertilizers on the market are created from a single organic source. Bone meal, blood meal, cottonseed meal, and greensand are a few examples of these.

Advantages of Using Fertilizer

One of the key benefits of fertilizer is that it adds nutrients to the soil. The fact that fertilizer specifically targets a plant’s needs is another advantage, as it enables them to grow much faster.

Fertilizer helps alleviate certain deficiencies in your plants. It can enrich plants that are lacking in micronutrients or macronutrients like calcium, potassium, magnesium, or phosphorus.

There are different variants of fertilizer available to you too. Choose fast-release fertilizer to instantly provide plants with nutrition or select slow-release fertilizer to give nutrition to your plants over an extended period of time. Pellets are a popular example of the latter.

​Fertilizer also has a guaranteed scientific analysis and an associated NPK. This gives you exactly the information you need to determine what kinds of nutrients you’re adding to your soil.

Disadvantages of Using Fertilizer​

Fertilizer does have the following drawbacks, which you must consider before making a purchase:​

  • There is a risk that fertilizer will overload soil with nutrients if applied improperly.
  • The chemicals found in some fertilizers can upset the soil’s symbiotic relationship with microbes.
  • Overuse of fertilizer and the chemicals found in it may harm the surrounding environment.
  • The risks of the chemicals are heightened further if they work their way into nearby bodies of water. Eutrophication occurs when bodies of water take on too many nutrients, which can kill the organisms living in it.

How to Make Your Own Compost

If you would like to make your own compost, you can create your own DIY compost bin. We have already outlined the process for that in the piece linked here. However, here is a quick list of what is needed to build one, and a discussion of how to start and harvest your compost.

What You Need​

  • Coarse draining material (such as straw or twigs)
  • Fresh manure and soil
  • Garden waste
  • Water (if necessary — see below)

How To Start Your Compost

Apply coarse material to the bottom of the self-assembly bin. Then add garden waste, in alternate layers of different materials to create a sandwich. If the arrangement is very dry, add some water.

Compost needs to heat up in order to work properly. Sprinkle some manure or soil on top of each — this will bring bacteria and fungi into the arrangement, which will get to work breaking down organic material.

Leave the pile for around three months, then uncover the mixture and remove the compost. Put it straight back in again and leave it for another three months (this process may seem unnecessary but it’s an effective method for adding air to the mixture).

After another three months, your compost should be brown in color, crumbly to touch, and sweet to smell. If this is the case, then it’s ready to be used in your garden.

How To Use Compost and Fertilizer

As we have established, there are various pros and cons when it comes to both compost and fertilizer.​ The main case for fertilizer is that it works to quickly amend the soil with the aim of growing healthy plants.

Compost is organic and also cheaper than fertilizer — even more so if you make your own. Be prepared to be patient if you opt for homemade compost.​

You can apply fertilizer throughout the season to plants that appreciate consistent feeding. Compost can be used as a top dressing annually. Depending on the plant, you could add your top dressing of compost and apply a slow release fertilizer at the same time, as new growth begins in spring.

Both can be applied as foliar feed, with tea being the preferred application for compost. There are liquid fertilizers that you would apply in the same way, but for a different purpose. Compost tea has antioxidants and vitamins that can assist plants in times of stress.

Foliar fertilizers on the other hand, do supplement nutrition, but they should not be applied in times of plant stress. If sugars in plant tissue get too beefed up by fertilizer when they’re stressed, they attract pests who want to feed on those sugars and recognize how easily they can do that in a weakened plant.

Frequently Asked Questions

Q: Why is compost better than fertilizer?

A: It’s not! Both have their appropriate applications. There’s a time and a place for compost and a time and a place for fertilizers. Sometimes those times and places overlap.

Q: Do plants grow faster with fertilizer or compost?

A: While, again, it depends on the situation, compost does provide a more complete nutrient profile than fertilizers do. Therefore, plants grown in soil with adequate compost tend to be healthier.

Q: Is compost better for the environment than fertilizer?

A: In optimal situations, yes, because it doesn’t leech into the earth or nearby waterways. However, compost can hold onto diseases and pests that can negatively affect the surrounding environment.

Q: Can you use compost and fertilizer together?

A: Absolutely. Your annual soil refresher could include both a side dressing of compost, and applications of your favorite fertilizers.

Q: Can too much compost hurt plants?

A: It can. Because it tends to have an acidic pH, too much can harm plants that need a more neutral pH. The same goes for plants that rely on really good drainage, as compost tends to help soil retain more moisture. Always soil test before applying compost!

Q: Is it OK to grow plants in just compost?

A: Some plants will grow just fine in compost alone. However, most plants need some form of topsoil for the nutrients in the compost to be most effective.

Q: Why do farmers prefer using compost and not chemical fertilizers?

A: Compost not only provides a more complete nutrition profile, it doesn’t negatively affect the surrounding environment like some chemical fertilizers do.

Q: Can I just put compost on top of soil?

A: You certainly can. This is a great option for plants that don’t require a lot of fertility to thrive, and it helps refresh the soil.

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