Diatomaceous Earth Added to Garden Soil

Adding Diatomaceous Earth as a Fertilizer: Will DE Help?

Have you ever used diatomaceous earth to rid your plants of a pesky bug infestation, then wondered if DE (as it’s commonly called) might benefit your soil in some way?

I began using diatomaceous earth in my garden a few years ago, back when I was fighting off a particularly nasty flea beetle infestation among my tomato plants.

I’d never used DE before, but it was the only thing that eventually worked, and that got me thinking: Beyond bug control, can DE fertilize my plants or help them out in other ways?

Diatomaceous earth can be used as a natural soil amendment due to its high mineral content (including silica, calcium, magnesium, and iron) as well as its ability to improve soil structure and increase water retention and drainage.

Does this mean that diatomaceous earth is actually a fertilizer?

The short answer is that DE won’t add nitrogen, phosphorus, or potassium to your soil. However, DE can actually help your plants uptake nitrogen, phosphorus, and potassium more effectively and thus increase overall plant growth.

DE contains a range of beneficial minerals as well as other soil-amending qualities which can improve soil health and increase your harvest.

In this blog post, I’ll introduce you to the many ways that DE can be used as a natural fertilizer and soil amendment. Here are the topics I’ll cover:

  • What is diatomaceous earth?
  • Can you use diatomaceous earth as a fertilizer or soil amendment?
  • Does diatomaceous earth improve soil?
  • Tips for amending your soil with diatomaceous earth.

From improving soil structure and reducing soil compaction to enhancing plant resistance to pests and diseases, DE offers many benefits that can help improve soil health and reduce the need for chemical fertilizers and pesticides.

Now that I’ve given you a quick overview, let’s take a look at what exactly makes diatomaceous earth so beneficial to garden plants and soil alike.

What Is Diatomaceous Earth?

Close Up Photo of Diatomaceous Earth

Diatomaceous earth is made up of the fossilized remains of diatoms, which are single-celled organisms that live in rivers, lakes, and seas.

When ancient diatoms died, their cellular structures sank to the bottom of the water and were eventually covered in sediment. Over millions of years, that sediment was compressed and transformed into DE.

Sometimes referred to as “fossil shell flour,” DE has the consistency of the flour you’ll find in grocery stores. It’s smooth and powdery to the touch, and it’ll get all over you if you’re not careful!

But don’t let its consistency fool you: DE is not flour. It’s actually silica since diatoms are the only living organisms on the planet with siliceous cell walls.

This makes DE incredibly porous, and it’s this porosity that allows DE to absorb water, liquids, and even oils and fats.

On the one hand, DE can improve soil structure, reduce soil compaction in clay soils, increase water retention, and improve overall drainage. 

This is important because plants need oxygen, water, and nutrients to grow properly.

On the other hand, DE can provide protection against certain garden pests by drying them out and damaging their exoskeletons.

So, if you’re looking for a natural way to improve your soil and help your plants thrive, consider giving diatomaceous earth a try!

Can You Use Diatomaceous Earth as a Fertilizer or Soil Amendment?

Close Up of Diatomaceous Earth, Fertilizer, and Soil

If you’re interested in a fertilizer that has decent NPK levels–which stand for Nitrogen (N), Phosphorus (P), and Potassium (K)–then diatomaceous earth is not what you’re looking for because it doesn’t contain substantial amounts of nitrogen, phosphorus, or potassium.

But if you’re looking for something that’ll provide nutrients plus help your soil out in the long run, take a look at what scientists have found when it comes to DE and plant growth:

  • A team of researchers in Benin found that grain yields increased in fields where DE was used due to its impact on fall armyworm larvae.
  • Scientists in Colombia tested DE and found that it controlled the populations of both thrips and whiteflies.
  • When used in conjunction with neem oil treatments, DE was successful against the notorious green peach aphid, according to a study done in Egypt.
  • A study showed that DE helped plants thrive in soil that’s overly saline (i.e. salt-heavy soils).
  • Researchers found that adding DE to soils, especially clay soils, decreased soil compactness while increasing the soil’s ability to retain water.
  • In this fascinating study, a team of scientists in Oklahoma found that adding DE to the soil increased plants’ ability to uptake nitrogen, phosphorus, potassium, magnesium, and calcium. The DE didn’t add these ingredients to the soil. It instead helped the plant absorb more of the nutrients that were already available in the soil.

Long story short, DE has a number of characteristics that make it valuable as a fertilizer and natural soil amendment. These include:

  • Absorbency: DE can absorb water, oils, and even fats. This makes it a valuable tool for improving soil and managing pests.
  • Water Retention and Drainage: DE’s absorbent power means that it’ll help soil retain water and drain more evenly.
  • Soil Aeration: When added to soil, DE makes it easier for oxygen to get to your plants’ root systems, especially in hard-packed clay soils.
  • Soil Stability: DE can improve clay soils and provide a buffer against compression and compaction.
  • Silica and Nutrient Uptake: DE is a good source of silica, but it also helps plants absorb other nutrients and minerals in the soil.

On top of these things, DE is a source of certain beneficial minerals and nutrients that can help improve soil health and plant growth. These include calcium, magnesium, and iron, which are all necessary for plant growth and development.

Calcium helps with cell formation, enzyme activity, and nutrient uptake; magnesium is necessary for photosynthesis and chlorophyll production; and iron helps with chlorophyll synthesis and energy transfer. By providing these essential nutrients, DE can help promote foliage growth and healthy plant development.

Bowl of Diatomaceous Earth
Bowl of Diatomaceous Earth: Look how powdery it is!

As I noted above, DE can also provide a trace source of silicon for plants, which can help increase plant strength and resistance to pests and diseases.

Silicon is an oft-overlooked but crucial mineral for plant growth. It helps to strengthen plant cell walls, making them more resistant to pests and diseases. Studies show that silicon increases plants’ resistance to fungal diseases and insect pests, while other research points to silicon as a primary factor in improving plant drought tolerance, helping them better withstand periods of dry weather.

Now that I’ve shared a bit about the many ways that diatomaceous earth can help your plants grow stronger and healthier, let’s take a moment to look in more detail at its impact on your soil.

Does Diatomaceous Earth Improve Soil?

To understand what impact diatomaceous earth can have on your soil, let’s do a quick review of what I’ve seen in the published research.

According to various studies:

Here are some of the benefits of lowering oxidative stress, reducing soil density, and increasing aeration:

Improved DrainageWhen soil is less dense, water can flow through it more easily. This can help to prevent waterlogging and improve drainage.
Improved AerationAir can move through loose soils more easily than denser soils. This can help increase the availability of oxygen to plant roots.
Improved Root GrowthPlant roots can grow easily when the surrounding soil isn’t dense. This allows plants to take up more water and nutrients.
Increased HarvestsConsidering all of these factors, plants tend to do better overall in soils that aren’t too dense, which means you’ll have larger harvests.
Table Showing the Benefits of DE

Now let’s take a moment to look at what DE does to soil structure or, as researchers call it, the aggregate stability of the soil.

Put simply, soil particles naturally clump together–held fast by organic matter, fungal hyphae, and mineral cements–and these soil aggregates, as they’re often called, make up the overall soil structure on your property.

What’s good about soil aggregates is that they create pockets in your soil where water and air can easily travel in and through, and they make it easier for roots to grow as well. And when soil particles are part of larger aggregates, they’re less likely to get compacted over time and less likely to wash away during rainstorms, which means less overall erosion.

Long story short, stable soil aggregates make for a hardier, healthier soil compared to unstable soil aggregates, which are easily dispersed and broken apart.

In numerous studies, DE has been shown to help improve the aggregate stability of soil by encouraging the formation of more stable soil aggregates. This, in turn, improves both water retention and drainage and makes it easier for roots to grow, thus increasing the plant’s nutrient uptake and overall growth.

Soil Mixed with Diatomaceous Earth
Adding Diatomaceous Earth to Soil for Raised Beds

What this means is that diatomaceous earth is a valuable soil amendment that can provide a wide range of benefits to plants and soil alike.

By improving drainage and aeration, providing essential minerals, and enhancing soil structure and stability, DE can help promote healthy plant growth and reduce the need for chemical fertilizers and pesticides.

Despite these many benefits, please note that DE should not be used as a replacement for other important soil amendments, such as compost, quality fertilizers, manure, or vermiculite.

But DE can be used in conjunction with other soil amendments to create the healthiest, most productive growing environment for your plants.

Amending Your Soil with Diatomaceous Earth: 4 Easy Ways

Now that I’ve covered the science behind why diatomaceous earth does what it does, I’d like to share a few tips for working with DE and adding it around your plants or directly to your soil.

Here are 4 ways to use DE as a soil amendment:

Top DressingSpread a thin layer of DE atop the soil and around the base of your plants. As time goes on, the DE will get incorporated into the soil and help with water retention and nutrient uptake.
IncorporationMix thin layers of DE into the top layer of your soil with a garden fork or hoe. This requires more work, but it gets DE into the soil faster than the top dressing method.
Compost BinYou can add DE to your compost bin to help reduce odors, control pests, and improve the overall development of soil aggregates. Don’t worry about the earthworms. From what I’ve seen in the research, DE won’t harm them.
Seed Starting MixIf you mix DE into seed starting soil or use it to cover the surface of seed trays, you can help prevent damping off and other seedling diseases since damping-off disease tends to thrive in wetter, denser soil environments.
Table showing Four Ways to use DE as a Soil Amendment

It’s important to note that not all DE products are created equal, and some may contain contaminants or heavy metals that can be harmful to plants and animals.

Be sure to choose a high-quality DE product that is labeled “food grade” and thus safe to use in your garden. Also, while DE is generally safe for humans and animals when used as directed, it’s always a good idea to wear gloves and a dust mask when handling DE to avoid inhaling any fine particles.

Gear Used When Handling Diatomaceous Earth
Here’s the gear I use when handling DE on windy days.

This is especially important if you’re going to use a small powder duster to apply the DE to your plants or soil.

The first time I did so, I wasn’t wearing any protective eyewear. When I used the powder duster, the wind blew the DE back in my direction. I ended up closing my eyes and running away from that spot.

Simply put, wear protective glasses whenever you apply DE. Gloves are handy too since DE will cover your hands in flour if you use your bare hands.

More Information

If you’re interested in learning more about ways to keep your soil healthy and your plants happy, you might be interested in these articles:

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