Does Fertilizer Kill Worms and Other Helpful Bugs and Insects

The humble worm brings many benefits to our gardens, especially when it comes to enriching the soil. Not only do they increase aeration and water infiltration, but they also add nutrients and can help to balance soil pH too.

In addition, worms can help to protect soil against harmful pests and diseases and promote healthy bacteria. With so many uses, the question to be asked is does fertilizer kill worms and other helpful garden bugs? 

The truth is, there are many fertilizer products that won’t harm or kill worms. Quite the opposite in fact as many contain ingredients that will support the presence of these organisms.

There are a few exceptional circumstances, however, so it is always worth understanding the impact that fertilizers can have on such beneficial wildlife. Keep reading to learn all about fertilizers and their effects on worms.

Can Worms Live in Fertilized Soils?

Worms survive pretty well in fertilized soils. For example, adding organic fertilizers like sewage wastes, animal manure, paper pulp, potato processing waste, or compost has a positive effect on earthworms. 

According to the United States Department of Agriculture, organic fertilizer supports earthworms and can double or triple their number. Similarly, applying inorganic fertilizers in the right quantities supports the presence of worms in the soil. 

That said, worms may struggle at first to survive in ammonia and ammonia-based fertilizers, although it is possible for their population to recover after a while.

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How Does Fertilizer Affect Earthworms?

The ingredient list for organic fertilizers can be up to 100% natural and includes animal and plant by-products such as blood meal, fish bone, seaweed, and humic acid. These are nutrient-dense sources of food for worms.

When added to the soil and used in conjunction with manure or compost, crop production is increased, resulting in an even more beneficial food source for worms.

The result is a thriving clew of worms, busily reproducing, whilst simultaneously enhancing the nutrients and condition within your soil.

Inorganic fertilizers, however, can have a negative impact on worm populations if soil pH levels are affected because of using them.

Worms thrive in soil with neutral pH levels, but many synthetic fertilizers contain ingredients such as sulfate and/or ammonia and these are known to increase soil acidity. The end result is a diminishing number of worms within your soil.

Do Worms Eat Fertilizer?

According to the NADC, worms eat decaying roots and leaves, nematodes, bacteria, and fungi found in soil, and decomposing animals. Since many organic fertilizers contain similar ingredients, it’s fair to assume that worms would consume this too.

Does Fertilizer Kill Worms?

Most fertilizers will not kill worms. Instead, fertilizers support and enhance worm populations by increasing the production of crops which are then consumed by worms.

Synthetic fertilizers that contain chemicals such as sulfate and ammonia are prone to increasing soil acidity and this is likely to affect worm numbers.

This is because worms prefer neutral pH levels, and are unable to tolerate acidic soil environments, causing populations to decrease.

Is Organic Fertilizer Safe for Worms?

It’s safe to say that worms can tolerate organic fertilizer. Better still, they are attracted to heaps of compost, mulch, and manure. 

The only problem with organic matter is the high temperatures emitted during composting which may make the worms uncomfortable. However, as soon as the compost cools, it’s an excellent environment for the worms. 

It’s important to note that you should only apply manure after aging it for several days. That’s because fresh manure is rich in nitrogen which may introduce unfavorable conditions for the worms.

Does Organic Fertilizer Attract Insects?

Without a doubt, an organic fertilizer will attract beneficial insects to your garden. These include bees, dragonflies, and ladybugs.

These bugs are beneficial as they feast on harmful pests such as aphids in your garden.

Are Organic Fertilizers Harmful to Pollinators?

It is unlikely that organic fertilizers cause any harm to pollinating insects. In fact, the increase in flora and fauna that results in the use of fertilizers is likely to enhance insect numbers and the potential for pollination.

However, beware of inorganic fertilizers that contain pesticides that are specifically designed to eliminate pests and bugs. These will certainly have a detrimental impact on our helpful pollinating population.

Fish Emulsion

The smell of fish emulsion may attract unwanted insects like flies and predatory animals, such as:

  • Foxes 
  • Cats 
  • Coyotes
  • Raccoons
  • Dogs 

These predators may dig up your farm in search of fish. Don’t be misled by the claim by some fish emulsion manufacturers that it has no odor. In my experience, there is always an odor. 

Blood and Bone Meal

Bone and blood meal fertilizers help to balance carbon in compost heaps and can be an excellent source of nitrogen for many a vegetable plot. However, as with the fish emulsion, the smell of meat will attract nearby pests such as possums and raccoons, which may invade your garden.

To avoid such problems, make sure you fully incorporate the bone or blood meal into the soil to minimize the odor.

Can Fertilizer Harm Beneficial Bugs and Insects?

When used correctly, most organic fertilizers are unlikely to cause damage to the beneficial insect population in your garden.

However, fertilizers that contain pesticides are designed to kill insects and their toxicity does not differentiate between beneficial critters and those that can wreak havoc in your garden.

The only way to avoid damaging our diminishing population of pollinators is to choose a fertilizer product that is free from pesticides and consider an alternative method of pest control instead.

Is Fertilizer Considered a Pesticide?

There is a distinct difference between fertilizers and pesticides, and both have a unique purpose.

Fertilizers are designed to add nutrients to the soil. These nutrients not only enrich the soil, but they are also absorbed by plants helping them to develop healthy roots, stems, and leaves as well as effectively carrying out their growth cycle.   

The purpose of pesticides is to prevent, eliminate, and control pests.

What Are the Effects of Ammonia and Ammonia Fertilizers on Earthworms?

When used regularly, ammonia-based fertilizers can increase acidity levels in soil pH to a level that cannot be tolerated by worms.

Worms prefer a neutral soil pH range between 5.0 to 8 and anything higher is likely to reduce their population. 

What Happens When You Add Lime to Soil?

If your soil is highly acidic, turning to lime can help. Lime lowers acidity, and because most earthworm species favor neutral pH levels, you can expect their population to increase significantly. 

In addition, the calcium in lime is beneficial to their growth. Lime also increases plant growth, resulting in more plant residues which is another indirect way to benefit earthworms too.

Final Thoughts Does Fertilizer Kill Worms

So does fertilizer kill bugs and worms? The answer is not always. Besides making the soil more fertile, fertilizers support worms and benefit bugs and insects by providing them with more food and better living conditions. Just ensure you apply them as per the recommendations and avoid harmful fertilizers.