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Ideally, farmers would use organic fertilizers instead of chemical fertilizers because chemical fertilizers might burn the plants, transfer harmful bacteria, and dry the soils. In contrast, pesticide-free fertilizers help with root development, micronutrients, and seed germination.

However, gardeners might still feel unsure about choosing natural fertilizers since picking one organic manure over another is not always easy. For example, how do you know which one is the most advantageous, worm castings or bat guano? Both are enriching and offer a range of benefits, but which one is the most beneficial for soil?

After unbiased research, we found that worm castings might be better than guano. The article will show you a side-by-side comparison to put the debate to rest once and for all.

Our Pick From Organic Fertilizers

We prefer worm castings over bat guano because of their nutrient value and because they are one of the cheapest manures to get. In addition, worm castings are readily available at local and online shops, and they are easy to use on-site. Bat guano is not only expensive, but it is hard to find naturally. Bats live in caves, and it is impossible to harvest their manure for everyday farmers.

Another benefit of worm castings is their accessibility, and they are easy to add to the compost pile and maintain in the garden without doing any hard-lifting. Unlike guano, worm castings are easier to keep under control.

Another issue is the eating habits of bats. One cannot always control the dietary habits of bats, but you can control what you feed the worms. As you know, animal excretion depends on what they eat. For example, chicken manure compost contains more nitrogen because of the high nitrogen content in their diet. That is one of the primary reasons we choose worm castings over bat guano any day. 

About Worm Castings

When earthworms eat and produce waste in the soil, they contribute to the ecosystem. Thus, worm castings are organic waste that acts as an organic fertilizer for the compost. In essence, earthworm castings are the manure of earthworms and worm poop deep within the soil.

In fairness, worm castings are not a fertilizer but rather a soil conditioner. They improve the soil’s quality to help plants absorb the nutrients and are a vital supplement for any compost pile. At the same time, they are not stand-alone fertilizers. If you want a healthy garden, you will need to use other manures rich in nitrogen.


Worm castings are rich in hummus and nitrogen, crucial for soil growth. In addition, the hummus prevents plant diseases while neutralizing the soil’s environment. It is also water-soluble and easy for plants to absorb.

Unlike chemical fertilizers, worm manure will not harm the soil’s microbiology. Unlike pesticides, they will not burn plants nor contaminate the soil. Worm castings are highly concentrated with beneficial microbes, whereas chemical fertilizers and pesticides contain synthetic nutrients.

Earthworm castings naturally have much-needed nutrients for healthy plant growth. According to aMississippi Agricultural and Forestry Experiment Station study, worm poop can improve seed germination.


  • Easy to apply in the form of worm manure tea
  • Odor-free
  • A better alternative to chemical fertilizers
  • Promote soil aeration


  • Time-consuming
  • It is not a stand-alone fertilizer

About Bat Guano

Bat guano is the organic waste of bats and a mixture of solid feces and liquid manure. It may also contain the decayed materials of fruit, animal remains, and cave minerals. Thus, the quality of this fertilizer depends on the nature of the cave rock formation, the bat species, and its dietary habits. In addition, bat droppings undergo a complex mineralization process, and these transformations make bat guano one of the best manure options on earth.


Bat guano tea is rich in phosphorus, making it practical for root development. It also delivers beneficial microbes during the flowering stage of the plant. Bat manure also helps break down dense nutrients in the soil so that the plants can absorb them faster.

Nutrients stay longer in the compost pile, long enough for the plants to mix with the compost, promoting soil hydration. When the water remains longer in the soil, plants cannot get enough through their roots to avoid leaf burn.

Bat droppings have different types such as:

  • Peruvian seabird guano
  • Indonesian bat guano
  • Jamaican Bat Guano

Each comes with different NPK values for distinctive compost uses. It also comes in several colors; however, the colors usually do not determine the quality of this manure.


  • Rich with minerals
  • Good source of carbon, nitrogen, and potassium
  • Enhance the flavor of plants
  • A rich mix of organic materials


  • It may contain fine dust that is harmful to human lungs
  • Environmentally-harmful harvesting
  • Non-renewable resource

Similarities Between Worm Castings and Bat Guano


Both worm castings and bat manures can come in organic tea form, making them easy to mix in garden containers. Fertilizer tea is also more accessible for the plants to absorb and stay longer in the plant roots.


Castings and guano are feces of living animals. Both originate from a mix of chemical reactions in the animal’s stomach. They react to the natural habitat and then mix with the surrounding environment. These processes can take a long time and enrich the mixed manure’s quality.

Soil Conditioner

They are soil conditioners that help the plants get more nutrients, nitrogen, and potassium from the soil. Farmers can also spray the tea from both manures to speed up composting, and they are a practical top dressing for the compost.

Differences Between Worm Castings and Bat Guano

Natural fertilizer

Bat guano might be more potent as an organic fertilizer, but worm castings act more as a supplement. Yet, it would help if you used other manure types to enhance the effects and get the best results. For example, some farmers may add chicken manure to the compost pile to get enhanced plants.


Worms are more abundant in nature, and they are easy to raise, but bats are cave-dwelling creatures. Compared to potassium-rich bat guano, worm manure is much cheaper to manufacture.


Usually, worm castings are more nitrogen-rich than bat guano, and the latter contains more phosphorus, potassium than nitrogen. As mentioned earlier, it depends on what you feed the animal. In other words, you can feed worms a phosphorus-rich diet if you want more phosphorus for your plants. Bats eat fruits and insects by nature, and it is near impossible to herd bats and force a specific diet on them.


Are worm castings better than bat guano when it comes to organic nutrients? Bat guano contains enough goodness for garden soil. However, worm castings are more accessible when mixing your composting pile. You are more in control of mixing the composting pile, which means you control the output, budget, and quantity. They are eco-friendly and in our opinion the best for fertilizing your garden.

Grow Bigger Plants with Simple Grow

Do you wish your plants would grow bigger? Was your garden less than it should've been last year?

If you're tired of growing puny vegetables and fruits, it's time for an upgrade...Simple Grow Worm Castings!

What are worm castings? Another term for worm manure. Why would you want to use it in your garden, raised beds, and house plants? Because it makes them grow bigger, faster and healthier...with no chemicals!

How do worm castings do this? It's like giving your plants a powerful multivitamin with everything they need to grow. Trace minerals, nutrients, and most importantly...worm castings are chock full of beneficial microbes. Why does that make a difference?

In recent years, we've learned the importance of gut bacteria for humans and know that it impacts so many different parts of our health. The same thing applies with worms. Gut bacteria from the worm's digestive tract gets into the soil from the worm castings and promotes plant health. Plants have a symbiotic relationship with the microbes from the worm's digestive tract. Plants respond to it and grow really big...really fast!

If you've never tried worm castings before, you owe it to yourself to give them a try. Instead of using traditional chemical fertilizers from the big box store, why not try fresh, certified organic worm castings this year? You'll be able to grow bigger, healthier plants that you actually can feel good about eating. 

Take advantage of our special bundle sale on 25lb bags today!


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