You’ve heard all the buzz about vermicompost, or “worm poop”. The organic substance decomposed by worms is soft like humus and is often used as a type of compost in organic gardens.
How good is vermicompost as a fertilizer when compared to the other fertilizer types?
Vermicompost is the best fertilizer compared to synthetic NPK fertilizers and other types of organic compost. It has at least 3 times more the amount of vital plant nutrients in readily available forms that are slowly released over time. It is also rich in plant growth hormones, soil enzymes, and a diverse microbial population for soil regeneration. And it is natural, renewable, and does not pollute the environment.
In this article, we are going to compare the benefits of worm castings with chemical fertilizers, conventional compost, and cow manure to find out the power of the little red wigglers.
1. Does vermicompost have NPK?
Vermicompost is an excellent natural fertilizer for plants as it contains rich nutrients for plant growth.
It contains high amounts of nitrogen (N), phosphorous (P), potassium (K), micronutrients, beneficial soil microbes and also plant growth hormones, and enzymes.
The exact amount depends on the variety of organic materials that are fed to the worms. The commonly available nutrients in vermicompost, according to a study by Sinha et al. (2009), are:
|Nitrogen||2 – 3%|
|Potassium||1.85 – 2.25%|
|Phosphorous||1.55 – 2.25%|
|Calcium and Magnesium||22.67-47.6 meg/100g|
(Sinha et al., 2009)
2. Vermicompost vs. chemical fertilizer
Chemical fertilizers are inorganic substances produced synthetically in the factory. There are many types of chemical fertilizers, for example, urea, ammonium sulphate, ammonium phosphate, and ammonium nitrate. But they are commonly known as “NPK fertilizers” with different proportions among the three major macronutrients (Nitrogen, Phosphorous, and Potassium).
2.1 Better yield and crop quality
The application of vermicompost produces higher quality and quantity of plants, fruits, and crops compared to the use of chemical fertilizers.
For wheat the production increases by at least 35%; Flowers are more colorful and bigger in size; And fruits and vegetables have better taste and texture and have a longer shelf life (Ganeshnauth, Jaikishun & Homenauth, 2018).
2.2 Slow nutrient release
The nutrients in the worm castings are released slowly into the soil for plant absorption over a period of time.
As earthworms feed on decaying organic matter, the organic substances move through the alimentary canal of worms and are broken down into mineral forms that are readily available for immediate absorption by plant roots. A thin layer of oil is also deposited on the worm castings. This keeps the nutrients available for over 2 months before the oil erodes.
In contrast, chemical fertilizers release their nutrients quickly in soil, resulting in quick depletion of soil nutrients due to leaching underground by rainfall and oxidation under sunlight.
A study shows that with an application of 100kg urea fertilizer in farm soil, only 20 to 25% is available to plants because 40 to 50% gets oxidized and escapes as “ammonia” (NH3), and another 20 to 25% leaches underground polluting the groundwater (Suhane 2007).
2.3 Contains plant growth hormones and enzymes
Vermicompost contains enzymes such as amylase, lipase, cellulose, chitinase, which serve to break down the organic matter in the soil to make them become available for uptake by plant roots.
It also contains growth-promoting hormones “auxins”, “cytokinins”, and flowering hormone “gibberellins”.
2.4 Resistance against diseases and pests
Plants that are grown with vermicompost are found to have higher resistance against pests and diseases.
For example, organic farmers in India have seen a reduction of pest attacks by at least 75% with their cauliflowers and banana after the application of vermicompost.
Interestingly, the number of termite attacks has reduced in the soil where there is a high worm population (Ganeshnauth, Jaikishun & Homenauth, 2018).
In another study, root disease is also found to have reduced from 98% to 26% in Capsicum and 82% to 18% in tomato in soils with compost, compared with soil with chemical fertilizers (Ayres, 2007).
2.5 More beneficial soil microbes
Soil that is amended with vermicompost is more fertile and self-sufficient. This is because when organic substances pass through the bodies of earthworms, a diverse population of microbes is introduced to the worm castings.
The microbial activities continue to produce weak acids that can dissolve rock minerals and organic matter in the soil into readily available forms, resulting in less reliance on external sources of fertilizers. This is important for soil regeneration.
2.6 Higher water retention capacity
Worm castings have excellent porosity, meaning that it has a high surface area similar to that of peat and can hold up to 9 times their weight in water.
It is fluffy and is never compacted, which is perfect for plant roots that require a growing medium with good drainage.
Since the soil has a higher water retention capacity, seeds germinate and seedlings grow faster and plants do not need to be watered as much and as often. It also provides a higher surface area for absorbing and retaining nutrients.
2.7 Does not pollute the environment
Worm castings are natural and renewable because they recycle organic waste into fertilizers that are useful to plants.
On the other hand, chemical fertilizers are harmful to the environment at all stages, from the procurement of the petroleum raw material to the production process in factories where energy is used and pollutants are generated.
Also, the use of chemical fertilizers in farms can alter soil chemistry by disturbing the mineral balance in the soil. The minerals from the chemical fertilizers are also quickly released and easily leached, polluting rivers and underground water.
3. Vermicompost vs. conventional compost
Vermicompost is also a better fertilizer compared to conventional compost which is basically organic waste decomposed naturally without the help of worms.
- In terms of the time of decomposition, vermicomposting requires only 4 weeks or half the composting time of conventional compost to finish and can be used immediately without curing.
On the other hand, conventional composting requires 8 weeks for the organic substances to break down plus another 4 weeks of curing before it can be used safely with plants.
- Vermicomposting contains a much larger and more diverse population of microbes dominated by Mesophilic bacteria which thrive at a moderate temperature of 68 – 113 Fahrenheit (20 – 45 Celcius).
In contrast, conventional compost has a much smaller microbial population mostly consisting of Thermophilic bacteria which grow best at a high temperature of 106 – 252 Fahrenheit (41 – 122 Celcius).
- In terms of the nutrient content, studies have shown that conventional compost has a higher amount of ammonium whereas vermicompost has a higher amount of nitrates, which is the more available form of nitrogen (Atiyeh et al., 2000).
Worm castings also have a higher proportion of other vital minerals, such as phosphorus (P), potassium (K), sulfur (S) and magnesium (Mg), and plant growth hormones, than conventional compost.
4. Vermicompost vs cow manure
When compared to animal manure such as cow manure, vermicompost is also better as it contains at least 3 to 4 times more macronutrients than cow dung compost.
|Nutrient||Vermicompost||Cow manure compost|
Also, vermicompost is more porous and water retentive than cattle dung compost, reducing the need for irrigation by 30-40%.
5. How to use vermicompost as fertilizer?
Mix a handful of vermicompost into the soil or put it in the bottom of a planting hole, so that it is covered and near the roots.
If it is left on the surface uncovered, vermicompost will dry out and lose the moisture required by microorganisms and microbes to inhabit.
6. How much vermicompost should I use as fertilizer?
For potted plants, mix vermicompost into the soil at a ratio of 10 to 20%. Anything more than that will not yield more benefits. For plants in the garden, put a handful of vermicompost into the planting hole.
7. How long is vermicompost good for?
Worm castings can keep for up to a year when stored in a dark, cool place.
Sunlight will result in a loss of moisture and nutrient content. The moisture content should be kept at a 40% level.
If it dries out, sprinkling water over it can keep it moist.
When stored properly, the worm castings can be kept for a long time because of a thin coating of oil. The oil coating is produced by the worms and functions to preserve the nutrients so that they can be slowly released into the soil over a period of time.
Vermicompost is hands down the best fertilizer for plants for both the home garden and farm production.
When compared to chemical fertilizers, vermicompost contains more nutrients and mineral forms that are readily available over a long period of time without nutrient loss to the environment by leaching. It also contains plant enzymes, hormones, and a rich and diverse microbial population that can help protect against pests and diseases and help with soil regeneration.
When compared to other types of organic compost such as cow manure, vermicompost is also better in terms of a shorter amount of composting time and 3 to 4 times higher number of macronutrients.
Agarwal, Sunita, 1999. Study of Vermicomposting of Domestic Waste and the Effects of Vermicompost on Growth of Some Vegetable Crops. Ph. D Thesis Awarded by University of Rajasthan, Jaipur, India. (Supervisor: Rajiv K. Sinha)
Atiyeh, R.M., Dominguez, J. Sobler, S & Edwards, C. A. (2000). Changes in biochemical properties of cow manure during processing by earthworms (Eisenia andrei) and the effects on seedling growth; Pedobiologia, 44: 709-724.
Ayres, M. (2007). Supression of Soil-Borne Plant Diseases Using Compost; Paper Presented at 3rd National Compost Research and Development Forum; Organized by COMPOST Australia, Murdoch University, Perth.
Ganeshnauth, V., Jaikishun, S., & Homenauth, A. A. a. (2018). The Effect of Vermicompost and Other Fertilizers on the Growth and Productivity of Pepper Plants in Guyana. In (Ed.), Automation in Agriculture – Securing Food Supplies for Future Generations. IntechOpen.
Sinha, R., Herat, S., Valani, D. & Chauhan, K. (2009). Earthworms Vermicompost: A Powerful Crop Nutrient over the Conventional Compost & Protective Soil Conditioner against the Destructive Chemical Fertilizers for Food Safety and Security. American-Eurasian Journal of Agricultural & Environmental Sciences, 5 (S): 01-55
Suhane, R.K. (2007). Vermicompost (In Hindi); Pub. Of Rajendra Agriculture University, Pusa, Bihar; pp: 88 (www.kvksmp.org)
TNAU Agritech Portal. (n.d.). Organic Farming: Compost.