Down to earth

By TheHindu on 18 Apr 2017 | read

These wriggling, weak-looking worms hardly trigger respect on sight. But looks can be deceiving, and these down-to-earth worms could actually hold the key to reinstating soil vitality. That is because earthworms eat huge volumes of leaf and all kinds of organic litter (as much as three to five times their body weight, every single day) and cast out nutrients that are easily absorbed by plants. In fact, vermicompost (organic wastes composted by earthworms and associated organisms is considered to be the most nutritious of all manures), while vermiwash (water run through columns of organic matter and cow dung composted by earthworm and microbial activity) has been found to promote plant growth, thanks to the presence of the plant growth hormone IAA in vermiwash. Earthworms also secrete a slimy fluid that contains nitrogen, a plant nutrient. And in the process of burrowing, earthworms mix up the top soil with the bottom soil which distributes manure and moisture throughout the soil. The burrowing action also aerates the soil, which is crucial for plants’ growth.

In conversation with us is Dr. Sultan Ismail, international expert on earthworms. This Chennai-based soil biologist, ecologist and founder of Ecoscience Research Foundation is the one who first coined the term vermitech, the technology for composting organic wastes using earthworms. "Earthworms are the pulse of the soil. The more earthworms there are in the soil, the healthier is the soil," says Dr. Ismail. Here is how we can welcome earthworms into our gardens and potted plants. For more, check out

What earthworms can we introduce in our garden or potted plants?

Local worms are recommended rather than imported worms because local worms burrow better and are more adapted to survive in our soil. I recommend Perionyx excavatus (surface dwellers) and Lampito mauritii (subsurface burrowers). A mix of surface and subsurface worms is ideal.

Where can we obtain earthworms?

You can collect earthworms from your neighbourhood. One can also contact the local agricultural department, municipalities, and nurseries of the forest departments, and select horticulture shops for earthworms. Alternatively, you can use cow dung sold in cow sheds. This cow dung will have eggs of local worms. Acquire this cow dung in a semi-dry condition, neither as fresh cow dung nor as dry cakes.

How can the soil be readied to sustain earthworms?

Keep mulching the soil. Don’t clear away the fallen leaf litter. This mulch layer is crucial and will protect the soil’s moisture and beneficial microbes and attract earthworms. Keep the soil moist but not waterlogged. For this, sprinkling of water once a day will do. Native trees attract worms, so plant native trees rather than exotic species. Remove construction debris from the soil. And don’t spray synthetic pesticides. This kills earth worms.

What is the food that has to be supplied for these earthworms in the soil?

Besides naturally falling leaf litter, you could add semi-composted kitchen waste to the soil occasionally and mix it with the soil lightly. Soon worms will multiply and arrive at an ideal sustainable number.

Can earthworms spread any disease?

Earthworms do not cause any plant disease. They don’t spread any plant infection, unless the infection is already present in the vicinity. And they are absolutely harmless to human beings. In fact, earthworms are used in Siddha medicine.

Can we introduce earthworms to soil in pots?

Yes, but keep watch and remove a few worms, in case they become too numerous for the soil and loosen the soil. Dead earthworms needn’t be removed. They decompose fast and become part of the soil.

Will earthworms crawl into our houses from soil in potted plants/gardens?

Earthworms prefer to stay close to soil with food source and moisture.

Earthworm trivia

Earthworms can grow back segments or parts of their body that get severed!

Common earthworms are just a few centimetres long, but the the Giant Gippsland Earthworm found in Australia reaches a length of 4 metres.

Earthworms are hermaphrodites, have both sex organs within the same individual.

So fascinating are earthworms that the grand old man of evolution, Sir Charles Darwin studied earthworms for over 44 years and put up his observations in his book ‘The Formation of Vegetable Mould Through the Action of Worms, with Observations on Their Habits’, which instantly became a best seller.