Today we tackle a topic dear to those practicing organic farming: vermicomposting (or worm farming). Essentially, we are talking about breeding worms. This type of farming is important as it allows the production of organic fertilizer through the natural action of these little creatures, which Charles Darwin had already attributed fundamental importance to for organic soil fertilization. The biological conversion of organic material into humus is a crucial process.
Let’s take a closer look at how worms can be raised for the production of organic fertilizer, both on a small scale, managing your home compost, and on a larger scale, for humus production even commercially.
The Worms
The worms, whose scientific name is Lombricus, are terrestrial annelids belonging to the family Lumbricidae.
There are hundreds of species of earthworms, but they can be grouped into three main classes:
- The anecic worms, which live deep in the soil within permanent burrows in the mineral layers of the soil. They emerge at night to drag the food (organic matter) deep into the ground.
- The endogeic worms. They also burrow the soil, but their burrows are generally at a lower depth. They feed on organic and mineral matter already present in the soil and rarely come to the surface.
- The epigeic worms, which live and move in the superficial litter of the soil. They do not have permanent burrows and feed on imported organic material decomposition.
It is these last worms that are used for vermicomposting. These small worms have the ability to process organic material provided to them quickly and efficiently.
The Red Worm
Eisenia fetida earthworms
The species of greatest interest for our discussion is called Eisenia Fetida, also known as the California red worm or simply the red worm.
It is the most common species used in vermicomposting.
The red worm is a small creature that can reach a maximum length of 7-8 cm. It has a diameter of 3 to 5 mm and weighs about one gram. It is very long-lived and can live up to 15 years.
Like all worms, it is hermaphroditic, meaning it has both male and female reproductive organs. Under optimal growth conditions, it reproduces approximately every 10 days. After fertilization, it lays small amber-colored capsule-shaped eggs, from which new worms hatch after about 20 days. These worms reach adulthood in just 3 months.
One of the notable characteristics of this species is its excellent resistance to both low and high temperatures. Red worms can comfortably handle a temperature range of 0 to 35 °C. In the winter, they slow down their activity, entering a sort of hibernation. However, continuous exposure to sunlight is not well tolerated. For this reason, they are rarely seen on the surface during the day; instead, they tend to seek shelter in the ground.
The Natural Role of Worms in Soil
If you have a soil rich in worms, you can consider yourself lucky. Their natural presence is a very positive indicator.
First of all, worms naturally fertilize the soil by facilitating the mineralization of organic matter, increasing nutrient dispersion, and promoting the reproduction of native populations of bacteria and microorganisms. In other words, they produce humus, the most fertile part of the soil.
Secondly, through their underground activity, they improve soil permeability and aeration.
Their natural presence indicates that there are no toxic substances in the soil, as they wouldn’t survive in such conditions. Red worms can naturally proliferate especially in soft and fresh soils, while they avoid compact and dry ones.
Unfortunately, not all soils naturally have a population of worms. For this reason, artificial intervention with vermicomposting is necessary. In a way, this practice reproduces the natural conditions of worm proliferation, thus producing humus, the quintessential organic fertilizer.
Vermicomposting can be implemented both on a domestic level, in a very artisanal way, and on a professional level to produce humus or worms for sale.
What Do Worms Eat?
Worms feed on organic matter, which they transform into humus through the gastric juices in their digestive system.
When we talk about organic matter, we mainly refer to organic waste, the kind of waste we normally use for home composting.
So, we’re talking about:
- Vegetable residues from the garden
- Properly shredded pruning waste
- Clean paper and cardboard
- Leaves
- Kitchen organic waste
These are all organic substances produced while living in the countryside and taking care of our garden.
However, the preferred food of worms is animal manure at a high degree of maturity. This is where the division occurs between vermicomposting using domestic and artisanal organic residues and the commercial production of humus.
In the latter case, animal manure is used for vermicomposting.
Domestic Vermicomposting
Many home garden enthusiasts practice composting. Well, with worms, you can simply improve and accelerate the compost production process.
It takes very little to get started. For example, you can set up a double box, where one box contains organic waste, and the other contains soil with worms, which you can purchase online from authorized producers.
The key is to feed the worms periodically, about three or four times a month. To do this, simply cover their bedding with a layer of organic matter.
However, pay attention to this step; the organic matter must be in an advanced stage of decomposition. It is therefore not possible to use the surface layer of the compost, but rather the more mature part. To collect it, simply turn the compost periodically, as usual, and use the more degraded part.
Another tip is to moisten the plant-based organic matter before feeding it to the worms. As you know, these little creatures prefer a moist environment.
Compared to regular composting, there are two main advantages. Firstly, there will be fewer unpleasant odors since worms work on the matter, making it odorless. Secondly, there will be faster degradation. This is especially true considering that worms consume daily a quantity of organic matter equal to twice their weight. This way, you get a completely natural organic fertilizer to use for your home garden. For completeness of information, note that it is not possible to sell humus produced from domestic vegetable scraps.
Professional Vermicomposting
When deciding to start a small company for the production of worm humus, you must refer to the regulations of the Italian Ministry of Agriculture, which regulate the production and marketing of fertilizers. In this case, we refer to Legislative Decree 29 April 2010, No. 75.
The regulations state that worm humus is produced exclusively using “manure from non-industrial farms and not using organic waste…”. These manures come from pigs, cattle, horses, and sheep.
The producer must also be registered in a special register of fertilizer manufacturers. The result of the production must follow a meticulous process of checks.
To understand how this activity works on a professional level, we contacted a company active in the sector, asking for explanations. It is a zootechnical company that has decided to accompany vermicomposting alongside its usual activities.
Starting a Professional Vermicomposting Activity
Worm farming plots
To start a vermicomposting business, you can use specific plots of mature manure, exclusively from company farms. Mature manure refers to organic matter that has already passed the thermophilic and mesophilic phase and has stabilized.
The plots serve as the habitat for worm growth. They have variable lengths and widths measuring 2 to 2.5 meters.
Depending on the season and needs, the plot is periodically irrigated. Additionally, organic matter is added every 15 days as food for the red worms.
To obtain worm humus, several months and a lot of patience are required. After all, it is a natural process that takes time.
Worm humus
Once the worm humus is collected, it is dried, sifted, and analyzed. Finally, it is packed in special bags of various sizes.
This humus looks very similar to normal soil. It is brown in color and very soft to the touch.
It is sold as organic fertilizer and is ideal for any type of organic fertilization in organic farming.
The contacted company has sent us a sample of its finished product, which we will test during the spring and summer. We will plant some pots with aromatic and medicinal plants: rosemary, basil, parsley, and sage, and perhaps some pepper plants too. We will try to provide a detailed report (maybe a comparison with other types of natural fertilizers) and see the real benefits that worms will bring to the crops we will examine. This way, you can decide whether to choose worm humus as an organic fertilizer for your organic crops or use other methods of natural fertilization.
Further Reading
- Rodale Institute – Vermicomposting for Beginners – Rodale Institute: A beginner’s guide explaining the process and benefits of using worms to compost organic waste, including the importance of managing organic residuals and the biology of earthworms.
