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How do I use a worm farm to improve my soil?



Worm farming, also known as vermiculture is the method used to produce worm castings. Worm castings are a nutrient-rich, organic material produced by worms as they digest organic matter. These castings are rich in beneficial microorganisms, plant growth hormones, and essential nutrients that can promote plant growth and improve soil health. The aim of setting up a worm farm is to harvest the castings in a way that does not disturb the worms. There are many different designs that allow the castings to be harvested in a way that minimises the disturbance but before looking at designs let’s understand why we should go to the effort of setting up a worm farm.



Why are worms so important for soil?


It is a common misconception that worms eat organic matter breaking it down in their digestive gut. In fact, worms grind the organic matter down to extract the microbial juices after which they spit out the compressed material. This process speeds up the decomposition of that material by increasing surface area and allowing more microbial activity to take place. Worms use sand as grit to allow them to grind the material and extract the microbial nutrition which they rely upon. The material that makes it into the digestive tract of the worm is further digested by the worm’s gut microbiome. The gut of the worm is packed with highly beneficial soil microbes which make up the bulk of the worm casting. These microbes include bacteria, fungi, and protozoa, which all play a critical role in further breaking down the remaining organic matter that the worm spat back out. The microbes go to work in the soil and begin releasing essential nutrients for plants as they perform the functions of the soil food web.


Worm castings also contain plant growth hormones which signal plants produce to trigger a biological function. For example, the plant hormones cytokinins and auxins are found in worm castings. These hormones are responsible for regulating cell growth, promoting cell division and cell elongations. Cell elongations allow plants to direct their leaves towards the sun as it moves across the sky to capture the most light possible. These hormones are vital for plants in the growth phase of their lives. For these reasons worm castings are regarded as one of the best soil amendments available, so how do you make worm castings?


What do you need to produce high-quality worm castings?


To produce the best quality worm castings, worms need to be kept in conditions that mimic their natural environment. Creating a worm farm is similar to building a 5-star hotel, your worm clientele is very picky and they need you to care for their every need. If they do not like the conditions you have given them they will abandon the worm farm by crawling out and most likely dying outside of the farm. Luckily once you know what conditions they like you’ll easily be able to maintain your worm farm. Worms naturally live in a cool, moist and well-drained environment that is rich in organic matter. Worms cannot tolerate sunlight so worm farms are always sheltered from direct light, by covering it we protect against bird predators too. When filling the worm farm we first add bedding material which is a safe space for the worms as it is won’t create any heat. Items such as newspaper, egg boxes, aged compost or shredded leaves are perfect choices for bedding material.



Building your worm farm.




Building a worm farm can be done in many different ways, picking the best design for you often relies on matching the space you have available to a specific design. From small indoor bins to bathtub-sized worm farms, there are many designs for gardeners to choose from. The basic goals for a worm always remain the same so creating a design that meets those goals and fits into your space is recommended. So what do your worms want from their worm farm?


  • A container which allows for good drainage. There must be a drainage plug at the lowest point of the container which allows the leachate to drain out. Another misconception about worm farming is that the liquid that drains out the farm is some sort of ‘Worm tea’ this is false. What drips out of the worm farm is known as leachate because the liquid passively flowed through the material creating a dark-coloured liquid. This leachate has not passed through the gut of the worm and often is mistaken as a microbial inoculation when in fact it will most likely contain anaerobic microbes. Having the container tilted towards the drainage hole helps to prevent liquid pooling and stagnating at the bottom of the container.


  • Sealed off with a lid. Worms need to be protected from the elements and bird predators. Having a lid to close is important as long as there are ways for air to enter passively. It is important to allow enough oxygen to be present so that we don’t promote anaerobic organisms. Drilling holes in the side of the container is recommended.


  • The bedding material. As mentioned good bedding material is the safe space for the worms, this is first added before any feeding takes place. Once you have your bedding in you can add your worms. For a beginner, I always recommend starting with red wriggler as they are the most ‘user-friendly’ type. If you are considering using a different variety remember they may have different environmental preferences compared to what is described here.


  • Feeding. The worms will process fresh organic material rapidly. The higher the worm population the more rapidly the worms will be able to deal with that material. They are able to self-regulate their populations based on the quantity of food that enters the system. The more frequently you feed the more worms your farm can support. It is a double-edged sword as overfeeding your worms is the most common error people face. Overfeeding kitchen scraps starts to create adverse conditions for the worms and often promotes flies. Feed slowly and combine the feeds with more bedding material if issues start to show.


  • Moisture. Worms prefer damp and cool conditions. By placing the worm farm out of the sunlight we prevent drying out from occurring. Even so at times, you will find that the worm farms dry out and water must be added. A moisture range of 65% - 75% is ideal for your worms. If you flood your container the worms will not tolerate that for long either dying out or leaving the container.


  • Harvesting. Design a method to separate the worms from the castings. Some designs open at the bottom to allow the harvesting of material that has been processed already. Others are stacked box systems which allow the person to rotate the bottom and top boxes, this allows you to encourage the worms to move between boxes based on where you feed. These are usually small-scale systems but make for very easy harvesting. The main aim of harvesting is separating worms and castings in a way to protects your precious worms and keeps them on the farm.



Creating a design that works for you can take some research but by following these 6 goals your design will work well for the worms. Start with a small system first and build from there. Find some video ideas here. Buying worms can be quite expensive so by starting small you can increase your worm’s population first. This allows you to split your worms between the new and old worm farms which means your populations will continue to rise as the worms have more space.


What is the best way to use my Worm Castings?




Once you have harvested your precious castings what do you do with them? The castings can then be used as a top dressing for plants, or they can be made into a compost extract by mixing them with water to be drenched into your soil. This allows the beneficial microbes to begin working in your soil. Worm castings are a highly sought-after soil amendment and can be beneficial to your plants in a number of ways. They improve soil structure, and water-holding capacity, and provide a slow release of nutrients. They also promote healthy microbial populations in the soil, which are essential for nutrient cycling and pest management.


To learn more about worm farming and how to manage a worm farm, I recommend checking out my E-Book, "A Guide to Living Soil and Composting" written by Wesley Soule. In the book, I cover composting, worm farming, and soil science along with a range of other regenerative farming practices. Additionally, my business SoilScopes offers soil testing services that can test the quality of your worm castings, compost or soil by assessing the microbial balance and biomass.


Partnering with nature means you can harness the benefits of natural systems to improve soil and crop growth. Starting with small steps like building a worm farm to convert your organic waste into a soil-building amendment is the beginning of closing the loop. By working towards closed-loop living we can grow our own food and recycle our organic waste back into the soil. If you want to learn more about partnering with nature, subscribe to our newsletter to receive our latest releases.


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