As fertilizer feeds the plant, Vermicomposting feeds the soil. It is a process in which the material to be decomposed passes through the worm's digestive tract and the product is the worm poop! It smells like recently turned soil. A single worm eats more than half of its weight daily and millions of worms process tons of waste daily.
Vermicompost Preparation Process:
Suitable Earthworm Species:
There are 5 most commonly used worm species in the compost making process:
• Red Wiggler or Tiger worm (Eisenia fetida), most efficient compost producer, nutrient release, and early decomposition are the characters of this worm. It reproduces very fast and is resistant to disturbance.
• European Night Crawlers (Eisenia hortensis)
• African Night Crawlers (Eudrilus eugeniae)
• Blue-worms (Perionyx excavates), commonly found in the tropics.
• Lumbricus rubellus is not very efficient for a shallow compost bin.
Red wiggler is one of the most popular earthworms used in commercial as well as small-scale Vermicompost manufacturing. (Suthar & Singh, 2008)
Digestion of Litter by Earthworms:
Earthworm's intestines produce several different enzymes, microorganisms, and hormones which aids in the rapid digestion of the material ingested by them. Rapid digestion means that the earthworm excretes out the half-digested material in the form of "casts" which are further acted upon by the microbes (earthworm gut associated microbes) transforming them into a mature product that is known as Vermicompost.
It is good because complete digestion will cause the absorption of all the nutrients and the end product would be useless. Earthworms can convert the food into Vermicompost within 4-8 weeks as compared with the traditional composting (use only microbes) that takes 10-20 weeks. (Pathma & Sakthivel, 2012)
Changes Taking Place In The Waste/Litter:
Earthworms have been noticed to bring a lot of changes in the substrate (upon any kind of waste they are feeding) including the electrical conductivity, pH, C: N ratio, and release many essential nutrients into it. Compared to the parent material:
• The Vermicompost would have reduced/less pH, which will make the product acidic.
• An increased amount of nitrogen, phosphorus, potassium, and other micronutrients.
• Conversion of parent material into humic acid (40-6- % more than present in the traditional compost), fulvic acid, and other organic acids. The Vermicompost when added to the soil will increase the nutrient uptake capability of plants, aeration of the soil, and supports the microbial activity.
• C: N ratio is an indicator of the degree of decomposition taking place. During the process, both CO2 and N are lost rapidly which shows the speed of the decomposition process. That is why the Vermicompost has a relatively less C: N ratio due to the intense decomposition taking place there. (Biruntha et al., 2020)
• Vermicomposting expedites the mineralization in the parent material. The mineralization process converts/decomposes the chemical compounds in the organic material into the less complex forms that can be easily taken by the plants.
Commercial/Large Scale Vermicomposting:
Commercial vermicomposting is widely practiced in the U.S, Italy, Malaysia, Canada, etc. which is later used for farming, export, or making compost tea. Cattle manure, agriculture waste, food and cotton processing mills waste, grass clippings, brewery waste, etc. are the products used as parents material in commercial vermicomposting. The Windrow method and Raised Beds method, are the two techniques associated with it.
In the windrow method, long lines of decomposing material are made to let it dry and windrow turners are used to turn the material from time to time. it is a cost-effective, and sustainable method for the farmers to manage agricultural as well as cattle waste efficiently.
In raised bed/flow-through system, the worms are fed with worm chow at top of the bed, and castings are collected at the bottom end. It is more suitable for indoor operations, especially in cooler climates. The other advantage is that you do not need to separate the worms as they constantly keep moving towards the fresh material.
Small Scale Vermicomposting:
Readymade bins (adaptive containers) are easily available for home vermicomposting. Red dwellers (who eat on the food waste/trash) and symbiotic associated microbes are the best combinations for food decomposition. The material that can be converted into Vermicompost at a small scale may be:
• Any fruit/vegetable/coffee filters/fruits and vegetable peels, etc.
• Leaves, pruned stems, and grass clippings.
• Newspapers, tea bags, toweling, eggshells, etc.
Bin composting is a very efficient technique to use the material that will otherwise become the pollution source. It has been reported that a family in the US produces 18 pounds of waste daily and an average American consumer creates almost 5 pounds of waste on daily basis. So why not to convert that waste into useful products without any physical effort and save the environment?
Harvesting Signs and Methods:
The ready-to-harvest compost would be of dark color, moist like a sponge, no or a few uneaten scraps of substrate left behind, etc. In a finished Vermicompost, microbes slow down the metabolizing activity or stop it completely and no visible changes are taking place in the end product.
Different harvesting methods are being practiced depending upon the kind of compost, saving of worms, time, and labor availability. (Lin & Yuan, 2021)
In this method, pyramids of Vermicompost are made in the afternoon, the worms will instinctively go down in the bottom of the pyramid, collect the compost from the above and continue to repeat until the mound is left behind with worms mostly. This is suitable for small-scale Vermicompost harvesting.
Nutrient-Status of Vermicompost:
• Organic Carbon: 9.5-17.98 %
• Total Nitrogen: 0.5-1.5 %
• Available Phosphorus: 0.1-0.3 %
• Potassium: 0.15 %
• Calcium: 22.7-70 mg/ 200 g
• Magnesium: 22.7-70 mg/ 200 g
• Sulphur: 128-158 ppm
• Copper:2-9.3 ppm
• Zinc: 5.7-11.7 ppm (Swati & Reddy, 2010)
Benefits of Vermicomposting:
Role in Soil Fertility:
The addition of Vermicompost improves soil structure, water, and cation holding capacity, nutrient status of soil, and aeration. The healthy soil would have fewer soil-borne diseases, soil erosion chances, leaching of nutrients, etc.
Vermicompost restores “Biological fertility” of the soil i.e. stimulates the population of beneficial microbes. The worm's mucus stimulates antagonism between various soil microbes, as a result, only the fittest are left behind. This activity produces hormone-like biochemical and antibiotics which fastens the plant's growth.
Role of Vermicompost in Plants Growth:
It has been studied that Earthworms produce plant growth promoters in Vermicompost, as a result, it significantly improves the productivity and growth of plants. Mineralization activity during the compost preparation has been converted the complex chemical compounds into forms that are easily taken up by the plants. So, now it contains nutrients such as phosphorus, calcium, nitrate, soluble potash, and magnesium in plant-available forms.
The addition of compost makes soil porous, which helps in deeper root encourage and reduce soil compact which in turn reduces cultural operation’s needs.
Role of Vermicompost in Disease Management:
A soil with low organic matter content will cause unhealthy root growth and the chances of disease attack on a frail plant will be more. Thermophilic compost has been reported to be effective against soil-borne disease suppression. It improves soil's nutritional and physical standards by microbial antagonism phenomenon. In this, soil's microbial population increases that struggles in rapid decomposition and make soil aerated which in turn improves plant's root growth and vigor (earthworm's feeding suppresses pathogens survival in the soil).
Benefits to Environment:
Vermicompost has reduced the metabolic gap through the continuous recycling of unwanted products. There is 56 % reduction of waste has been recorded due to its recycling and reuse from the past few years. The average life span of an earthworm is 5-7 years. It means that you can produce tons of organic fertilizers within a single investment.
Solid waste treatment in incinerators produces greenhouse gases while landfills, pollute the soil and underground water. During Vermicomposting, there is no such emission of methane, nitric oxide, etc., and beneficial conversion of waste at the production point (reduce waste transport need to landfills). (Singh & Singh, 2017)
Role in Nematode and Insect Pests Control:
Insects always attack the plant whenever they found it weak and weak soil produces weak plants. A soil deficient with basic micro and macronutrients or its physical properties is not suitable for plant growth, which would increase the chances of insect attack. Vermicompost contains phenolic acids that feed upon the insect pests and reduce and gradually eliminate them. The same action is performed by the addition of Vermicompost for the control of plant-parasitic nematodes. (Pathma & Sakthivel, 2012)
Earthworms are known as “nature’s plowman” and “Farmer’s Friend”. Vermicomposting is environment-friendly, cost-effective, and easy to carry out the process. It producing nutrient-rich compost on one side while on the other side, it is helping in reducing the amount of waste that is destructing our environment. Vermicompost is an excellent biofertilizer for amending unhealthy, unsuitable soils with minimum input/investment. At the same time, it is providing the farmer with the disease, insects, pathogens, and nematodes control in a natural way. This pollution controller mechanism has been efficiently practiced in many developed countries and controlling environmental/water/air pollution.
Biruntha, M., Karmegam, N., Archana, J., Selvi, B. K., Paul, J. A. J., Balamuralikrishnan, B., . . . Ravindran, B. (2020). Vermiconversion of biowastes with low-to-high C/N ratio into value added vermicompost. Bioresource technology, 297, 122398.
Lin, J., & Yuan, Q. (2021). A novel technology for separating live earthworm from vermicompost: Experiment, mechanism analysis, and simulation. Waste Management, 131, 50-60.
Pathma, J., & Sakthivel, N. (2012). Microbial diversity of vermicompost bacteria that exhibit useful agricultural traits and waste management potential. SpringerPlus, 1(1), 1-19.
Singh, A., & Singh, G. S. (2017). Vermicomposting: A sustainable tool for environmental equilibria. Environmental Quality Management, 27(1), 23-40.
Suthar, S., & Singh, S. (2008). Vermicomposting of domestic waste by using two epigeic earthworms (Perionyx excavatus and Perionyx sansibaricus). International Journal of Environmental Science & Technology, 5(1), 99-106.
Swati, P., & Reddy, M. V. (2010). Nutrient status of vermicompost of urban green waste processed by three earthworm species-Eisenia fetida, Eudrilus eugeniae, and Perionyx excavatus. Applied and Environmental Soil Science, 2010.