Utilization of Earthworm Castings as Organic Fertilizer
Since the 1950s, crop fertilization has primarily relied on chemical fertilizers. The advent of chemical fertilizers caused a significant increase in crop yields and played a crucial role in addressing food shortages. However, the side effects of chemical fertilizers have become increasingly evident: melons are not fragrant, fruits are not sweet, vegetables lack flavor, and the production of chemical fertilizers requires large investments, high costs, and expensive prices. In particular, long-term use of chemical fertilizers severely damages soil structure, leading to serious soil compaction today. Experts call for extensive earthworm farming to reduce chemical fertilizer usage, fundamentally improve soil quality, and ensure sustainable agricultural development.
With the growing expansion of pesticide-free agriculture and the green food market, organic fertilizers have become an irreplaceable component for pesticide-free agriculture and green food production. Earthworm castings, as a highly effective organic fertilizer, uniquely combine organic matter, microorganisms, and growth factors to improve the soil environment, ultimately achieving goals such as increasing fertility, disease resistance, and soil nourishment. It is reported that earthworm castings are uniform in particle size, odorless, sanitary, and possess water retention and breathability three times higher than general soil. They contain 18 types of amino acids, 42.2% organic matter, and beneficial bacteria ranging from 200,000 to 200 million per gram.
The characteristics of earthworm castings as fertilizer and their application results include improving soil quality and reducing chemical fertilizer usage. Soil organic matter is a necessary condition for maintaining good soil physical properties and is also an important source of plant nutrition. The content of soil organic matter is an important indicator of soil fertility. Earthworm castings contain about 40% organic matter, which undergoes two fermentations and two animal digestions, making the resulting organic matter easily absorbable by plants.
It is reported that this type of earthworm casting organic fertilizer promotes the formation of soil aggregates, improves soil permeability, water retention, and fertilization capacity, benefiting microbial reproduction and proliferation. This enhances the soil's ability to absorb and store nutrients. After digestion by earthworms, the organic matter particles become much finer, with surface area increased over 100 times compared to before digestion, providing more opportunities for soil to contact air, fundamentally solving soil compaction issues. It also enhances crops' disease resistance capabilities. Agricultural experts point out that due to the long-term use of chemical fertilizers and excessive pesticides, the organic matter and microorganism content in the soil decreases annually, leading to an increase in soil-borne diseases in crops. Earthworm castings contain a large number of microorganisms, including at least two types of antagonistic microorganisms. When these beneficial microorganisms enter the soil, they can quickly suppress harmful bacterial reproduction, allowing beneficial bacteria to expand and reduce the occurrence of soil-borne diseases, making crops less prone to illness. Earthworm castings improve crop quality and restore natural flavors. "Earthworm casting organic fertilizer possesses the features of biofertilizer, bio-organic fertilizer, organic fertilizer, amino acid fertilizer, humic acid fertilizer, bacterial fertilizer, and micro-fertilizer, but it is not a simple combination of these fertilizers; rather, it is the most suitable combination for plant growth formed through the evolution of earthworms over millions of years." Field experiments conducted in some areas of China on large fields and economic crops show that earthworm castings significantly enhance crop quality, reasonably increase protein, amino acids, vitamins, sugar content, and restore the natural flavor of crops.
Earthworm farming has a small investment and quick returns, with abundant raw materials. Urban waste contains a large amount of organic matter such as fruit peels, vegetable leaves, and roots; rural livestock farms produce large amounts of manure; and there are plenty of crop straws and wild grasses left in farmland—these are all excellent feed for earthworms. Relevant personnel calculated that 1 billion earthworms can consume 400 tons of food in one day. Given that 10,000 tons of garbage contain 5,000 tons of organic matter edible by earthworms, 1 billion earthworms would consume it all within 100 days, producing approximately 4,000 tons of earthworm castings, worth up to 40 million yuan if sold at 1,000 yuan per ton. Especially in rural areas, everywhere can be a place for earthworm growth and reproduction, including dry land, paddy fields, orchards, vegetable gardens, front and backyards, roadsides, and ditches. As long as there is soil and plants, earthworms can exist. As long as pesticides and chemical fertilizers are not excessively used, water immersion does not last long, and no artificial killing occurs, earthworms will not die off naturally and will forever loosen and fertilize the soil for you. Therefore, enlightened individuals urge people to protect earthworms like protecting frogs, allowing them to reproduce in large numbers and benefit humanity. Earthworms have great potential in agriculture. Their continuous underground activity makes the soil loose and soft, allowing more water and air to penetrate the soil, benefiting crop growth. Earthworms consume large amounts of decaying organic matter and soil daily, excreting feces. Earthworm castings are an odorless, non-toxic, clean, pollution-free, efficient, and high-quality fertilizer rich in nitrogen, phosphorus, and potassium. Not only do they improve soil quality, but they also make melons more fragrant, fruits sweeter, and vegetables fresher. A farmer named Wang Dayuan from Xingguo County, Jiangxi Province, once raised ducks in his vegetable field using earthworms, resulting in higher vegetable yields and better quality in the sections where earthworms were raised.
As research deepens and practical experience increases, earthworm farming will undoubtedly bring about a new green revolution in agriculture. Sewage sludge is a regular byproduct of wastewater treatment plants, and its handling has always been an important issue faced by municipal management. Currently, there is no mature technology domestically to handle sludge, mainly relying on random discharge or landfilling. Since sludge contains toxic and harmful substances, this may cause secondary pollution, potentially entering the food chain and harming public health. Experts both domestically and internationally responsible for the research topic have explained that sewage sludge contains a large amount of organic matter as well as nitrogen, phosphorus, and potassium, making it a good fertilizer. However, due to the presence of harmful substances, it limits its resource utilization. Using earthworms to process sewage sludge is more effective and thorough than traditional methods. While earthworms consume harmful substances in the sludge, they secrete substances beneficial to plant growth. Thus, sludge processed by earthworms becomes an excellent organic fertilizer, realizing the resource utilization of sludge.
1. Physical Properties
Earthworm castings are a black, uniform, fine-grained material with a natural earthy smell, having good porosity, aeration, drainage, and high water retention. The tiny granular structure helps promote maximum soil-air contact when mixed with soil, preventing soil compaction and hardness. Due to their large surface area, many beneficial microorganisms can survive in earthworm castings, along with the ability to absorb and retain nutrients.
2. Chemical Properties
Many organic wastes, especially livestock manure, are generally alkaline, while most plants prefer a slightly acidic growing medium (pH: 6-6.5). During the worm digestion process, the pH of the waste decreases, becoming neutral.
3. Biological Properties
Earthworm castings are rich in bacteria, actinomycetes, and fungi. These microorganisms not only mineralize complex substances into plant-available effective substances but also synthesize a series of biologically active substances such as sugars, amino acids, and vitamins, giving worm castings many unique properties.
Reasonable Application of Vermicompost:
1. Can be used as a base fertilizer or top dressing for grains, vegetables, fruit trees, melons, and landscaping greenery.
2. Combining with long-lasting chemical fertilizers shows even more significant effects.
3. Absolutely safe for crops, it can directly contact seeds or seedlings without causing any harm.
Precautions:
1. Best not to apply on the soil surface to avoid direct sunlight affecting microbial activity and nutrient volatilization.
2. Store in a cool, dry place, avoiding rodent infestation.
Product Features:
Earthworm castings are a black, uniform, finely textured substance with a natural earthy fragrance, possessing excellent persistent fertility, aeration, drainage, and water retention. The nutrients are comprehensive, making it the ideal fertilizer for various flowers. It has the unique feature of never burning roots when used alone.
1. Earthworm castings are rich in easily absorbable nutrients, with ample and long-lasting fertility.
Earthworm castings contain not only elements like nitrogen, phosphorus, and zinc but also trace elements such as iron, manganese, zinc, copper, magnesium, and 18 types of amino acids. Organic matter and humus content can reach around 30%.
2. Earthworm castings contain a large number of beneficial microorganisms and amino acids.
Each gram of earthworm castings contains about 100 million beneficial microbial colonies, and more importantly, they contain antagonistic microorganisms and unknown plant growth hormones.
3. The only natural aggregate and adsorptive structural fertilizer.
Earthworm castings are the best hydrophilic and adsorptive flower fertilizer. Used flower soil will not compact, and the fertilization and moisture retention effects are excellent. The unique porous structure effectively absorbs indoor formaldehyde, benzene, and volatile organic compounds.
Microbial Mechanism of Action in Earthworm Castings:
Through the life activities of beneficial microorganisms and earthworms, plant hormones such as auxins, cytokinins, gibberellins, and indole acetic acid are produced, promoting plant growth and regulating plant metabolism. Large amounts of polysaccharides are also generated, combining with plant secretions and mineral colloids, organic colloids, forming aggregates that enhance water retention capability. Beneficial microorganisms within also produce antibiotics with strong antagonistic activity and broad antibacterial spectra, restricting the growth of pathogenic bacteria and inhibiting soil-borne diseases in plants.
Mechanism of Adsorption of Harmful Gases by Earthworm Castings:
Earthworm castings themselves are a black, uniform, naturally earthy-smelling substance with a loose, porous aggregate structure. They possess excellent aeration, drainage, and high water-holding capacity. Due to their large surface area and colloid network characteristics, many beneficial microorganisms can survive. This unique physical structure and colloid property gives it a miraculous adsorption effect.
Usage Methods:
1. In flower pots, mix earthworm castings at a ratio of 1:3 (one part earthworm castings to three parts garden soil), eliminating the need for additional fertilization for 1-2 years or soil replacement, or add 1-2 cups (about 2 liang) of earthworm castings every 2-3 months as a mixed nutrient soil, usually using a ratio of one part earthworm castings to three parts soil.
2. When used as top dressing, apply directly to the plant roots and water thoroughly.
3. When repotting plants, shake off the original soil, remove old and withered roots, then surround or directly plant the root system with earthworm castings, filling the gaps between the roots and watering thoroughly.
4. Spread 1-2 centimeters of earthworm castings on the top layer of flower soil to fully exert its fertilizing effect, keeping the earthworm castings moist while also effectively absorbing indoor formaldehyde, benzene, and volatile organic compounds.
Main Nutrients:
Total N+P+K ≥ 5%, Beneficial live bacteria ≥ 0.2 billion/g, Organic matter ≥ 30%, Humic acid ≥ 20%, Neutral pH.
(Responsible Editor: Jin Di Agriculture)