Vermicompost, or biohumus, vermiculture, is a product of manure or organic waste processing by earthworms. It contains macro- and microelements, plant growth regulators (auxin, gibberellin), enzymes (phosphatase, catalase), has biological activity.
In the process of vermicompost formation the number of pathogenic microorganisms (salmonellae) and viruses decreases. Worms feed on all organic matter, which is 20-25% cellulose, such as straw, cardboard, paper, sawdust. Vermiculture abroad is regarded as an element of environmentally friendly agricultural production and is supported by the state in the form of preferential financing and exemption of vermiculture farms from a number of taxes.
- Mineral fertilizers
- Microfertilizers
- Complex fertilizers
- Organic fertilizers
The vermiculture method contributes to solving the problems of accumulation and processing of livestock waste:
- composting of liquid manure (Germany, Italy);
- recycling of household and industrial waste for fertilizer, e.g., municipal garbage, sewage sludge (USA, Italy, Netherlands);
- industrial waste recycling for compost (Japan);
- fat waste recycling (France, Toulouse).
Vermiculture uses the dung worm Euseniasoetieda, the so-called red hybrid Californian worm, bred in the late 1940s in the USA. It is distinguished by its great growth rate, fecundity, and longevity.
In its digestive tract organic remains undergo profound changes: they are decomposed into simple compounds, enriched with calcium, magnesium, nitrates, phosphorus; humic acids are formed; many mineral compounds are transformed into forms accessible to plants. Under the influence of calcite excreted in the esophagus, acids contained in the substrate are neutralized. The organic residues and earth that have passed through the worms’ intestines are discharged in the form of excrements, which constitute vermicompost (biohumus). During a day an adult worm passes through its intestines an amount of food equal to its own body weight. About 40% of this amount is consumed and 60% is excreted as coprolites. Biohumus is characterized by a high water-holding capacity and forms the components of the soil that determine its structure.
Red Californian worm processes almost all kinds of organic waste: manure, poultry manure, waste from fruit and vegetable depots, processing and pulp and paper mills, brewery waste, meat processing plant waste, sewage treatment plant sludge, household garbage.
Table. Chemical composition of biohumus, % (Sheugen et al., 2004)
| Humus | Magnesium | ||
| Nitrogen | Iron | ||
| Phosphorus | Copper | ||
| Potassium | Manganese | ||
| Calcium | Zinc |
To obtain high-quality compost, the substrate must undergo a fermentation process, which increases the temperature, resulting in the death of weed seeds and pathogenic microflora.
Regulatory requirements for the composition of vermicompost (biohumus) have been developed in various countries of the world. Worm excrement in biohumus should be at least 70% of the dry matter. There are no significant differences in requirements to the composition of biohumus both in Russia and in other countries.
Table. Requirements for the composition of biohumus[1]Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
| Content of organic matter, % | ||||
| C/N Ratio | ||||
| Available nitrogen content, % | ||||
| Contents P2O5, % | ||||
| Contents K2O, % | ||||
| Humus, % | ||||
| Moisture, % | ||||
| рН |
Vermicompost due to its high content of nutrients, agronomically useful groups of microorganisms and biologically active substances has a positive effect on the growth and development of plants and soil biota. While 1 g of manure contains 150-350 million bacterial colonies, vermicompost contains 100-200 billion. Biogumus is characterized by neutral reaction of environment, pH is usually in the range of 6.8-7.2.
Average doses of vermicompost for application to the soil are 3-5 tons/ha.
The yield of grain crops in the first year after applying biohumus increases by 0,6-1,0 t/ha, potato tubers – by 5-6 t/ha. Biohumus can be used in vegetable growing in open and protected ground.
Biohumus surpasses composts in many respects, has better physical properties – higher water-holding capacity, contains more nutrients available for plants, especially nitrogen, which is explained by higher number of nitrogen-fixing bacteria in worm coprolites. Humic acids, the content of which ranges from 5,6 to 17,6 % of dry matter, add particular value to biohumus.
In foreign countries, biohumus is used mainly as a nutrient substrate for growing seedlings of vegetables and ornamental plants. Due to high production costs, application for field crops is limited.
There are several groups of plants according to responsiveness to biohumus:
- Vegetable crops, tubers, root crops are characterized by high responsiveness – yield increases are 35-40%;
- Cereal crops respond well – yield increase up to 25%;
- Leguminous crops reacts satisfactorily – increase in yield up to 15%;
- Oil-bearing crops react little.
Sources
Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.