Role of vermicompost in organic based integrated farming system

K Nandini Devi, Y Bebila Chanu and Y Sanatombi Devi
Vermicomposting is the term given to the process of conversion of biodegradable matter by earthworms into vermicast which are rich in NKP (nitrates, phosphates and potash), micro nutrients and beneficial soil microbes. In the process, the nutrients contained in the organic matter are partly converted to more bio-available forms. It plays a vital role in organic based integrated farming system for eco-friendly environment in the 2nd Green Revolution.
Vermicomposting as a means for agricultural waste management
Globally, 140 billion metric tons of biomass is generated every year from agriculture. Biomass takes in the form of residual stalks, straw, leaves, roots, husk of seed shells, bagasse and animal husbandry waste. Widely available, renewable virtually free waste biomass is one important resource. With the global campaign to combat climate change, countries are now looking for alternative sources of energy to minimize greenhouse gas (GHG) emissions. Aside from being carbon neutral, the use of biomass for energy reduces dependency on the consumption of fossil fuel, hence, contributing to energy security and climate change mitigation.
As a common practice, direct combustion of agricultural residue results in air pollution thereby posing risk to human and ecological health. Biomass is a renewable resource that causes problems when not used. The challenge, therefore, is to convert biomass as a resource for energy and other productive uses. Its use is carbon neutral, can displace fossil fuels and helps reduce GHG emissions while closing the carbon cycle loop. Therefore, utilization of agricul- tural waste in any environmentally friendly way is very important. Agricultural wastes can be converted into organic manure (vermi-compost) with the help of earthworm. Some of the suitable earthworm species for vermicomposting in India are Eiseniafaetidaana Eudri-luseugeniae.
Vermicompost as a means for nutrient management:
Organic farming and organic products are gaining momentum in the agricultural sector. It s main objective is to maintain healthy soil that produces healthy plants and create a balance between the interconnected system of health of people, soil, soil microorganism, plants and animals. One of the requisite of organic farming is the use of organic fertilizers that can be produced by farmers themselves using locally available plant materials. The increasing popularity of the use of compost, organic fertilizer also evolved from the recognition that most of our agricultural lands are nutrient-degraded and soil deterioration keeps on advancing. Soil fertility deterioration is a major constraint for higher crop production in many parts of our country. The increasing land use intensity without adequate and balanced use of chemical fertilizers and with little or no use of organic fertilizers as compost have caused severe soil fertility deterioration resulting in poor harvest of crop grown. Since fertile soil is the fundamental resource for higher crop production, its maintenance is a pre-requisite for long term sustai- nable crop productivity. Soil organic matter of soil is declining with time due to intensive cropping and use of higher doses of nitrogenous fertilizers with little or no addition of organic fertilizers.
An organic fertilizer does more than providing organic nutrients it improves the physical properties (infiltration rate, water holding capacity and bulk density), chemical properties (Cation Exchange Capacity, fertility, etc.) and increases bio- logical activity (respiration rate). Castings can hold 2-3 times more water than their weight in soil. The slow release nature of organic nutrients probably prevents leaching losses of same magnitude as from the inorganic fertilizers. Among beneficial soil microbes sti-mulated by earth worms are “nitrogen-fixing & phosphate solubilizing bacteria”, the “actinomycetes” & “mycorrhizal fungi”. Studies found that the total bacterial count was more than 10/gm of vermicom-post.
Vermicompost as a means of plant protection
Vermicompost has an ability to fight soil-borne plant diseases such as root rot. There are other agronomic benefits of composts application, such as high levels of soil-borne disease suppression and removal of soil salinity. One study reported that mean root disease was reduced from 82% to 18% in tomato and from 98% to 26% in capsicum in soils amended with compost. Nematodes and diseases will not ruin gardens or plants if the soil is rich enough for them to grow fast. Studies reported statistically significant decrease in arthropods (aphids, buds, mealy bug, and spider mite) popu-lations, and subsequent reduction in plant damage, in tomato, pepper, and cabbage trials with 20% and 40% vermicompost additions. Munroe doing co- mmercial vermicompos-ting in California, US, claims that his product repels many different insect pests. His explanation is that this is due to production of enzymes “chitinase” by worms which breaks down the chitin in the insect’s exoskeleton. As regards the effects of vermicompost on insect pests and mites, field studies have shown that the addition of vermicompost to soil significantly reduces the incidence of the psyllids Hetero psyllacubana, Apro-aeremamodicella, jassids, aphids, beetles and spider mites. Studies also reported considerable suppression of root knot nematode and drastic suppression of spotted spider mites and aphid in tomato plants after application of vermicompost teas (vermiwash liquid).
Vermicompost as plant growth regulating activity
Some studies speculated that the growth responses of plants from vermicompost appeared more like “hormone induced activity” associated with the high levels of nutrients, humic acids and humates in vermicom-post. Researches show that vermicompost use further stimulates plant growth even when plants are already receiving “optimal nutrition”. It consistently improved seed germination, enhanced seedling growth and development, and increased plant productivity significantly much more than would be possible from the mere conversion of mineral nutrients into plant available forms. Some studies have also reported that vermicompost contain growth promoting hormone “auxins”, “cytokinins” and flowering hormone “gibbe-rellins” secreted by earth- worms. Positive effects of vermicompost include sti-mulated seed germination in several plant species such as green gram, tomato plants, petunia and pine trees. Vermicompost also has a positive effect on vegetative growth, stimulating shoot and root development. The effects include alterations in seedling morphology such as increased leaf area and root branching and also has been shown to stimulate plant flowering, increasing the number and biomass of the flowers produced as well as increasing fruit yield. Vermicompost contains antibiotics and actinomycetes that help in increasing the “power of biological resistance” among the crop plants against pest and diseases.
The writers are froim College of Agriculture, CAU, Imphal
CAU, Imphal. Email: prmmcell@gmail.com