BIOLOGICAL AND CHEMICAL PROPERTIES OF "VERMIWASH", NATURAL PLANT GROWTH SUPPLEMENT FOR TEA, COCONUT AND HORTICULTURAL CROPS

Abstract

Earthworms have been well exploited in agriculture worldwide inmaximizing crop production for many years. Amongst vermin-technology(Vermitech) practices, Vermiwash (Vw) has shown its field efficacy withmany crops. Vw is the wash of earthworm's celomic fluid and calcareouslayer and the watery extract of the bedding materials, which is known tocontain ample amounts of soluble macro and micronutrients, natural growthhormones, beneficial microbes, vitamins and amino acids etc. andnematicidal properties. However, the attributes to beneficial agronomicvalues of Vw have not yet been scientifically validated fully although thispractice is extensively being expanded in India and Sri Lanka. Therefore, thepresent study investigated the biological and chemical properties of elevensources of Vw resulted from different earthworm species and raw materials indifferent farms in Sri Lanka. Vw was tested as a source for hydroponics forlettuce in comparison with the Albert solution. The efficacy of regular foliarand soil applications of Vw on bush bean (Variety: Top crop), tomato(Variety: Thilina), nursery tea (cultivar: TRI 4071) and coconut (Variety:DxT) was also evaluated in comparison with vermicompost and conventionalchemical inputs in a series of bioassays.

The results of analyses revealed varying levels of biological and chemicalproperties of the test samples but within the optimal range for plant growth.Vw exhibited significantly lower levels of N, P, K but was rich in Ca, Mg,Zn, Fe and Mn; pH and CEC were also in the required ranges. Vwsignificantly (p=0.05) influenced the soil microbial biomass althoughindividual microorganisms were not identified; microbial biomass of Vw andcontrol were estimated as 4.95 and 3.20 x 10-3 mg C02/day/25g soilrespectively. Vw proved as a better alternate source to Albert solution forlettuce growth under hydroponic culture. The root length, root and shootbiomass and total leaf area of bush bean were significantly (p=0.05) affectedby Vw application compared to that of vermin-compost and synthetic fertilizer treatments. In nursery tea, Vw application lead to comparativelygreater callusing of tea cuttings but the increase in root formation and shootgrowth was not significant. Vw application boosted growth of coconutseedlings. However, no positive responses were seen with tomato.

The data suggested the potential exploitation of Vw in home gardening,indoor and container planting, biodynamic and organic farming etc. as afarmer friendly, culturally sensitive and economically viable natural product.Further work on attributes to plant growth such as determination of growthhormones, different doses and mass production of uniform quality Vw usingdifferent earthworm species and raw materials etc. would strengthen itssustainable use as an alternative growth supplement