RESEARCH ARTICLES CURRENT SCIENCE, VOL. 98, NO. 9, 10 MAY 2010 1202 *For correspondence. (e-mail: mgcpcri@yahoo.co.in) Coconut leaf vermiwash: a bio-liquid from coconut leaf vermicompost for improving the crop production capacities of soil Murali Gopal 1, *, Alka Gupta 1 , C. Palaniswami 2 , R. Dhanapal 1 and George V. Thomas 1 1 Central Plantation Crops Research Institute, Kudlu P.O., Kasaragod 671 124, India 2 Present Address: Sugarcane Breeding Institute, Coimbatore 641 007, India Coconut leaf vermiwash (CLV) was produced from actively vermicomposting coconut leaf litter + cow dung substrate (10 : 1 w/w basis) by Eudrilus sp. It significantly increased the seedling vigour index of cowpea and paddy at 1 : 10 and 1 : 15 dilutions in laboratory trials. Field trials carried out in red sandy loam soil (Arenic Paleustults) resulted an increase of 36% fresh biomass weight of cowpea with application of CLV at 1 : 10 dilution. In maize, increase in cob yield by 5–10% and in bhendi (okra) 22–33% increase in fruit yield were recorded at 1 : 5 dilutions of CLV. A concomitant increase in populations of general and plant beneficial microorganisms and soil enzyme ac- tivities in the rhizosphere of CLV-applied plants were also recorded. Soil organic carbon content increased in the CLV-applied plots in all the crops studied, but the total N, available P and K content in soil varied in different crops. The study indicated that CLV must be used in graded doses. Its application increased the crop production capacities of soil by (i) enhancing the organic carbon contents in the soil and (ii) increasing the populations of the soil microorganisms, particu- larly plant beneficial ones, and their activities which would have facilitated increased uptake of the nutrients by the plants resulting in higher growth and yield. Keywords: Bio-liquid, coconut leaf vermiwash, soil enzymes, soil microflora, soil nutrients, vermicompost. CONVERSION of agricultural, urban and industrial refuse into vermicompost by employing specific earthworms is quickly becoming a favoured method of recycling wastes in many countries 1,2 . Wastes from plantation crops like coconut 3 , arecanut and cocoa 4 , coffee 5 and acacia 6 , which contain high percentage of lignin and phenols, have also been successfully converted to vermicompost using dif- ferent species of epigeic earthworms. Application of vermicompost rejuvenates the depleted soil fertility, enriches the available pool of nutrients, maintains soil quality and conserves more water and biological resour- ces 7,8 . The vermicomposting technology can also be util- ized for generating a bio-liquid termed as vermin wash or vermiwash 9 . Vermiwash is a liquid leachate collected by allowing excess water to saturate the actively vermicom- posting substrate in such a way that the water washes the nutrients from the vermicast excreted by the earthworms feeding on the substrate as well as the earthworm’s body surface. This bio-liquid is rich in nutrients and plant growth hormones 9 and its application has been reported to stimulate anthurium 10 , increase soil nutrient status and yield of paddy 11 and biological productivity of mari- gold 12 . Similarly, vermicompost leachate has also been reported to be suitable as formulation for liquid ferti- lizer 13 and other agricultural uses 14 . Zaller 15 had reported that foliar applications of vermicompost leachate improved certain quality parameters of tomatoes besides suppress- ing Phytophthora disease. However, most of the studies mentioned here report the beneficial effects of vermiwash or vermicompost leachate produced from animal manure + earthworms or from the earthworms alone. In this article, we present the production of vermiwash from actively composting coconut leaf litter + cow dung substrate (10 : 1 w/w basis) by Eudrilus sp., its chemical, biochemical and microbiological properties, and its potential as a bio-liquid to increase crop growth and yield accompanied with soil, microbial, enzyme and nutrient properties. Materials and methods Coconut leaf vermiwash production Vermiwash production can be done basically by two methods. One method involves soaking soil + cow dung + earthworms substrate in excess water in plastic tub and siphoning the wash periodically from the bottom of the tub 9 whereas the other involves releasing the earth- worms in lukewarm water and agitating them gently so as to shock them to secrete higher amount of body fluids and mucus 16 , which actually is the true vermin wash. For production of coconut leaf vermiwash (CLV), we developed a batch method that was minor modification of