Vermicompost in solid and liquid forms as a plant-growth promoter

Vermicompost, derived from animal manures and plant wastes, was used in pot-trials to determine the effects of various commercial formulations on plant growth. Radishes grown in varying concentrations of vermicompost, in a mixture with sand ranging from 0 % to 100 %, showed significant differences in germination and development to maturity. Germination was reduced from 95 % to less than 50 % with increasing vermicompost concentrations. Harvest weights were proportional to the rates of addition of vermicompost, with the yield of plants in 100 % vermicompost up to ten times greater than in 10 % vermicompost. The vermicompost continued to promote plant growth following pasteurization, but when the vermicompost was sterilized, growth of radishes was little better than in the sand control without vermicompost. 'Super' vermicompost, 'biologically-enhanced' with proprietary blends of bacteria and enzymes, did not improve the effects on radish growth compared with the 'Regular' vermicompost. A vermi-liquid, leached from vermicompost in active worm-beds, inhibited the early growth of radishes when applied at seeding. Subsequent weekly applications of the diluted liquid improved plant growth, and significant increases of up to 20 % in radish yields were recorded. It was obvious that higher concentrations of vermicompost promoted increased plant growth, but did not provide a suitable medium for seed germination. A single application of vermi-liquid had no effect on germination but reduced seedling growth; repeated doses were needed to significantly increase the weight of radishes at harvest. Caution should be exercised in promoting these preparations as 'fertiliser substitutes'.