Research in our laboratory has shown clearly that some form of agitation or aeration during production of vermicompost ‘teas’ is necessary, if the ‘teas’ are to be effective in promoting crop growth and suppressing pests and diseases. We have research under way into the ‘shelf-life’ of vermicompost ‘teas’ under different temperatures and in a range of containers. We have demonstrated the transport of microbial activity and diversity, key nutrients, and enzymatic activity from solid vermicomposts into ‘teas’. Additionally, all our experience of the use of ‘teas’ in greenhouse trials has confirmed that the sooner a vermicompost ‘tea’ is used after it is ‘brewed’, the more effective it is in influencing plant growth and in suppressing pests and diseases. We have tested vermicompost ‘teas’ extracted from vermicomposts, that were produced from a range of animal manures such as pig or cattle wastes, as well as paper and food wastes, and all have been effective in promoting plant growth and disease suppression, independent of nutrient supply. After many laboratory and greenhouse trials, we decided that the optimal quantities of solid vermicomposts to water ratios were: 1:5 (20%), 1:10 (10%) and 1:20 (5%).

We have demonstrated clearly that solid vermicomposts can suppress plant parasitic nematodes in the field (Arancon et al, 2003). Our experiments on the effects of vermicompost ‘teas’ on nematodes were in the laboratory and greenhouse, in soils that had been artificially infested with the root knot of nematode (Meloidogyne incognita), which is a very serious pest of a wide range of crops all over the world. Six-week-old tomato seedlings were transplanted into 10 cm diameter pots containing a sand:loam (1:3) soil mixture to which the test ‘tea’ treatments were applied. Drench treatments of ‘teas’ were applied at seedling transplanting, and every two weeks thereafter. One week after transplanting 10,000 Meloidogyne hapla eggs were added to each plant pot in suspension in tap water. The eggs were collected from cultures maintained on infested tomato plants. Each treatment was replicated four times. Pots into which tomato plants had been transplanted were arranged on benches in a completely randomized design and the greenhouse was maintained at 25˚ C. Plants were watered regularly with tempered line water. Thirty days after infestation with nematodes, soil was removed from the pots and the roots were washed to assess the extent of root damage and the numbers of root knots. The washed roots were rated for numbers of root knot galls and the numbers of galls per unit wet weight of roots counted. The effects of the nematodes on plant height were determined by growth measurements, including heights, leaf areas, fresh and the dry weights of leaves from plant tops and the dry weights of all above-ground tissues at the end of the experiment.