The 2009 ASHS Annual Conference

Compost tea is an extract prepared by steeping and brewing compost in water. While the total amount of nitrogen and other nutrients is generally small, compost teas are often reported to stimulate plant growth and prevent diseases. Proposed mechanisms for these benefits include the effects of microorganisms or plant growth regulators that might be present in the tea. Analysis of compost tea derived from worm castings (vermicompost tea) revealed high populations of a diverse array of bacterial species. In addition, radioimmunoassay (RIA) of the phytohormones present in the vermicompost tea provided evidence that the concentration of the isopentenyladenosine was sufficient to promote a plant growth response at the rates that compost tea is typically applied. The vermicompost tea is being analyzed further to quantify the important bacterial groups and concentrations of other hormones (auxins, gibberellins and abscisic acid) that might be present in the tea. Data from ongoing whole plant experiments will be presented.

Key words: Compost tea, Radio immune analysis (RIA), Phytohormones, Vermiculture, Vermicompost.