The same problems are encountered in the making of “compost tea”, which is similar to liquid compost, except that the water used to make the product has an oxygen content sufficient to support the growth of microorganisms. A compost teais typically made by supplying a kit which includes a “tea” bag containing compost, with the addition of other chemicals, and brewing the “tea” in liquid, in the presence of oxygen, for an extended period of time. The resulting compost tea may be used as a fertilizer, or as a composition for preventing plant diseases.