Earthworm "tea" is simply the liquid which exudes or leaches out of a medium in which a large number of earthworms have been active. Earthworm tea has been shown to have a dramatic impact on plant health when applied to the surrounding soil. This improved plant health is a result of the tea significantly improving soil microbial activity - across many species - and possibly enhancing the development of mycorrhizae. This in turn enables plants to access trace elements and nutrients from the soil much more effectively. It also improves soil moisture retention and reduces compaction. Overall, the tea promotes a healthier "living" soil.
A couple of years ago Hamilton Russell Vineyards started working with a local farmer with an interest in producing this tea, to obtain amounts which would be significant for our 52 hectares of vineyards planted on extremely clay-rich and iron-rich soils. These shallow, less vigorous soils are prone to compaction, and while the quality and aesthetic benefits to our wines are clear, the soils are challenging to farm. A combination of carefully selected year-round cover crops, no use of herbicides and the application of earthworm tea has had a highly beneficial impact.
Organic cow manure is obtained in the area and forms a significant part of the medium in which the earthworms live. The "leachate" is channeled into underground tanks and then moved to storage tanks where it is aerated to keep it active. When enough has been gathered for a vineyard application, we collect it with our tractors and tanks and apply it immediately. A furrow is created along either side of the vines which the earthworm tea is dribbled into. The furrow is then closed over. This ensures that the tea does not "die" on or very near to the surface.
Ultimately we hope to see the benefit in our wines. Greater purity and more precision. We hope you begin to see the benefits in our 2015's and 2016's!