earthworms, segmented animals which have an important role in improving soil conditions for plant growth. Their burrowing improves soil mixing and aeration, and their feeding breaks down and redistributes organic matter, facilitating nutrient uptake by the vine. Because a high level of mixing of organic matter is associated with soil fertility, an abundance of earthworms is generally considered beneficial by many growers, especially those involved in organic viticulture. Earthworms are encouraged by mulches, which reduce soil surface temperature, provide organic matter, and help retain moisture. They are discouraged by bare, herbicide-treated soils and their species diversity and biomass are reduced by cultivation and by copper-containing fungicides. See also soil biota.
