Sunday, 6 June 2010

Battling Weeds with Fungi and Woodchip

Weeds are one of the biggest challenges for an organic vineyard. Without the use of herbicides weeds can quickly take over and compete with the vines, which is especially bad news for new vines trying to get established.

Agricultural soils which have been ploughed for many years often end up being dominated by bacteria rather than fungi. There is a correlation between plants and their preference for soils that are dominated by bacteria versus those that are fungal dominated or neutral. Since the path from bacterial to fungal domination in soils follows the general course of plant succession (see earlier blog on the Soil Food Web), it is possible to predict what type of soil particular plants prefer. In general, perennials, trees, and shrubs prefer fungal dominated soils, while grasses and weeds prefer soils dominated by bacteria. Vines generally do best in soils that have an F:B (fungal/bacteria) ratio of between 2:1 and 5:1.

At the moment the vineyard is heavily dominated by bacteria which means that weeds will quickly dominate if nothing is done to control them. Longer term the fungal content of the land will naturally increase and we will try and help this process by using compost teas with a high fungal content. In the short term however we are just about winning the battle by using huge amounts of woodchip as a mulch and have just finished spreading over 1000 m3 of the stuff on the 12,600 newly planted vines.