Mulching is the process of covering the ground surface or berm (soil strip directly below the vine row) with any dead plant material such as vine cuttings, grape skins, straw and even rooibos tea. This process is used to control weed growth and to limit water loss through evaporation. Furthermore it lowers the ground temperature and limits erosion. Brush cutters cut down the cover crops in the row and sprinkle the finely chopped material as mulch on the berm.
The most popular mulch used is straw. Due to the cost factors, it is often only used on the berm or other weak growing spots in the vineyard. In the Swartland where wine farming is often combined with grain farming and straw is readily available, it is sometimes also used in the vine rows. Wine farmers move away from using sawdust as mulch as it can lower the soil pH. Mulch can later on be incorporated into the soil in order to increase the organic content.
It also increases the microbiological content of the soil by slowly rotating and increasing the amount of saprophytic fungi - these microorganisms feed on dead organic material and helps with the breakdown of organic matter. It also affects insect and arthropod populations and studies have found that a smaller amount of pests are present in vineyards with mulch.By Marinda Louw