Many vineyards have low soil organic matter
and fertility. Soils like these may be more difficult to manage and require higher inputs
of fertiliser, water and other soil amendments to sustain adequate vine growth and yield.
The application of mulch and compost to under-vines has many potential benefits.
The type of mulch used in vineyards is usually determined by the cost, availability of products
and also what is trying to be achieved Mulch is a layer of material spread on the
soil surface. Some of the more common materials used for mulch in vineyards include straw,
cover crop slashing�s and grape marc. Other inert types of mulch include rocks and plastic.
In vineyards, the most important benefits gained from using mulch include reduction
of evaporative loss of soil moisture from the soil surface, the protection of the soil
surface extreme temperature fluctuations and weed suppression.
Compost is an organic product that has been stabalised by biological and chemical decomposition.
Mature compost is stable and resistant to further decay. Essential elements of the composting
process include controlled aeration, moisture and temperature for optimal microbiological
decomposition and effective pasteurization of organic materials.
The Australian standard for compost specifies maturity and stability, and ensures that a
manufacturers claims can be supported. For example, manufactures of certified compost
provide information about their products including the suppression of weed seed germination and
pathogens, and its nutritional analysis. A specification sheet showing a typical analysis
should be supplied with all compost products as the composition of each product will vary
depending on its source. This allows growers to best address requirements of the vineyard
and make informed decisions about the type of compost to purchase and apply.
The most important difference between mulch and compost is that mulch has not decomposed
to any extent when it is applied. Mulch is not compost but compost can be mulch.
The advantages of using mulch in vineyards include: water savings, weed suppression,
improved water infiltration, increased soil biota and decreased solar radiation and reflection.
Some mulches, depending on their source may also have nutritional benefits
Compost has a number of additional benefits: Mature compost is usually pH neutral and contains
medium to high levels of Phosphorus, Potassium, Magnesium and Calcium. Compost allows the
slow release of nitrogen which extends the period of nitrogen availability and may also
reduce nitrogen loss caused by leaching. Compost provides a good source of bacterial
and micro flora and stimulates earthworm activity which assists soil nutrient cycling and may
also increase vine resistance to disease. The organic matter provided by compost improves
physical soil characteristics and its water and nutritional holding capacity. The layer of soil protection provided by both
mulch and compost has the additional benefit of reduced reliance on herbicides.
Some disadvantages of mulch that should be considered include: The provision of a haven
for pests including earwigs, rodents or snails, Increased frost incidence in some regions,
increased fire risk, some mulches may impede vineyard operations for example very thick
spread straw mulch can impede mechanical harvesting. Straw mulch can also be very slippery so vineyard
workers should use caution. The cost of mulch and compost is highly variable.
The cost depends on the product, availability and transport. It is also important to consider
the potential cost of special equipment for the application of mulch.
The use of compost and mulch in vineyards has many benefits but also presents some disadvantages
in particular situations. Always weigh up the risks and benefits before applying compost
or mulch. Additional resources to assist your decision
making can be accessed at the following websites.