The use of compost in the vineyard has many advantages including the uterlisation of vineyard
and other waste streams.
For example, many vineyards apply apply grape marc from the winery, manures from nearby
feedlots, or from garden waste collected by local councils.
The use of grape marc from winery in the vineyard closes the loop on waste.
Composted grape marc provides the benefits of compost including
A neutral pH, the slow release of nitrogen, medium to high levels of Phosphorus, Potassium,
Magnesium and Calcium and efficient nutrient utilization.
Soil moisture has increased retention
Beneficial soil bacteria, microflora and earthworm activity are enhanced and physical soil characteristics
improve.
Un-composted grape marc may also be used in the vineyard.
A partially combusted grape marc can be used as a high organic carbon soil conditioner
which contains trace elements.
If the marc has been through a steam distillation process it is weed free and does not germinate.
If you are considering using uncompacted grape marc in the vineyard, it is important to neaturalise
the pH and optimize the Carbon to Nitrogen ratio to facilitate nutrient availability.
This can be achieved by partial breakdown of the grape marc, but will be more complete
by undergoing the composting process.
Uncompacted grape marc is also often high in salts, especially Potassium, excess Potassium
is detrimental to soil and vine health and may also effect grape and wine composition.
High potassium concentration in vines can lead to high pH in the grapes.
Movement of Potassium into the berry causes the release of positive ions which increasing
berry pH.
High pH is associated with microbial spoilage of wine, colour instability and premature
aging of wine.
Acid additions will not shift pH sufficiently, this is due to a buffering action especially
with red wine as Potassium continues to leach from the skins.
There are two ways that potassium can accumulate in fruit.
Potassium accumulation can occur directly or indirectly.
Direct uptake occurs from the soil to the vines.
On the other hand, indirect accumulation can occur as a result of changes canopy conditions.
The leaves of a dense, shaded canopy will move more Potassium into berries compared
to an exposed canopy.
Export and accumulation of Potassium from shaded leaves might occur as a result of improved
soil conditions created by compost, which subsequently increases canopy density.
Trials conducted in NSW vineyards investigating the effect of high soil potassium and berry
potassium and pH have found a positive relationship between these two factors.
However, the results showed that the application of mulch can increase berry potassium and
pH, but the changes are small compared with variations observed among vineyard sites and
between seasons.
The long term impacts on the soil caused by the application of grape marc should be monitored
using soil analysis.
The best results from using grape marc in the vineyard can be gained from fully composted
grape marc.
The storage of grape marc for long periods may be associated with fungal and odor problems
and have the potential to contribute to groundwater pollution.
Composted grape marc producers a finely textured, uniform compost that is rapidly incorporated
into the soil at low application rates.
Ensure that stock piles of grape marc are located away from residences and that runoff
is contained.
Consult your local government association for regulations concerning the storage of
grape marc.
Additional resources to assist your decision making can be accessed at the following websites.