Many Australian grape growers are evaluating the use of traditional under-vine soil management
techniques in order to improve soil conditions and vineyard performance.
Traditionally, most Australian vineyards are managed to maintain a bare under-vine strip.
There are many advantages to using a system like this.
The major benefit of maintaining a weed free under-vine area is that there is no competition
with the vines for water and nutrition.
Bare soil under-vine also provides a high level of solar reflection and heat.
In some situations, this may protect vines against spring frost.
A clear herbicided under-vine strip is relatively easy to manage and cost effective to maintain.
A bare soil under-vine also comes with disadvantages.
Long term reliance on synthetic herbicides can lead to herbicide resistance in weeds.
It is important to follow a herbicide resistance management strategy to avoid this occurring.
Plant roots provide many important functions in soil.
Plant roots provide an important food source for soil organisms including bacteria, fungi,
protozoa, insects and earthworms.
Without plant roots, soils are limited in the diversity of soil biology they can support
and this reduces the potential for the natural cycling of nutrients in the soil.
Without plants and with limited soil biological activity, some soils are prone to surface
water pooling especially under drip irrigation.
These soils tend to have poor water infiltration and uneven distribution of soil moisture through
the soil profile.
The higher solar radiation and reflection caused by bare under-vine soils can significantly
increase the vine canopy temperature.
At very high temperature this can be detrimental to the fruit and vines.
Two alternatives to bare under-vine soils include: allowing plants to grow under the
vines and the use of compost and mulch.
Plant roots can penetrate compact soils and provide a pathway for water to infiltrate.
Improved soil structure, moisture and the addition of a food source make soils more
conductive to soil biological activity.
However, under-vine plants compete with the vines for soil moisture and nutrients.
If the completion is great, vines may have decreased shoot growth and yield.
This is exacerbated when water supplies are limited.
This figure shows the drying pattern of an under-vine soil with weeds growing in it (the
red line) and a neighboring soil without weeds (the blue line).
It is clear that the soil with the weeds growing in it is drier than the weed-free soil.
In this vineyard, despite early season increases in soil biological activity which was beneficial
in the vineyard, the vines growing with under-vine weeds for four years has a 30% decrease in
yield with no improvement in fruit or wine composition.
In some cases where vine growth is excessively vigorous or yield is very high, reductions
in canopy growth and yield may have a positive effect on overall vine balance and improved
fruit and wine composition.
Changes to under-vine soil management requires evaluation of the risks and benefits to soil
condition and vine performance.
Additional resources to assist your decision making can be accessed at the following websites