Cover Crop

Why do we sow a cover crop between the vines?

We select cover crops that require the same soil biology as grapevines which means that symbiotic fungi such as mycorrhiza can attach to both the vine roots and the cover crop roots to trade nutrients if required.
 
The winter cover crops grow when the vine is dormant and utilises nutrients and moisture in the soil that would have otherwise been leached due to winter rains. These cover crops which are grown in the rows between the vine out-compete and often shade out undesired weeds. Some grain crops also have allelopathic effects on specific weeds and we are currently including barley with oats and rye to help suppress the growth of wireweed.
 
By incorporating other desired crops into the vineyard we are also moving away from a monoculture system that lacks diversity. The encouragement of useful plants into our vineyard system helps to provide alternative sources of food and habitat for the beneficial insects and soil biology, which means that the vineyard is better placed to deal with outbreaks of pests and diseases.

By direct drilling the winter crop and scatter seeding the summer crop, we are able to improve the soil structure because we are not cultivating the soil. The soils capacity to become less compacted is due to the root growth of the cover crop creating pores and channels for air and water to infiltrate rapidly. Cover crops also produce large quantities of organic matter that we currently use for mulching under the vines and this provides a perfect food source for micro-organisms. Longer term, we feel that we will harvest the inter-rows for inclusion in our composting activities.
 
We have developed our own 'crop roller' attachment for the tractors to assist in mulching. The roller crushes the stalks of the current crop while they are still green causing the vascular system to stop functioning. This effectively traps the nutrients in the aerial parts of the plants for the consumption by organisms such as earthworms. To reduce compaction further we have designated 'non-travel' rows whereby no vehicle will pass down that particular row for a set period of time. However to manage the cover crop this is one of the few times the tractors use the 'non-travel' rows. To decrease the trips down these rows this operation effectively covers 3 separate tasks in the one pass:

• crimping the oat crop

• sowing the summer millet crop underneath the rolled oats

• Aerating the soil (and down the track we plan to add a compost tea sprayer onto the aerator)

The plan is to crimp the oats and grow millet under the new oat mulch, once the millet is established we can then mow, side-throwing the oat crop and young millet shoots to provide much needed organic mulch undervine. This all happens at a time when the soils are starting to dry out so this in turn reduces the water loss from underneath the vine and alleviates the need for herbicide use to control undervine weeds.