Tillage exposes the soil to the air so that it breaks down and enables CO2 to be released back into the atmosphere. Deeper tillage leads to more carbon lost to the atmosphere. It also damages the microbes in the soil and breaks up the mycorrhizal relationships between the plant roots and the beneficial fungi in the soil. This reduces the vines’ potential to access nutrients in the soil.
Minimizing tillage is fundamental to maximizing soil carbon stocks, reducing soil compaction, preserving the microbiome in the soil, increasing water and nutrient retention, and facilitating the establishment of a rich biodiverse ground cover and the subsequent ecological benefits that bring.
If you ever invert the soil in the inter row, as a method of weed control, or to aerate the soil, you are likely to be damaging your soil biology and reducing your soil organic matter.
Occasionally cultivating the top few centimeters of topsoil to help establish cover crops may be beneficial, especially to get a healthy system up and running. Once the desired sward is established, it should be possible to manage it with mowing and mulching.
Tilled soil has:
- Less carbon sequestered
- Less water holding capacity, which means there is less available water for the vines and also increased risk of soil erosion and nutrient run off
- Reduced ability to deliver nutrients to the vine’s roots in plant available form
- Reduced ability to fight off pathogens
- Soil that is unsuitable for passage of machinery when it has been raining
- Higher temperatures as the soil is exposed to the sun, with very high temperatures causing further damage to soil life
- Increased evaporation resulting in even lower water availability
The rationale for bare earth in vineyards has now been discredited in most vineyard contexts. Therefore, tillage in the interrow is not considered as necessary, and is not as common, as it once was.
Vineyard ground cover in the interrow area is increasingly common, either in the form of native species such as grasses, clovers and wildflowers, which are allowed to regenerate naturally, or the sowing of specific cover crops, ideally direct drilled into the existing ground cover. Once established, there should be less need for tillage of the interrow areas.
Concerns regarding competition for nutrients and water in drought conditions are being balanced by findings that ground cover both reduces soil temperatures and evaporation and that the roots improve the soil structure so that the soil has a higher water holding capacity. They also reduce soil erosion and nutrient run off in high rainfall events.
Management of the interrow is often done by mowing or crimping and rolling. Both can be done on an alternate row basis to provide continual habitat for pollinators and invertebrates.
Increasingly, grazing animals are being incorporated into the vineyard to control ground cover growth. This brings the added benefit of fertiliser addition.
Further information on cover crops in the Cover Crops section