Sustainability at Chateau Tanunda 3: Soil Health

Tuesday, 16 November 2021

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The Barossa has some natural gifts when it comes to our rainfall patterns. Late Winter and Spring are the wettest times of the year and natural rainfall levels mean we have limited water requirements from irrigation. The deep soils on the valley floor also have reasonable water holding capacity which sustains healthy vine growth. However the climate is trending to decreased rainfall and hotter dryer summers so we are changing our vineyard practices to suit.

We are maximising our water use efficiency through two key areas: Increasing Soil Carbon levels and Soil microbiology, our biggest innovation area.

Soil Carbon

The moisture holding capacity of soils with high organic carbon levels is greatly increased. However Increasing carbon levels in soil is difficult, slow and time consuming. We are undertaking two main areas to improve soil carbon levels.

  • Planting an adventurous mix of winter cereal and legume cover crops that have vigorous foliage growth during winter. The inter row crop naturally matures and dries in the warmer months thereby not competing for moisture. Then the cover crop is left in the vineyard to add to soil organics. We do not disturb the soil, leaving plants to breakdown above and below the surface,  decreasing moisture loss during summer and increasing organic matter below the surface (which eventually become carbon).
  • Adding increased levels of high quality composted organic matter. We are using and recycling our grape waste into a high organic matter, high carbon compost. This is being incorporated into the vineyard at every opportunity and we are seeing vine health respond dramatically.

Soil Microbiology

The ability of a vine to explore a greater volume of soil and therefore nutrients and moisture is greater in soils with a healthy soil micro-biome. It is about building soils filled with healthy microbes. Microbe populations recover quickly when practices that limit their growth are stopped.

We are focusing on new dryland farming techniques that encourage soil microbial populations. Such as:

  • Reducing soil compaction through use of different machinery that helps to keep oxygen levels in the soils up. We have a small tyne that follows the tractor wheel, undoing any compaction that may occur.
  • Minimal or nil soil surface disturbance.
  • Mixed nitrogenous cover crops (legumes)
  • Ceasing all salt based fertilizer use.
  • Using undervine weed mats, composts etc. to reduce and eventually remove all herbicide use.

These two areas are already showing us that they work very effectively and that much less supplemental water by irrigation is required. These are the new dryland farming techniques!