By Charles Williams (Winemaker)
As winegrowers we are very dependent on nature for our livelihood. The observation and study of nature never fails to amaze, breeding a thorough respect and love for these biological systems.
As custodians of the ground, we need to apply integrated, biological systems to keep our soils alive and nourished, to in turn supply our vines with all the elements it needs to grow grapes of superior quality. We do this in a few ways: producing and introducing compost into our vineyards, applying Mycorrhizae to the soils (these are fungi that colonizes the root of plants and create symbiotic relationships in managing plant water and nutrient absorption) and planting specific cover crops between our vineyard rows to fulfil specific rolls.
Cover crops (commonly used species including Wheat, Lupines and White Mustard) have multiple advantages. To optimize these advantages, precision farming is of the utmost importance, and as we at De Toren do not believe in taking a blanket approach on ANYTHING this plays well into our hand!
During autumn we will collect soil samples from every differential area in our vineyards. These analysis will show the balance of nutrients in the soil, what elements are either abundant or scares and how much of each is easily available to the vines. By using the soil data in conjunction with our knowledge of the cultivar planted to that specific soil we will match up specific cover crops to that combination.
This year we have opted for 3 different cover crops:
– Bitter Lupins
– Vicia sativa
Wheat has the ability to produce a big amount of biomass. This is good to increase the organic material in the soils. This cover crop is great for healthy, balanced soils. Apart from the advantages of imparting good amount of organic material into the soil, it also has a fibrous root system (see picture) that occupies the topsoil and suppress the germination and growth of winter and annual weeds.
Bitter Lupins is a Legumes specie that have the ability to fixate nitrogen, once it dies, it releases and replenish the soil nitrogen. This makes it perfect for marginal soil with a high rock content. Because it has a very strong taproot system it also makes it a viable option for soil with a high clay content. The roots grow deep into the soil and once the plant dies the roots decompose leaving small “tunnels” in the soil for water and organic material to be carried deep into the soil.
Vicia sativa is also a Legumes plant. It has a very strong implantation rate and will grow a good amount of biomass. It is a very strong nitrogen fixating plant. Perfect for sandy soils and to help stimulate growth for cultivars like Petit Verdot.
These cover crops are key to our continued approach towards successfully applying biological and sustainable farming techniques and in yearly rotation can be very successfully utilized towards achieving and maintaining good, healthy soils!