“I’m always surprised by those who see Mars as our next frontier for exploration. What about the ground beneath our feet? We’re just beginning to learn how rich and diverse it is. It’s literally crammed with information on which our survival as a planet depends. Shouldn’t that be the quest we make our priority?” asks agricultural specialist for Distell, Henk van Graan.
His focus is on holistic, low-intervention farming in the pursuit of creating a more resilient terroir for Nederburg, where ultimately healthier vines will lead to even better wines and inputs such as chemical fertilizers, pesticides and herbicides can be curtailed, if not altogether eliminated.
“When I studied viticulture in the 1990s, soil wasn’t given that much emphasis. In those days, it was considered more of a planting medium to be treated with appropriate interventions for optimal vine growth. It’s only in recent years that awareness about intrinsic soil life and health has grown, and with it an awareness of the connection to climate resilience and food security.
“As we move towards more regenerative farming, where we start with the health of the soil, we are beginning to uncover the extent to which beneficial micro-organisms of the soil food web (bacteria, fungi, protozoa etc.) are linked to sustainability. Ironically, while this type of farming involves many ancient practices, in some ways it represents a whole new frontier for modern farmers. Especially as we deepen our knowledge of mycorrhizal networks, where microorganisms in the root systems of plants connect individual plants together and transfer water, carbon, nitrogen, and other nutrients and minerals.
“We’ve come to understand that around 70% of the earth’s microorganisms exist below the surface of the ground. That’s more diversity below than above ground. To consider this on a micro-scale, can you imagine that there can be more than 25 000 species of microorganisms in a single teaspoon of soil!
Microbes matter
“As we begin to appreciate the ecosystems of healthy soils, we are learning in more detail about how their microbial populations provide structural support for all types of plants. They help to fix nitrogen, aerate, moisturise and enrich the soil. Carbon compounds are released by plant roots into the soil to feed billions of organisms and cycle nutrients. As a result, aggregate habitat is created to play an important role in filtering, retaining, and draining water.”
Microbial communities also play an important role in carbon sequestration, using light energy converted into chemical energy (carbon compounds via root exudates) that is stored in the soil during photosynthesis.
Van Graan quotes soil scientist and conservation agronomist Ray Archuleta to explain: “The plant and soil are one”. In other words, without plants, we wouldn’t have microbes and without microbes, we couldn’t call it soil.
In South Africa, where the threat of drought is never far away, cover cropping in vineyards has long been an important way of promoting soil health and biodiversity, while reducing evaporation and regulating temperatures. The roots of cover crops feed and stimulate the populations of soil microorganisms that recycle plant material and enrich the soil with nutrients. In time, these nutrients will feed future cover crops and, of course, the vines themselves.
Under Van Graan, cover crops planted at Nederburg have included oats, lupins, fava beans and vetch. He is finding that healthier soils, leading to more abundant cover crops, bring more beneficial insects that act as natural insecticides and pesticides.
