Soil structure is vitally important for plant-soil and plant-water relations. It is also extremely vulnerable to damage by ploughing or tilling. Disturbed soils rapidly revert to bacterially dominated status and in this state quickly become dominated by first succession weeds (thistle, fat-hen, mallow etc) and grasses. Soils that are left undisturbed and which are allowed to accumulate biomass through the activity of natural composting and earthworms slowly become fungally dominant, much like the soils of a forest floor ,,, the original home of wild vines.
This philosophy is in direct contrast to Biodynamics which requires regular ploughing.
We believe that to produce high quality Pinot Noir requires optimum soil tilth and fertility in the vineyard. These are directly related to biological soil structure or the soil-food-web.
Soil crumb structure is built from the bottom up, through microbial bio-agglutination of the smallest soil particles, which then aggregate into larger, electrically neutral, crumbs. The pores formed between these crumbs act as capillaries that facilitate water and air movement and protect against evaporation.
In this special soil micro-climate, vine roots interact with the soil food web (bacteria, fungi, nematodes and earthworms). Bacteria dominate the top soil layer (3-8cm). The layer we are more interested in, lies beneath the top-soil layer and is called the plasma-tilth horizon. When soils are left undisturbed, this layer can grow 1-2m deep. Yes, "grow": this is a living soil layer! And this is the depth we expect our vines roots to actively explore.
This layer is dominated by fungi that produce a bio-agglutinating glycoprotein called glomulin. The nice thing about glomulin is that it sequesters large amounts of carbon. It also binds to silt, sand and clay particles forming stable soil crumbs. Vines, as they grow, secrete large amounts of root exudates from their root tips (as much by weight as there is plant matter above ground). Aerobic micorrhizal fungi feed on these root exudates in a symbiotic relationship with the vine, helping the vine roots to explore deeper and deeper. As the depth of the plasma-tilth horizon extends, the vine becomes naturally more resilient to drought and reduce reliance on irrigation.
Mechanically crumbled or ploughed soils lose these qualities, start silting and growing weeds like thistles, nettles, fat hen and annual grasses. If left undisturbed, over time, as these plants die and enrich the soil, they would be replaced by perennial grasses and other plants, then woody shrubs. In many areas, these would eventually be overgrown by native trees and become a forest. Plant ecologists call this natural pattern ‘vegetation succession’. If the soil is continually disturbed by ploughing or tilling, the early succession "weeds" would continue to appear. Bearing in mind the weed seed potential of most soils is about 20,000 seeds/m2, this is a battle you just can't win without heavy duty herbicides which themselves decimate soil biology, leaving it barren, compacted or collapsed, and lifeless.
The natural habitat of vines is forests with deep rich soils dominated by fungi. So this is the environment we are trying to give them here at Fancrest Estate.
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