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Place · November 21, 2025 · 4 min read

Terroir Part 2: The Nutrients

Here we have the next part in our soil evaluation series and another picture of me in the Mosel River Valley on the steepest site I have ever seen. It was VERY cool swerving through the little one-lane roads through villages up to kinda frightening vineyards. I highly recommend a pilgrimage to this remote, off the beaten European trail, Germany's Mosel River embodies it. Its terroir is uniquely viewable with paths like the one in Calmont shown above where you can see the blue slate piled up with no soil above it and get queasy looking down the harvesting Monorackbahn wondering how these people harvest a whole site like this safely. Did I mention the wine is sublime here too whether you like that sweet, sweet acidity, bone-dry crisp, or the Grand Cru Auslese in the middle.

Anyway, these posts are all trending toward learning and comparing the terroirs of some of the famous sites around the world and especially to the locale where I am working toward planting a vineyard. Understanding your soil and choosing the correct site is the best way to get the type of start we need to be successful. Most of these numbers below and on the previous pages come from research of locations and working with AI in building the knowledge enough to build these blog posts. You will see at the bottom of this one that I list some of the world's most famous wine-growing areas and their CEC percentages. I will also include my location that I would like to begin making wine on too. I would love to hear your questions and comments.

CEC Calcium (Ca)

  • Why it matters: Cell-wall strength, berry firmness, and disease resistance; improves soil structure (flocculation) and root exploration; tempers K uptake and buffers soil pH without spiking must pH.
  • Balance point: Aim for Ca to dominate exchange sites without smothering Mg/K. Target ~65–75% base saturation Ca, Ca:Mg ~3–8:1, Ca:K ~10–20:1 (CEC basis). If Ca is already high, use gypsum (adds Ca, no Mg) rather than dolomite.

CEC Magnesium (Mg)

  • Why it matters: Chlorophyll, enzyme cofactor. Too little → interveinal chlorosis; too much → tight soils and K antagonism.
  • Balance point: Keep Mg in the benchmark range and manage through dolomite avoidance if Ca is already high.

CEC Phosphorus (P)

  • Why it matters: Energy/ATP transfer, early root growth, flowering/fruit set, winter hardiness; availability drops in high-Ca (calcareous) or very high pH soils.
  • Balance point: Keep modest and plant-available, avoid big builds. For calcareous soils, Olsen P ~10–20 ppm (sweet spot ≈ 15 ppm). Band or fertigate small doses; over-application ties up fast and can unbalance vigor.

Potassium (K)

  • Why it matters: Osmoregulation, sugar transport, stomatal control. But excess K elevates must pH (tartrate precipitation) and antagonizes Mg/Ca, especially problematic for crisp, tension-driven sparkling bases.
  • Balance point: Keep K adequate, not high. Target ~2–5% base saturation K (often 3–4% ideal) and roughly 100–150 ppm (common Mehlich-3 guidance) on limestone sites geared for méthode traditionnelle. Use cover crops and gypsum to moderate luxury uptake; avoid broad potash applications unless leaf/petiole data prove need.

CEC Sodium (Na)

  • Why it matters: Small amounts are physiologically tolerated, but Na mainly harms soil structure (dispersion), raises sodicity/salinity risk, and competes with K/Ca/Mg.
  • Balance point: Keep Na base saturation <1–2%, ESP <6%, SAR <3, soil EC <1 dS/m for non-saline conditions. If elevated, improve drainage, add Ca (gypsum) where appropriate, and manage irrigation water quality.

Micronutrients (Fe, Zn, Mn) & Sulfur (S)

  • Fe: Low on chalk isn't shocking; foliar chelates if vine tissue shows deficiency.

Key for chlorophyll synthesis and electron transport, so it directly controls how hard the vine's "solar panels" can run. On high-pH, calcareous soils, Fe lockout shows up as bright interveinal chlorosis on young leaves, weak canopies, and poor ripening even when total Fe is high.

  • Zn: Your limiting factor for fruit set; schedule foliar Zn at pre-bloom.

Critical for auxin (growth hormone) and enzyme systems that regulate shoot growth, bud fertility, and flower/fruit set. Low Zn means tiny, cupped leaves, short internodes, "rosetted" shoot tips, and poor fruit set/shatter, so your yield and cluster architecture quietly fall apart.

  • Mn: In-range; biology will regulate.

Central to photosynthesis (Photosystem II) and several oxidative enzymes, helping with sugar production, lignification, and stress defense. Deficiency on high-pH sites gives subtle mottled chlorosis on older leaves; excess on low-pH soils can cause speckling and toxicity that drags down canopy performance.

  • S: Under-supplied in our soils; elemental S boosts microbial metabolism and modestly acidifies over time.

Building block for sulfur-containing amino acids and glutathione, so it sits at the crossroads of protein synthesis, yeast nutrition, and oxidative stability in juice and wine. In the vineyard it's also your backbone fungicide. True S deficiency is rare but shows up as a pale, N-deficiency-lookalike canopy with muted growth and lower YAN at harvest.

Next stop in the series, we will do some benchmarking!