ENRU

    Arrows to move, Enter to open

    Clay

    The finest particles in the soil, which hold more water than sand.

    Clay in the atlas

    1. Atlas regionRioja
    2. Atlas regionBordeaux
    3. Atlas regionChianti Classico
    4. Atlas regionTokaj
    5. Atlas regionKakheti
    6. Atlas regionBarossa Valley

    Atlas regions where this rock appears in the text or the soil profile.

    Pick a place and the globe turns to it. You can also drag the globe.

    What it is

    Clay is the finest particle-size class in a soil: particles smaller than 0.002 mm.1

    clay
    gravel
    limestone

    Schematic: how fast water drains through the rock. A qualitative comparison based on the sources on this page.

    Water

    Texture largely decides how much water a soil can hold: about 5% available water in a very sandy soil against about 10% in a very clayey one.2 Vine water status in turn shapes the grapes: a moderate deficit raises anthocyanins in the skins, while a severe one can harm red wine quality.2

    In Saint-Émilion, Merlot is noted as particularly suited to cool, damp clay soils.3

    Where to see it

    Clay-limestone soils cover 95% of Rioja Alavesa in Rioja.4 In Kakheti, the Tsinandali vineyards grow on very thick heavy-clay soils.5

    Regions

    Sources

    1. Soil classification systems (Forage Information System). Oregon State University. level 4 · checked 2026-10-13
    2. Soil-related terroir factors: a review (van Leeuwen, Roby, de Rességuier, OENO One 52(2):173-188). OENO One, 2018. level 3 · checked 2026-10-13
    3. Saint-Emilion Grand Cru PDO technical file (PDO-FR-A0993). European Commission eAmbrosia / Conseil des Vins de Saint-Emilion. level 1 · checked 2026-10-13
    4. Rioja Alavesa. Consejo Regulador DOCa Rioja. level 1 · checked 2026-10-13
    5. Tsinandali wine — PDO product specification (applicant: LEPL National Wine Agency of Georgia). UK GOV (GI register publication) / National Wine Agency of Georgia, 2023. level 1 · checked 2026-10-13